Little difference between alternate day fasting and calorie restriction

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A randomised clinical trial demonstrated that alternate-day fasting did not produce superior adherence, weight loss, weight maintenance or improvements in risk indicators for cardiovascular disease compared with daily calorie restriction.

Alternate day fasting regimens have increased in popularity because some patients find it difficult to adhere to a conventional weight-loss diet.

Dr Krista A Varady, of the University of Illinois at Chicago, and co-authors included 100 obese adults in the single-centre trial, which was conducted between October 2011 and January 2015. Patients were assigned to 1 of 3 groups for one year: alternate-day fasting (25% of calorie needs on fast days; 125% of calorie needs on alternating “feast” days); daily calorie restriction (75% of calorie needs every day); or no intervention.

After one year, weight loss in the alternate-day fasting group (6.0%) was not significantly different from the daily calorie restriction group (5.3%), according to the results.

“The results of this randomised clinical trial demonstrated that alternate-day fasting did not produce superior adherence, weight loss, weight maintenance or improvements in risk indicators for cardiovascular disease compared with daily calorie restriction,” the article concludes.

The authors note some study limitations, which included a short maintenance phase of six months.

Abstract
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 [11] 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.

Authors
John F Trepanowski, Cynthia M Kroeger, Adrienne Barnosky, Monica C Klempel, Surabhi Bhutani, Kristin K Hoddy, Kelsey Gabel, Sally Freels, Joseph Rigdon, Jennifer Rood, Eric Ravussin, Krista A Varady

JAMA material
JAMA Internal Medicine abstract


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