Rest Periods Probably Do Not Increase Weight Loss

Researchers at the University of Tokyo claim that they have shown that intermittent exercise will help you to lose more weight than continuous exercise at the same intensity. Seven men participated in three different trials: 1) one hour at an intensity equal to 60 percent of maximum oxygen uptake; 2) 30 minutes at the same intensity followed by a 20-minute rest, followed by 30 more minutes of exercise at the same intensity; and 3) one hour of rest. The trial with two bouts of 30 minutes separated by a 20-minute rest burned the most fat. This intermittent exercise trial resulted in higher blood free fatty acid, glycerol and epinephrine levels, and significantly lower values of insulin and glucose.

If these researchers are correct, scientists may need to revamp their ideas about the best exercise regimen for weight loss, recommending multiple bouts of exercise with intermittent rest periods. However, there may be another way to explain the results of this study. Fat cells release fat during exercise and then reabsorb some of that fat during rest. During the intermittent exercise trial, fat cells would release fat in the first bout of exercise, some of the released fat would return during the rest period, and then during the second bout of exercise, the fat cells would appear to have released more fat because they released new fat and some of the more-soluble fat that had returned to the fat cells. The increase in fat loss would be due to the fat that had re-entered the cells during the rest period, and would not make any difference in total weight loss.

Unless the researchers can show that intermittent exercise burns more total fat than continuous exercise, there is no need to change your exercise routine. Weight loss is determined by how hard and how long you exercise, not by the timing of your rest periods. Journal reference; more on exercise for weight loss