Fasting is No Better For You Than Regular Calorie Restriction - new Scientific Study - POSTED ON: May 03, 2017
A Scientific Study was recently published concluding that an alternate-day fasting diet was NOT superior to a daily calorie restriction diet for Metabolically Healthy Obese Adults with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease (including insulin resistance).
The lead researcher in this study, Dr. Krista Varady, has previously done extensive research on Alternate Day Fasting. Those studies are currently considered the best scientific authority on Intermittent Fasting, and her previous research findings have often been extensively quoted by the majority of Intermittent Fasting Gurus, including Dr. Jason Fung, author of The Obesity Code (2016) and The Complete Guide to Fasting (2016)
Below is a recent article from TIME.
Fasting Isn’t Better for You Than Regular Dieting
Alexandra Sifferlin May 01, 2017 TIME
Losing weight is hard, which is why weight loss experts have long searched for different approaches to make it easier for people. One strategy gaining steam is intermittent fasting, where people fast or lower their calories substantially for a short period of time. (This diet plan also has potential lifespan-extending benefits.)
But new research published in JAMA Internal Medicine suggests that the fasting diet may not be the weight loss key it's been hyped up to be.
In the new trial, researchers wanted to know whether people who tried a fasting diet would be more successful than those on a standard diet. They told 100 people with obesity to follow one of three diets for a year. Some were told to cut their calorie consumption by 25% per day—a typical calorie restriction diet—while others did an alternate-day fasting diet, where they ate about 500 calories on “fast” days and whatever they wanted on “feast" days. The last group, which served as the control group, ate what they normally would.
The researchers expected that the people in the fasting group would lose more weight and have an easier time sticking to the diet than regular dieters, but the results didn't reflect that. At the end of the year, people who did the fasting diet and those who just cut calories both lost an average of 13 pounds. However, people in the fasting group actually had a harder time sticking to the diet, and more people in that group dropped out of the study.
“I really thought people would have an easier time and lose more weight on the [fasting diet] and I was shocked they lost the same amount,” says study author Dr. Krista Varady, an associate professor of nutrition the University of Illinois at Chicago and author of the book The Every-Other-Day Diet. “The take-home message for me is that this diet isn’t for everyone.”
The researchers also did not find significant differences in other health measures between the dieting groups, like blood pressure, heart rate or insulin resistance.
Dr. Varady says that while half of the people in the fasting group "could barely do the diet," there were several people who were very successful, losing between 20 to 50 pounds. Those findings suggest that some people do respond well to the diet.
Still, what works for one person clearly doesn’t work for everyone. “If people have failed other diets, maybe this will work,” Dr. Varady says. “People will pick what diet works best for them."
Below are Excepts from a recent CNN article about this scientific research study.
The study suggests that there is no significant difference between fasting and the other popular weight loss strategy of simply restricting how many daily calories you consume.
Dr. Varady said that, before the study, she thought alternate-day fasting would be an easier diet to adhere to because it allowed for a "break" from dieting every day.
"We were a little bit shocked to see that it was actually the calorie-restriction group that seemed like they could stick better to their daily calorie goals. Whereas the alternate-day fasting group, they were kind of wavering," said Dr. Varady, who authored a book about alternate-day fasting called "The Every-Other-Day Diet."
"Instead of eating the 500 calories on the fasting days, they were eating a couple hundred calories more on those days," she said.
'Not one diet fits everyone'
All in all, the new study showed that alternate-day fasting may be difficult to follow but can be effective in reducing obesity, said Valter Longo, a professor at the University of Southern California and director of the university's Longevity Institute. He was not involved in the study.
However, "because it requires a major effort every other day, it is unlikely to be applicable to the great majority of the obese population, particularly in the absence of the close monitoring carried out in the clinical study," Longo said.
For overweight or obese adults who might be interested in alternate-day fasting as a weight loss approach, Dr. Varady advised taking the time to really determine whether it is the best option. "I really think people just need to find what works for them," she said. "Not one diet fits everyone."
"I don't think there's anything magical to the diet at all," she said of alternate-day fasting. "I think it's just another way of tricking people into eating less food or helping people to kind of monitor how much food intake there is or how much food they're taking in."
Below is a copy of the published research study.
This study can also be found at:
May 1, 2017
Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults
A Randomized Clinical Trial
John F. Trepanowski, PhD1; Cynthia M. Kroeger, PhD1,2; Adrienne Barnosky, MD1; et al Monica C. Klempel, PhD1; Surabhi Bhutani, PhD1; Kristin K. Hoddy, PhD, RD1; Kelsey Gabel, MS, RD1; Sally Freels, PhD3; Joseph Rigdon, PhD4; Jennifer Rood, PhD5; Eric Ravussin, PhD5; Krista A. Varady, PhD1
Author Affiliations Article Information
JAMA Intern Med. Published online May 1, 2017. doi:10.1001/jamainternmed.2017.0936
Question Is alternate-day fasting more effective for weight loss and weight maintenance compared with daily calorie restriction?
Findings This randomized clinical trial included 100 metabolically healthy obese adults. Weight loss after 1 year in the alternate-day fasting group (6.0%) was not significantly different from that of the daily calorie restriction group (5.3%), relative to the no-intervention control group.
Meaning Alternate-day fasting does not produce superior weight loss or weight maintenance compared with daily calorie restriction.
Importance Alternate-day fasting has become increasingly popular, yet, to date, no long-term randomized clinical trials have evaluated its efficacy.
Objective To compare the effects of alternate-day fasting vs daily calorie restriction on weight loss, weight maintenance, and risk indicators for cardiovascular disease.
Design, Setting, and Participants A single-center randomized clinical trial of obese adults (18 to 64 years of age; mean body mass index, 34) was conducted between October 1, 2011, and January 15, 2015, at an academic institution in Chicago, Illinois.
Interventions Participants were randomized to 1 of 3 groups for 1 year: alternate-day fasting (25% of energy needs on fast days; 125% of energy needs on alternating “feast days”), calorie restriction (75% of energy needs every day), or a no-intervention control. The trial involved a 6-month weight-loss phase followed by a 6-month weight-maintenance phase.
Main Outcomes and Measures The primary outcome was change in body weight. Secondary outcomes were adherence to the dietary intervention and risk indicators for cardiovascular disease.
Results Among the 100 participants (86 women and 14 men; mean [SD] age, 44  years), the dropout rate was highest in the alternate-day fasting group (13 of 34 [38%]), vs the daily calorie restriction group (10 of 35 [29%]) and control group (8 of 31 [26%]). Mean weight loss was similar for participants in the alternate-day fasting group and those in the daily calorie restriction group at month 6 (–6.8% [95% CI, –9.1% to –4.5%] vs –6.8% [95% CI, –9.1% to –4.6%]) and month 12 (–6.0% [95% CI, –8.5% to –3.6%] vs –5.3% [95% CI, –7.6% to –3.0%]) relative to those in the control group. Participants in the alternate-day fasting group ate more than prescribed on fast days, and less than prescribed on feast days, while those in the daily calorie restriction group generally met their prescribed energy goals. There were no significant differences between the intervention groups in blood pressure, heart rate, triglycerides, fasting glucose, fasting insulin, insulin resistance, C-reactive protein, or homocysteine concentrations at month 6 or 12. Mean high-density lipoprotein cholesterol levels at month 6 significantly increased among the participants in the alternate-day fasting group (6.2 mg/dL [95% CI, 0.1-12.4 mg/dL]), but not at month 12 (1.0 mg/dL [95% CI, –5.9 to 7.8 mg/dL]), relative to those in the daily calorie restriction group. Mean low-density lipoprotein cholesterol levels were significantly elevated by month 12 among the participants in the alternate-day fasting group (11.5 mg/dL [95% CI, 1.9-21.1 mg/dL]) compared with those in the daily calorie restriction group.
Conclusions and Relevance Alternate-day fasting did not produce superior adherence, weight loss, weight maintenance, or cardioprotection vs daily calorie restriction.
Trial Registration clinicaltrials.gov Identifier: NCT00960505
The first-line therapy prescribed to obese patients for weight loss is daily calorie restriction.1 However, many patients find it difficult to adhere to a conventional weight-loss diet because food intake must be limited every day.2 As such, adherence to daily calorie restriction decreases after 1 month and continues to decline thereafter.3- 5 In light of this limitation, another approach that requires individuals to restrict calories only every other day was developed.6 This strategy is called alternate-day fasting and involves a fast day where individuals consume 25% of their usual intake (approximately 500 kcal), alternated with a “feast day” where individuals are permitted to consume food ad libitum. Findings from short-term studies indicate that participants lose 3% to 7% of body weight after 2 to 3 months of alternate-day fasting and experience improvements in lipid profiles, blood pressure, and insulin sensitivity.7- 13
Alternate-day fasting regimens have increased in popularity during the past decade, and several best-selling diet books14,15 have promoted this approach. More than 1 million copies of these books have been sold in the United States and United Kingdom to date. Despite the growing popularity of alternate-day fasting, to our knowledge, no long-term randomized clinical trials have evaluated its efficacy or compared this regimen with a conventional weight-loss diet.
We conducted a 1-year, randomized clinical trial to compare the effects of alternate-day fasting vs daily calorie restriction on body weight and risk indicators for cardiovascular disease. We hypothesized that the participants in the alternate-day fasting group would be more adherent to their diet, achieve greater weight loss, and experience more pronounced improvements in risk indicators for cardiovascular disease during the 6-month weight-loss phase compared with those in the daily calorie restriction group. We also hypothesized that the alternate-day fasting group would better maintain their weight loss and sustain their improvements in risk indicators for cardiovascular disease during the 6-month weight-maintenance phase compared with the daily calorie restriction group.
We conducted the trial between October 1, 2011, and January 15, 2015, at the University of Illinois at Chicago. Participants were recruited from the Chicago area by means of flyers placed around the university and were screened via a questionnaire, an assessment of body mass index, and a pregnancy test. Individuals included were men and women between 18 and 65 years of age, with a body mass index between 25.0 and 39.9 (calculated as weight in kilograms divided by height in meters squared) who had previously been sedentary (<60 minutes per week of light activity for the 3 months prior to the study).
Exclusion criteria were a history of cardiovascular disease or type 1 or 2 diabetes, use of medications that could affect study outcomes, unstable weight for 3 months prior to the beginning of the study (>4-kg weight loss or gain), perimenopause or otherwise irregular menstrual cycle, pregnancy, and currently smoking. The protocol was approved by the Office for the Protection of Research Subjects at the University of Illinois at Chicago, and written informed consent was obtained from all participants. The full protocol is available in Supplement 1.
Randomization and Intervention Groups
Participants were randomized in a 1:1:1 ratio to an alternate-day fasting group, daily calorie restriction group, or no-intervention control group. Randomization was performed by a stratified random sampling procedure by sex, age (18-42 years and 43-65 years), and body mass index (25.0-32.5 and 32.6-39.9). Block size ranged from 1 to 11 participants. The active trial duration was 1 year and consisted of a baseline phase (1 month), a weight-loss phase (6 months), and a weight-maintenance phase (6 months) (eFigure 1 in Supplement 2). We chose this design because weight loss typically peaks at 6 months during a lifestyle intervention.16 During the baseline phase, all participants ate their usual diet and maintained a stable weight. Baseline total energy expenditure was measured using doubly labeled water.17 All participants were instructed not to change their physical activity habits throughout the trial (eg, not to join a gym) to avoid potential confounding.
Participants in the alternate-day fasting group and those in the daily calorie restriction group were provided with all meals during the first 3 months of the trial and received dietary counseling thereafter (eFigure 1 in Supplement 2). During the 6-month weight-loss phase, the intervention groups were instructed to reduce their energy intake by a mean of 25% per day. To achieve this reduction, the alternate-day fasting group was instructed to consume 25% of baseline energy intake as a lunch (between 12 pm and 2 pm) on fast days and 125% of baseline energy intake split between 3 meals on alternating feast days. The daily calorie restriction group was instructed to consume 75% of baseline energy intake split between 3 meals every day. The provided meals were in accordance with the American Heart Association guidelines18 for macronutrient intake, with 30% of energy as fat, 55% as carbohydrate, and 15% as protein. From months 4 to 6, when food was no longer provided, intervention participants met individually with a dietician or nutritionist weekly to learn how to continue with their diets on their own.
At the beginning of the 6-month weight-maintenance phase, total daily energy expenditure was reassessed using doubly labeled water.17 Participants were instructed to maintain their body weight during this phase. Participants in the alternate-day fasting group were instructed to consume 50% of energy needs as a lunch on fast days and 150% of energy needs split between 3 meals on alternating feast days. Participants in the daily calorie restriction group were instructed to consume 100% of energy needs split between 3 meals every day. Intervention participants met with the dietician individually each month to learn cognitive behavioral strategies to prevent weight regain19 and received personalized energy targets for weight maintenance based on results from doubly labeled water.
Control Group Protocol
Participants in the control group were instructed to maintain their weight throughout the trial and not to change their eating or physical activity habits. Controls received no food or dietary counseling but visited the research center at the same frequency as the intervention participants (to provide outcome measurements). Controls who completed the 12-month trial received 3 months of free weight-loss counseling and a 12-month gym membership at the end of the study.
The primary outcome of the study was change in body weight, which was measured monthly via a digital scale while the participant was in a hospital gown. Fat mass and lean mass were measured every 6 months in the fasted state by dual-energy x-ray absorptiometry (QDR 4500W; Hologic). Visceral fat mass was measured every 6 months by magnetic resonance imaging performed with a 1.5-T magnet (Siemens Vision), and images were analyzed using validated software.20
Mean percentage energy restriction during the weight-loss phase was retrospectively calculated by the intake balance method using doubly labeled water and changes in body composition.21 Physical activity was measured for 7 consecutive days every 6 months using an activity monitor (SenseWear Armband Mini; BodyMedia Inc).22 Dietary intake and adherence to diets was assessed every 3 months with a 7-day food record and analyzed using Nutritionist Pro software (Axxya Systems LLC). Intervention participants were considered to be adherent when their actual energy intake, determined via food records, was within 200 kcal of their prescribed daily energy goal.
Blood samples were obtained following a 12-hour fast every 6 months (collected on the morning after a feast day for the alternate-day fasting group). Secondary outcomes included blood pressure, heart rate, and total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, fasting glucose, fasting insulin, C-reactive protein, and homocysteine concentrations (analytical methods are detailed in the full protocol in Supplement 1). The homeostasis model assessment of insulin resistance was calculated as insulin × glucose/405, where the unit of measure for insulin is in micro-international units per milliliter and the unit of measure for glucose is milligrams per deciliter.23
For the sample size calculation, we estimated that alternate-day fasting would reduce body weight by 15% by month 69,11 and that daily calorie restriction would reduce body weight by 10% by month 6.24 We calculated that 26 participants per group would provide 80% power to detect a significant difference of 5% in body weight between the alternate-day fasting group and the daily calorie restriction group at month 6, using a 2-tailed independent-samples t test with α = .05. We anticipated a dropout rate of 12%. Thus, we initially aimed to recruit 90 participants (30 per group), assuming that 78 participants (26 per group) would complete the trial. We later decided to recruit 100 participants to increase our statistical power because our dropout rate was higher than expected.
Data are shown as mean values (with 95% CIs) unless otherwise noted. A 2-tailed P < .05 was considered statistically significant. Tests for normality were included in the model, and all data were found to be normally distributed. We conducted an intention-to-treat analysis, which included data from all 100 participants who underwent randomization. Results are reported by intention-to-treat analysis unless indicated otherwise. A linear mixed model was used to assess time, diet, and time × diet effects for each outcome. This model provides unbiased estimates of time and treatment effects under a missing-at-random assumption. Time was not assumed to be linear in the model. This strategy allowed for estimation of time and diet effects (and their interaction) without imposing a linear time trend. The analyses were performed using SAS, version 9.4 (SAS Institute, Inc), and R software, version 3.2.2 (R Foundation for Statistical Computing).
Participant Characteristics and Attrition
Of the 222 participants who were screened, 100 (45.0%) were randomly assigned to the diet or control groups, and 69 (69.0% of those assigned) completed the study (Figure 1). The dropout rate was highest in the alternate-day fasting group (13 of 34 [38%]), relative to the daily calorie restriction group (10 of 35 [29%]) and control group (8 of 31 [26%]). More participants in the alternate-day fasting group than in the daily calorie restriction group withdrew owing to difficulties adhering with the diet. All baseline characteristics had comparable distributions between the alternate-day fasting group, the daily calorie restriction group, and the control group (Table 1). The participants were primarily metabolically healthy obese women.
Prescribed vs Actual Energy Intake Determined via Food Records
On the fast day (Figure 2A), participants in the alternate-day fasting group exceeded their prescribed energy goal at months 3 and 6. On the feast day (Figure 2B), participants in the alternate-day fasting group ate less than their prescribed goal at months 3, 6, 9, and 12. Participants in the daily calorie restriction group (Figure 2C) met their prescribed energy goals at months 3, 6, and 12 but ate less than their prescribed goal at month 9. A higher proportion of participants in the daily calorie restriction group were adherent to their energy goals at months 3, 6, 9, and 12 relative to those in the alternate-day fasting group.
Percentage Energy Restriction Determined via Doubly Labeled Water
From baseline to month 6, the alternate-day fasting group achieved a mean (SD) percentage energy restriction of 21% (16%), and the daily calorie restriction group achieved a mean (SD) percentage energy restriction of 24% (16%), with no significant difference between the intervention groups or compared with the control group (eFigure 2 in Supplement 2).
Physical Activity and Dietary Intake
Data on dietary intake are displayed in eTable 1 in Supplement 2. Percentage of energy intake from fat, carbohydrates, and protein did not differ significantly over time in any of the groups. Physical activity, measured as steps per day, did not change during the course of the trial in any group (eTable 2 in Supplement 2). This level of activity is approximately 1000 to 2000 steps per day higher than that of the average overweight or obese adult.25
Weight Loss and Weight Maintenance
Changes in body weight are displayed in Figure 3 and Table 2. Weight loss was not significantly different between the alternate-day fasting group and the daily calorie restriction group at month 6. At the end of the study, total weight loss was –6.0% (95% CI, –8.5% to –3.6%) for the alternate-day fasting group and –5.3% (95% CI, –7.6% to –3.0%) for the daily calorie restriction group, relative to controls, with no significant difference between the intervention groups. Weight regain from months 6 to 12 (–0.8%; 95% CI, –3.2% to 1.7%) was not significantly different between the alternate-day fasting group and the daily calorie restriction group. Moreover, weight regain from months 6 to 12 was not significantly different between the alternate-day fasting group and controls (0.8%; 95% CI, –1.8% to 3.3%), or the daily calorie restriction group and controls (1.5%; 95% CI, –0.8% to 3.9%). Changes in body composition are reported in Table 2. There were no statistically significant differences between the alternate-day fasting group and the daily calorie restriction group for fat mass, lean mass, or visceral fat mass at month 6 or month 12.
Blood Pressure and Heart Rate
Blood pressure was not significantly different between the intervention groups, or relative to controls, at month 6 or month 12 (Table 2). There were also no statistically significant differences in heart rate between the alternate-day fasting group and the daily calorie restriction group at month 6 or month 12 (Table 2).
Changes in plasma lipids during the course of the trial are shown in Table 2. Total cholesterol levels were not significantly different between the intervention groups, or relative to controls, at month 6 or month 12. At month 6, high-density lipoprotein cholesterol levels were significantly elevated in the alternate-day fasting group by 6.2 mg/dL (95% CI, 0.1-12.4 mg/dL) (to convert to millimoles per liter, multiply by 0.0259) vs the daily calorie restriction group, but this effect was no longer observed by month 12. Low-density lipoprotein cholesterol concentrations did not differ significantly between the intervention groups at month 6. At month 12, low-density lipoprotein cholesterol levels significantly increased in the alternate-day fasting group (11.5 mg/dL [95% CI, 1.9-21.1 mg/dL]) (to convert to millimoles per liter, multiply by 0.0259) relative to the daily calorie restriction group. Triglyceride levels did not differ significantly between the intervention groups at month 6 or month 12.
Glucoregulatory and Inflammatory Factors
Changes in glucoregulatory and inflammatory factors are displayed in Table 2. Fasting plasma glucose did not differ significantly between the intervention groups, or relative to controls, at month 6 or month 12. There were also no significant differences in fasting insulin or the homeostasis model assessment of insulin resistance between the intervention groups at month 6 or month 12. High-sensitivity C-reactive protein and homocysteine levels did not differ significantly between the intervention groups, or relative to controls, at month 6 or month 12. We also performed a sensitivity analysis, in which sex and race/ethnicity were included as adjustment covariates in the intention-to-treat mixed model. The inclusion of sex and race/ethnicity did not affect any of the estimated treatment effects reported in Table 2.
The results of this randomized clinical trial demonstrated that alternate-day fasting did not produce superior adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease compared with daily calorie restriction.
Alternate-day fasting has been promoted as a potentially superior alternative to daily calorie restriction under the assumption that it is easier to restrict calories every other day. However, our data from food records, doubly labeled water, and regular weigh-ins indicate that this assumption is not the case. Rather, it appears as though many participants in the alternate-day fasting group converted their diet into de facto calorie restriction as the trial progressed. Moreover, the dropout rate in the alternate-day fasting group (38%) was higher than that in the daily calorie restriction group (29%) and the control group (26%). It was also shown that more participants in the alternate-day fasting group withdrew owing to dissatisfaction with diet compared with those in the daily calorie restriction group (Figure 1).
Taken together, these findings suggest that alternate-day fasting may be less sustainable in the long term, compared with daily calorie restriction, for most obese individuals. Nevertheless, it is still possible that a certain smaller segment of obese individuals may prefer this pattern of energy restriction instead of daily restriction. It will be of interest to examine what behavioral traits (eg, ability to go for long periods without eating) make alternate-day fasting more tolerable for some individuals than others.
To our knowledge, the present study is the longest and largest trial of alternate-day fasting to date. Previous trials of alternate-day fasting reported weight loss of 3% to 7% after 2 to 3 months of diet.7- 13 Adherence was measured in several previous trials and was shown to be high (eg, participants met their calorie goals on approximately 80%-90% of fast days).7,8,10,11 Most of these past studies provided food on the fast day,7,8,10,11 so the provision of food is not a confounder when comparing past findings with present findings. Food was provided to the intervention participants during the first 3 months of the weight-loss phase to promote adherence26 and show participants the types and quantities of foods that they should be eating. Data from the food records indicated that participants frequently ate extra “nonstudy” foods that were purchased from stores or restaurants.
This finding suggests that limiting caloric intake to approximately 500 kcal every other day may have been difficult for many participants early in the intervention. Future work in this area should examine whether this lack of adherence to alternate-day fasting is due to cognitive, environmental, and/or physiological factors. For instance, measuring changes in subjective appetite (hunger and fullness) in conjunction with modulations in appetite hormones (ghrelin, peptide YY, and glucagon-like peptide-1) could offer some insight into why daily calorie restriction may allow for easier adherence compared with alternate-day fasting.
Contrary to our original hypotheses, the participants in the alternate-day fasting group did not experience more pronounced improvements in risk indicators for cardiovascular disease compared with the participants in the daily calorie restriction group. However, the trial included primarily metabolically healthy obese adults. Since many of the participants had normal cholesterol levels and normal blood pressure at baseline, it is not surprising that most risk indicators for cardiovascular disease did not change in response to diet.
Our study has several limitations. First, the duration of the maintenance phase was short (6 months). Second, the control group was imperfect, in that they received no food, no counseling, and less attention from study personnel, relative to the intervention groups, which may have confounded our findings. We also failed to include the control group in our initial power calculation. Third, since the dropout rate was higher than anticipated, our power to detect the hypothesized difference of 5% weight loss between the intervention groups at month 6 decreased from 80% to 60%. The higher dropout rate in the alternate-day fasting group may have also introduced a possible selection bias between groups.27 Finally, we enrolled predominantly metabolically healthy obese individuals, which may have hindered the abilities of the interventions to produce greater improvements in our measured cardiovascular disease risk indicators.28,29 The generalizability of our findings is also limited by the enrollment.
The alternate-day fasting diet was not superior to the daily calorie restriction diet with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease.
Corresponding Author: Krista A. Varady, PhD, Department of Kinesiology and Nutrition, University of Illinois at Chicago, 1919 W Taylor St, Room 532, Chicago, IL 60612 (firstname.lastname@example.org).
Accepted for Publication: February 26, 2017.
Published Online: May 1, 2017. doi:10.1001/jamainternmed.2017.0936
Author Contributions: Dr Varady had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Drs Trepanowski and Kroeger contributed equally to this work and should be considered co–first authors.
Study concept and design: Kroeger, Varady.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Trepanowski, Kroeger, Varady.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Freels, Rigdon.
Obtained funding: Varady.
Administrative, technical, or material support: Kroeger, Barnosky, Bhutani, Hoddy, Gabel, Rood, Varady.
Study supervision: Varady.
Conflict of Interest Disclosures: Dr Varady reported receiving an advance for the book The Every-Other-Day Diet: The Diet That Lets You Eat All You Want (Half the Time) and Keep the Weight Off, published by Hachette Book Group. No other disclosures were reported.
Funding/Support: This study was supported by grant R01HL106228 from the National Institutes of Health/National Heart, Lung, and Blood Institute and grants P30DK072476 and F32DK107157 from the National Institute of Diabetes and Digestive and Kidney Diseases.
Role of Funder/Sponsor: The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and the decision to submit the manuscript for publication
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Helpful Fasting Information - POSTED ON: Mar 01, 2017
I’ve spent quite a lot of time researching the issue of “Fasting”, and during my studies, I came across the website and YouTube videos of Dr. Jason Fung M.D. in which he shares his comprehensive views about fasting, as well as related issues.
Here at DietHobby my own one-size-does-not-fit-all position is consistently threaded throughout this entire website; and as Dr. Fung shares his preferences and recommendations about food and ways of eating, he makes it clear that he also holds a one-size-does-not-fit-all philosophy.
In his answer to the question: “Why Can’t I Lose Weight”, Dr. Fung says:
“The answer really lies in the multi-factorial nature of obesity.”
“The key to understanding obesity is that many different things can contribute to the development and the treatment. Consider the analogy of your car not starting. There could be multiple problems. For example, the battery is dead, the car ran out of gas, or the spark plugs are worn out. So, if your problem is that the battery is dead, filling up with gas will not help. Neither will replacing the spark plugs. That seems kind of obvious.
But then, websites proliferate about how changing batteries is the cure for cars that don’t start. It is filled with testimonials of how people changed batteries and their cars effortlessly started. Other people attack the website saying that they changed batteries and nothing happened. Instead, they filled up with gas and the car started, so obviously, the key to starting the car is filling up on gas.
That’s exactly what happens in the sad sack, wacky world of weight loss. When you try to lose weight, people assume that there is only one problem for everybody. If your problem is insulin resistance, then reducing carbs may not be the best strategy (intermittent fasting may work better). If your problem is sleep deprivation/ stress, then increasing fibre is not going to be too good.
Cutting sugar works well for those people whose problem is excessive sugar intake. They write books and websites about how sugar is the devil. Others think that is ridiculous and think that refined grains (wheat) is the real devil since they’ve done well reducing grains. Others think that stress relief is the major problem in weight loss. Others blame calories. They all ridicule each other and fill the internet with testimonials. Worse, they all start bickering about how the real problem is carbs, or sugar, or wheat, or calories, or stress, or sleep deprivation, or fibre, or animal proteins etc.
You must understand that they can all be correct. Obesity is not a single problem. There is no single solution. A low sugar diet works amazingly for some, and not at all for others. Just as replacing the battery will work for some cars amazingly and not at all for others.”
For more of this article see Why Can’t I Lose Weight - HTLW12.
Dr. Fung’s website: Intensive Dietary Management, contains a great deal of comprehensive and interesting information which includes an excellent series of articles about Fasting. Below are links which will take you directly to these fasting articles.
Fasting – A History Part I
Fasting Physiology – Part II
Fasting and Growth Hormone Physiology – Part 3
Fasting and Lipolysis – Part 4
Fasting Myths – Part 5
Fasting Regimens – Part 6
Longer Fasting Regimens – Part 7
The Ancient Secret of Weight Loss – Fasting Part 8
Caloric Reduction vs Fasting – Part 9
Women and Fasting – Part 10
Feasts and Fasts – The Cycle of Life – Fasting part 11
Practical Fasting Tips – Part 12
More Practical Fasting Tips – part 13
The Fasting ‘Advantage’ – Part 14
Fasting and Muscle Mass – Fasting Part 15
Fasting Cures Type 2 Diabetes – T2D 4
Fasting Lowers Cholesterol – Fasting Part 16
Fasting and Hunger – Fasting Part 17
Cephalic Phase Response and Hunger – Fasting 18
Bariatrics is Surgically Enforced Fasting - T2D 6
Circadian Rhythms - Fasting 19
Refeeding syndromes – Fasting 20
Obesity – Solving the Two-Compartment Problem – Fasting 21
The Biggest Loser Diet – Eat Less Move More’s Bigger Badass Brother – Fasting 22
Fasting and Exercise – Fasting 23
Fasting and Brain Function – Fasting 24
Fasting and Autophagy – Fasting 25
Power: Fasting vs. Low Carb – Fasting 26
The difference between calorie restriction and fasting – Fasting 27
Why You're Always Hungry – Fasting 28
Fasting and Ghrelin - Fasting 29
Below is a comment by Dr. Jason Fung recently posted in Fung Schweigh, a private Facebook fasting support group.
"First, there is no optimal way to fast. If you do take tea, coffee and broth and have good results, then that is all that matters. If you only get good results with water only, then do water only. There are others that also use sweeteners and bouillon and do well - so great. However, I don't really like the use of artificial chemicals, so i generally do not recommend. There is no 'right' way. Second, I don't think it is necessary to restrict salt during fasting. Third, we help many people with fasting, but they do not get through without problems. We simply try to anticipate the problems (headache, constipation, hunger, cramps) and manage them through it by reassuring them it is normal and giving tips just as this group does."
Information about Dr Jason Fung’s Medical Background:
Dr. Fung grew up in Toronto, Ontario, Canada. He went to the University of Toronto at age 17 to begin studies in Biochemistry. By 23, he completed medical school at the U of T, and began his Internal Medicine residency there.
Finishing his specialty of Internal Medicine, he chose Nephrology (kidney disease) as his sub-specialty. Each field of internal medicine draws its own personalities. Nephrology has the reputation of being a ‘thinkers’ specialty. There are a lot of intricacies of fluid and electrolytes, and he enjoyed these puzzles. He studied Nephrology at the University of California, Los Angeles mostly at Cedars-Sinai Hospital and the VA Wadsworth.
He returned to Toronto in 2001 to start his career in Nephrology, where he still has both an office and hospital practice. Type 2 diabetes is by far and away the leading cause of kidney disease, and he treats many hundreds of patients with this disease. Many also have obesity. By the early 2010s his interest in nutrition, combined with his professional focus on obesity and T2D led him directly to the diabesity puzzle. For more background information, see My Journey.
This is an updated version of an article that I first posted in October 2015.
As new fasting articles by Dr. Fung are becoming available, I am adding those new links and bumping this article up in my blog to make it easy find in DietHobby, under the headings: BLOG CATEGORIES, Fasting. (To see the section, Blog Categories: Look at the right hand side of DietHobby, near the middle of the page.)
Intermittent Fasting & the Dangling Carrot - POSTED ON: Aug 23, 2016
I recently received the comment:
Phyllis Collins, I've been following you and have been a fan of yours.
Have u tried the 24 or 36 hour fasts? Was wondering what your experience was?
I've done quite a lot of experiments with "modified" fasts --- like JUDDD & EOD, and with total water fasting as well. I’ve written quite a lot about this already. To easily find some of them here at DietHobby, …go to the right side of the page about half-way down.... for BLOG CATEGORIES, Fasting, ……where you can easily find past articles I've written about my thoughts and experiences with Intermittent Fasting.
Once you’ve arrived at the “Fasting” category, the best way to find relevant articles is … go to the bottom of that page, below the 5 blog articles, where it says “Page 1 / Page 2 / …. Oldest", and CLICK the link to the Oldest. Then work your way forward, from the past to the present.
Many of my previous blog articles discuss, in depth, my own experiences with various types of intermittent fasting.
The Donkey, the Stick,
and the Carrot,
an allegory applicable
to Intermittent Fasting.
"A farmer wants the donkey to take the load and travel.
But, the donkey does not move.
He hits the donkey with a stick, but it still won’t move.
So, he ties a carrot to the stick and holds it in front of the donkey, just out of reach.
The donkey wants to eat the carrot and moves forward.
At the same time, the carrot also moves by the same distance.
The donkey cannot eat the carrot, till the farmer reaches his destination."
The Donkey is me, or another “intermittent faster”.
The Stick is Fasting = eating zero or very small amounts of food on “fasting” days.
The Carrot is the Promise of eating whatever you want on non-fasting days.
"Just get through today, and tomorrow you can eat whatever you want."
The promise of days of unlimited, unrestricted eating is a Carrot that lures one to an Intermittent Fasting diet, but unfortunately, …for many of us, …. that Carrot proves to be nothing more than an alluring, false promise.
The Truth is that on “tomorrow = the non-fasting days”, you CANNOT eat what you want, in the amounts that you want…unless what you WANT is merely the same as what a naturally thin person consistently eats in order to maintain a normal weight.
Success with intermittent fasting requires the zero, or very-low-calorie, "fasting" days to be balanced together with days of eating at or near one’s maintenance calorie level … in other words, the restrictive days need to occur alongside the kind of “healthy” moderate diet that is followed by the naturally thin.
However, If I WANTED only “normal” amounts of “healthy foods", obesity would never have become a problem for me.
The issue is calorie balance. The calorie number of the fasting day gets added to the calorie number of the non-fasting day with that Total number being divided by 2. When this Averaged calorie amount creates an ongoing calorie deficit, weight-loss will result from the ongoing calorie deficit. However, this ASSUMES that an unmonitored participant would NOT follow a “binge-fast” pattern. For example, a fasting day of 20% with a non-fasting day of 200% (instead of 110%) would be a “binge-fast” pattern, and a calorie Average that would result in weight-gain.
The most extensive scientific research on Intermittent Fasting to date was done by Dr. Krista Varady. This research is frequently quoted by Dr. Jason Fung to support his own fasting viewpoints. For a limited time, a limited number of people “moderately fasted” = i.e. ate 20% of their TDEE on one day, and ate “normally” which turned out to be 110% of their TDEE on the following day.
Personally, I question Dr. Varady’s conclusion that the non-fasting day 110% calorie total was a “naturally occurring” limitation. Since those people KNEW they were being temporarily watched as part of a diet research program, one could reasonably argue that … despite being told to eat “normally” on non-fasting days, they were highly motivated to “not overeat” on “normal” days during that limited time period … which resulted in a modification of the way they would probably choose to normally eat, long-term, when not being watched by scientists.
For larger, younger people – especially males -- whose daily calorie burn is between 2000 to 2500 calories, Intermittent Fasting can be relatively easy…IF… their normal way-of-eating is to “normally” eat around that amount; and …IF…they don’t tend to be “binge-eaters”, which means that they usually only eat VERY-high-calorie on limited special occasions.
However, I am a small, elderly, inactive,"reduced obese", female whose “normal” daily calorie burn is a bit under 1000. It is a continual struggle for me to keep my food intake within that “normal” range, and for me … the reward of getting 1000 to 1200 calories the following day doesn’t seem like much of a Reward after a day of eating only 250 to 500 calories. So, far, despite my best efforts, my results on the up days are often 1500+ calories … which tends to cancel out any weight-loss results of the 250 to 500 calorie “modified-fast” days, … while STILL being FAR LESS than the amounts I really want to eat after a day, or alternate days, of calorie deprivation.
Dr. Jason Fung, M.D. - who is the current medical guru on Fasting - recommends fasting as a fix for “insulin resistance” . However, I do not have any type of Diabetes, and my blood sugars are in the normal range. Although I am a small, “reduced obese”, inactive, elderly female with a very low metabolic rate, I don’t appear to be “insulin resistant”.
Dr. Fung also says the nature of obesity is “multi-factorial”, and that “the key to understanding obesity is understanding that many different things can contribute to the development and the treatment …. Obesity is not a single problem. There is no single solution.”
There is no one perfect “diet” for everyone. My problem is that I find Fasting to be … in and of itself…. "a form of suffering”, and I know that weight that is lost through suffering tends to comes back when I get tired of suffering.
I agree with Dr. Yoni Freedhoff, MD when he says: "If you don't like the life you're living while you're losing, eventually you're going to find yourself going back to the life you were living before you lost. " Doing this will cause your body to re-gain the weight-loss.
Nevertheless, Fasting is an interesting issue. As part of my dieting hobby, I expect that I will continue to learn more about it, and find new ways to experiment with Intermittent Fasting concepts.
Butter Bob Sharing his Opinions - POSTED ON: Apr 12, 2016
New video below:
"Butter Bob" sharing
about Diet & Fasting
Every Other Day - Alternate Day Fasting - POSTED ON: Apr 12, 2016
I modified the graphics and specifics of my current diet experiment....because I can. See day-before-yesterday's April 10 blog for the graphics of my previous plan.
The reason for this modification was that when my (Down) Fast day turns into an (Up) Fed day, I need the following day to be a (Down) Fast day. Otherwise, it seems likely that I'm going to wind up with weeks full of (Up) Fed days.
At present I'm having too many unsuccessful Fast (Down) days to be able to predict exactly which days will be Fed (Up) days and which days will be Fast (Down) days each week. So, for a while, it looks like I'll be jumping back and forth between Week 1 & 2 days at random.
See my April 10 blog to see details of my previous plan.
MY CURRENT PLAN:
My UP days are based on my own personal Total Daily Energy Expenditure (TDEE) which is close to 1,000 calories. Adding 10% brings it up to a total of about 1,100. My plan calls for 3 weekly UP days.
My DOWN days of about 300 calories are close to ¼ (25%) of my TDEE. My plan calls for 3 weekly DOWN days.
1,100 plus 300 equals 1,400 divided by 2 equals 700 calories… Therefore a 2 week rotation of this pattern would result in a total Average calorie intake of 700 calories daily.
I have changed my plan to remove the MEDIUM day of about 700 calories from weekly rotation as I have decided to only include it occasionaly.
I am 71 years old, 5'0" tall, and an inactive, reduced obese female (high weight 271 lbs) who has been maintaining a normal BMI for 10+ years, and my individual TDEE of about 1,000 is low, but not “abnormally” low.
For ME, an average daily intake of 700 calories should create a daily deficit of about 300 calories, and … according to the 3,500 calorie rule… result in a weight-loss of about ½ pound per week.
To bring my calorie counts into proper perspective...
note that the well-known and frequenlty-used Mifflin formula gives an "AVERAGE" person of my age, size, and activity level, a TDEE of 1150 calories, and a BMR of 985.
I've been keeping computer records of my calorie intake & weight every day now for about 12 years, and so I know that my own TDEE is about 100 calories or so below the "AVERAGE".
Women who are younger, taller, heavier, and more active often have very little understanding or knowledge of how low the TDEE is for a short, light, inactive elderly woman... and of course, it is even less for a "reduced obese" one.
For those people who think my TDEE calculation is too low.... HERE's a little personal lesson.
Click this link to get access to one of the online calculators that use Mifflin to determine both BMR & TDEE. If you are a female use it to run your own numbers. After you've done that .... try changing your own age to 71, and moving yourself to "Inactive"... Look at your numbers change. Now, change your height to 5'0".... Quite a difference, right?... Now give yourself ...as an elderly, short, inactive person... a BMI of around 22.5 (which is somewhere near the middle of a "normal" BMI) by setting your weight at 115 pounds.... Now, look at the resulting numbers.... which should be around 985 BMR, and 1150 TDEE.
Jun 15, 2017 DietHobby: A Digital Scrapbook. 1500+ articles and 300+ videos in DietHobby reflect my personal experience in weight-loss and maintenance. One-size-doesn't-fit-all, and I address many ways of eating whenever they become interesting or applicable to me.
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Jan 01, 2017 DietHobby is my Personal Blog Website. DietHobby sells nothing; posts no advertisements; accepts no contributions. It does not recommend or endorse any specific diets, ways-of-eating, lifestyles, supplements, foods, products, activities, or memberships.