Does Taking Diet Breaks Impact Muscle or Fat Loss?

Does taking intermittent diet breaks affect body composition compared to continuous calorie restriction?

Overview

• What did they test? In this study, researchers compared the effects of following a continuous calorie deficit to an intermittent calorie deficit that incorporated diet breaks on weight loss and body composition over 12 weeks. Participants following the continuous deficit (CON) maintained a 25% calorie reduction below maintenance for the entire 12 weeks, while the intermittent deficit group (INT) maintained a 25% deficit with one refeed day each week at maintenance calories, and one full refeed week every 6 weeks at maintenance calories.  
• What did they find? There was a significant reduction in fat mass and body fat % in both groups with no differences between groups despite the INT group reporting significantly greater calorie intake and a smaller calorie deficit. There was also a trend towards greater preservation of fat-free mass in the INT group, but the differences between groups were not significant. 
• What does it mean for you? The results of this study show that taking a diet break for one day each week and for one week every 6 weeks did not impact fat loss among individuals maintaining a 25% energy deficit. These findings suggest that occasional breaks from calorie restriction to eat at maintenance calories may be a viable strategy for increasing dietary adherence without impacting body composition outcomes.

What’s the Problem?

Obesity remains one of the most pressing public health challenges worldwide. While calorie restriction is the cornerstone of most weight loss interventions, long-term success is often limited by physiological adaptations to dieting that include reductions in resting metabolic rate and the loss of fat-free mass 1. These adaptations can make continued weight loss more difficult and increase the likelihood of weight regain. Intermittent calorie restriction strategies that incorporate planned refeeds and diet breaks have been proposed as a way to preserve lean mass and reduce these metabolic adaptations while still promoting fat loss 2. But there is limited research directly comparing these approaches to date, particularly in women. 

Purpose

The purpose of this study was to compare the effects of 12 weeks of continuous calorie restriction (CON) to intermittent caloric restriction (INT) incorporating one planned refeed day each week and a weekly refeed every 6 weeks on body composition in women with obesity. 

Hypothesis

The authors hypothesized that the INT group would experience similar fat loss while preserving fat-free mass during the intervention.

What Did They Test and How?