Intermittent dieting works best, but not the 5:2 kind
Avoiding continuous dieting may be the key to losing weight and keeping it off, say nutrition scientists, but traditional intermittent fasting regimens such as the popular 5:2 diet are not the way to do it.
The findings from a randomised controlled trial, including 51 obese men, show that taking a two-week break from energy restriction appears to be critical to success.
Those who take a break from dieting lose on average 47% more weight than the continuous dieters and 80% more weight at six-month follow-up.
The results are in stark contrast to previous studies, which have reported no advantage to intermittent dieting over continuous dieting.
In the current study, intermittent dieters achieve “superior weight loss”, the researchers say.
Two groups of participants took part in the 16-week trial, which cut calorie intake by one-third.
One group maintained the diet continuously while the other dieted for two weeks and then stopped for two weeks, eating simply to keep their weight stable, and repeated this cycle for 30 weeks to ensure 16 weeks of dieting.
The researchers report that those in the intermittent diet group not only lost more weight, but also gained less weight after the trial finished.
“Although both groups regained weight post-intervention, weight loss (reduction from baseline) was on average 8.1kg greater in the intermittent group than the continuous group at six-month follow-up,” they write in International Journal of Obesity.
This suggests that interrupting dieting with energy balance ‘rest periods’ may reduce compensatory metabolic responses and, in turn, improve weight loss efficiency, says lead author Professor Nuala Byrne, head of the University of Tasmania's School of Health Sciences.