Researchers suggest that taking 2-week breaks from dieting could increase weight loss.
Study leader Nuala Byrne, a professor in the School of Health Sciences at the University of Tasmania in Australia, and colleagues recently reported their findings in the International Journal of Obesity.
It is estimated that every year, around 45 million people in the United States go on a diet, primarily with the aim of losing weight.
But, as many who have dieted will be well aware, sticking to a diet plan 7 days per week can be a challenge. The new study, however, suggests that we should not feel guilty about taking a short break from dieting, as it may actually help with weight loss.
Prof. Byrne and colleagues came to their findings by enrolling 51 obese men aged 25 to 54 years who were a part of the Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound study.
As part of the study, the men were randomly assigned to one of two diet groups. One group was required to follow a continuous calorie-restricted diet for a total of 16 weeks.
The men in the other group followed the same calorie-restricted diet, but they took 2-week breaks during which they increased their calorie intake enough to keep their weight stable. This cycle was repeated for 30 weeks, meaning that they also engaged in 16 weeks of dieting in total.
Greater weight loss with intermittent dieting
At the end of the study period, the researchers found that the men who took 2-week breaks from dieting lost more weight than those in the continuous diet group.
What is more, the team found that 6 months after ceasing the calorie-restricted diet, men who had engaged in intermittent dieting had maintained a weight loss of around 8 kilograms more than men who continuously dieted.
The researchers say that their findings indicate that a 2-week on, 2-week off approach to dieting may be more effective for weight loss and maintenance than continuous dieting.
Prof. Byrne and colleagues speculate that poorer weight loss as a result of continuous dieting may be down to a flurry of biological mechanisms that are triggered by calorie restriction.
"When we reduce our energy (food) intake during dieting, resting metabolism decreases to a greater extent than expected," explains Prof. Byrne, "a phenomenon termed 'adaptive thermogenesis' - making weight loss harder to achieve."
"This 'famine reaction,' a survival mechanism which helped humans to survive as a species when food supply was inconsistent in millennia past, is now contributing to our growing waistlines when the food supply is readily available," she adds.
A 'superior alternative' to continuous dieting?
Prof. Byrne notes that previous research has shown that intermittent diets that use 1-7-day periods of partial or total fasting may be no more effective for weight loss than continuous dieting.
One study published in JAMA Internal Medicine this year, for example, found that obese adults who engaged in alternate-day fasting lost no more weight than those who engaged in daily calorie restriction.
With this in mind, Prof. Byrne suggests that the 2-week break period used in their study may be "critical" to the increased weight loss observed.
"While further investigations are needed around this intermittent dieting approach, findings from this study provide preliminary support for the model as a superior alternative to continuous dieting for weight loss."
Prof. Nuala Byrne