A study just out in the prestigious JAMA did not find benefits of IF compared to the more traditional approach. (1)
Another recent study (2) following the popular 5:2 IF schedule vs a calorie matched restricted calorie diet, yet again, found no statistically significant differences in endpoints studied, which was weight weight cardiometabolic factors:
“Intermittent energy restriction was as successful in achieving modest weight loss over a 24-month period as continuous energy restriction.”
The study ran a full year and followed over 100 people. The Abstract is posted blow.
Intermittent Fasting (IF) continues to be a popular approach to weight loss. It’s not a new approach, and most of my comments HERE still hold up. Since that vid, a number of studies in humans have been done, and the effects have not been impressive. The study below, the largest to date, that ran 50 weeks, did not find major differences in weight loss, and other endpoints looked at.
I’m not ready to dismiss IF per se, as there’s still more questions then answers but controlled studies continue to fail to demonstrate benefits. In the second study, in obese non-exercising people, a 5;2 IF protocol was not superior to calorie matched diet for weight loss. The next step would be comparing different IF protocols. For example, perhaps the 5:2 approach may not potentiate endocrine adaptation as well as other approaches, or maybe different protocols will be more effective for different populations. Fact is, we don’t have the answers at this time, and what exists for human studies small and or short term.
Also, what impact does IF have on performance or strength? Does a strength or physique athlete respond differently to IF than say an endurance athlete? What about lean vs people with higher bodyfat levels? There’s still plenty of Qs to be answered regarding IF…
Bottom line at this time: find the approach you find most beneficial to your goals, but don’t fall for IF being a magical approach to fat loss, cuz it’s not. It’s still about the calories. Some recent thoughts on calories vs exercise worth a read HERE also as well as understanding the 3,500 calorie myth HERE.
(2) Effects of intermittent and continuous calorie restriction on body weight and metabolism over 50 wk: a randomized controlled trial
The American Journal of Clinical Nutrition, Volume 108, Issue 5, 1 November 2018, Pages 933–945,
Will Brink is the owner of the Brinkzone Blog. Will has over 30 years experience as a respected author, columnist and consultant, to the supplement, fitness, bodybuilding, and weight loss industry and has been extensively published. Will graduated from Harvard University with a concentration in the natural sciences, and is a consultant to major supplement, dairy, and pharmaceutical companies.
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