What is Diet Cycling and Does it Work?
Diet cycling, also known as intermittent energy restriction, is a method of body fat loss that involves dieting for a period of time and then weight maintenance for a period of time. This cycle is repeated over and over until a goal weight is achieved. The hopes are to decrease muscle loss and resultantly to decrease loss in metabolism. Diet cycling is a method some people used to try to decrease muscle loss during dieting. In the MATADOR Study (link below), researchers divided people with the disease of obesity into two groups. One group did a continuous calorie restriction for 16 weeks. The other intermittent group would calorie restrict for two weeks then have a balanced calorie intake for two weeks. They repeated this cycle for 30 weeks. The intermittent group lost fat more efficiently. This meant when they were losing weight it did not come as much from the muscle tissue but came more from the fat tissue.
Why is it so important that we try to maintain as much muscle mass during weight loss as possible? There are multiple reasons but one of the main reasons is because lean body mass (which includes muscle mass) is one of the key factors in determining our metabolism. The more lean body mass a person has the higher their metabolism. So, if we are trying to decrease weight regain after weight loss, we want lean body mass (including muscle mass) to be as high as possible in order to have a higher metabolism. Unfortunately, when we lose weight our body undergoes metabolic adaptation which means our metabolism will fall because the body is trying to maintain its weight against our efforts.
Statistically, when people lose weight, most people regain their weight.
• At 1 year, 70% of people relapse to their initial weight.
• At 2 years, 85% of people relapse to their initial weight.
• At 3 years, 95% of people relapse to their initial weight.
• 1/3 to 2/3 add back more weight than their initial start weight.
So what happened to the contestants of the Matador study? 6 months after they had finished their diet interventions both groups re-gained weight but the intermittent group regained less weight. Fat mass was significantly lower than baseline in the intermittent group but in the continuous group it was not significantly lower.
When you try to lose weight should you try intermittent energy restriction? Maybe. We are in the infancy of this research but hopefully we get more clues as to how long a person should intermittently energy restrict and how much.