Week on, week off intermittent dieting appears to be effective for weight loss and maintenance.
Intermittent energy restriction or the “week on, week off“ weight loss diet continues to gain popularity as a weight loss strategy. The problem is that prior to recent research, there is limited evidence to back this method of weight loss and the biggest claim against it is that this method fails to teach you to maintain weight loss. The long-term viability Of this method of dieting has been suspect to salt he least.
Research from 2020 looked at the question of intermittent versus continuous calorie restriction and weight loss maintenance. The objective of the study was to follow up with participants 12 months after they had completed a 12-month dietary intervention trial involving continuous energy restriction and two forms of intermittent energy restriction; a week-on-week-off energy restriction and a 5:2 program, assessing long-term changes on weight, body composition, blood lipids and glucose.
The study enrolled 109 overweight and obese adults that aged 18–72 years and attended a 12-month follow-up after completing a 12-month dietary intervention intended to induce weight loss. The test groups included involving three groups: continuous energy restriction (1000 kcal/day for women and 1200 kcal/day for men), week-on-week-off energy restriction, and a 5:2 (500 kcal/day on modified fast days each week for women and 600 kcal/day for men). The primary outcome was weight change at 24 months from baseline and secondary outcomes of change in body composition, blood lipids and glucose.
For the 109 individuals who completed the 12-month follow-up, weight decreased over time with no differences between week-on and week-off and continuous energy restriction or 5:2 and continuous energy restriction. The maintenance follow up showed significant weight loss in all groups, but the average weight loss maintained was higher in the continuous weight loss group. It was just not significantly different. The weight loss ranged from 5-10 pounds not the average. Total cholesterol reduced over time and glucose, HDL, LDL and triglycerides were unchanged.
This study is promising because it shows that all diets were successful if maintained. I think the continuous would have been significantly better if there N were large enough. This is a small study and the low N likely played a part in the lack fo significance.
The bottom line: Intermittent energy restriction was as successful in achieving modest weight loss over a 24-month period as continuous energy restriction. I believe that continuous would have found superior with significance if the N were higher. I would recommend finding a diet that works for you. A larger study is needed to clarify the results.