[Skip to Content]
[Skip to Content Landing]
Views 95,349
Citations 0
Original Investigation
May 1, 2017

Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese AdultsA Randomized Clinical Trial

Author Affiliations
  • 1Department of Kinesiology and Nutrition, University of Illinois at Chicago
  • 2Nutrition Obesity Research Center, University of Alabama at Birmingham
  • 3Department of Epidemiology and Biostatistics, University of Illinois at Chicago
  • 4Quantitative Sciences Unit, Stanford University, Stanford, California
  • 5Nutrition Obesity Research Center, Pennington Biomedical Research Center, Baton Rouge, Louisiana
JAMA Intern Med. Published online May 1, 2017. doi:10.1001/jamainternmed.2017.0936
Key Points

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.

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.

Trial Registration  clinicaltrials.gov Identifier: NCT00960505

×