Does Alternate-Day Fasting Work for Weight Loss?
Title: Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial
Author: Trepanowski et al
Journal: JAMA Internal Medicine
Objective: To compare the effects of alternate-day fasting vs daily calorie restriction on weight loss, weight maintenance, and risk indicators for cardiovascular disease.
Being overweight or bese increases your risk of essentially every medical problem including diabetes, heart attack, stroke, cancer and much more.
Treating and preventing individuals from developing obesity is an ongoing challenge in the medical community. One of the more commonly prescribed or recommended first steps is caloric restriction. This is built on the fundamental principle of weight loss that if you burn more calories than you consume, you will lose weight.
Adherence to caloric restriction is problematic for a variety of reasons, often resulting in limited success with this approach. For this reason, other approaches and strategies to dietary changes are being investigated.
Various forms of fasting is one such approach that has gained a lot of tractioned in pop culture.
Alternate-day fasting is defined as an approach 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.
The authors of this study wanted to compare alternate-day fasting to a daily caloric restriction diet.
A single-center randomized clinical trial of obese adults (18 to 64 years of age; mean body mass index, 34)
Intervention was participants in 1 of 3 groups for a 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)
- no-intervention control.
The trial involved a 6-month weight-loss phase followed by a 6-month weight-maintenance phase.
The primary outcome was change in body weight. Secondary outcomes were adherence to the dietary intervention and risk indicators for cardiovascular disease.
There were 100 participants. Dropout rate was highest in alternate-day fasting group. (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%]).
There was no difference between weight loss groups at 6 or 12 months. (Difference 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)
Individuals in the alternate-day fasting group struggled to follow protocol, eating more on fasting days and less on feasting days. Those in the caloric 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 (HDL or the good cholesterol) cholesterol levels at month 6 significantly increased among the participants in the alternate-day fasting group but was not significant at month 12. (6 months: (6.2mg/dL [95%CI, 0.1-12.4mg/dL]), 12 months: (1.0mg/dL [95%CI, –5.9 to 7.8mg/dL]).
Mean LDL or low-density lipoprotein. which is the bad cholesterol, was significantly elevated among the participants in the alternate-day fasting group at 12 months. (11.5mg/dL [95%CI, 1.9-21.1mg/dL]) compared with those in the daily calorie restriction group.
Alternate-day fasting did not lead to increased weight loss when compared to classic calorie restricted diet. Another way to say it would be that alternate-day fasting produced equivalent weight loss to caloric restriction.
There were no differences in any of the biomarkers, except the fasting group had higher LDL cholesterol at 12 months.
It’s worth noting that adherence was a problem in this study, especially with the alternate-day fasting group. This made it harder for the authors to draw good statistical conclusions and likely affected the outcome.
Trepanowski, J. F., Kroeger, C. M., & Barnosky, A. (2017). Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults. JAMA Internal Medicine. doi:10.1001/jamainternmed.2017.0936