More than 2 of every 3 adults nationwide are overweight or obese. Excess weight raises your risk of developing serious health problems, including heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.
A healthy diet and regular physical activity helps you lose weight. However, keeping the weight off is difficult for many people. Body weight reflects a complicated balance between the amount of energy consumed (calories) and the amount of energy used by the body. Researchers have been working to understand which aspects of diet and physical activity are most important for weight control.
Is weight loss dependent on exercise, diet or both?
To find out, Dr. Kevin D. Hall of NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) studied participants in a season of “The Biggest Loser,” a televised weight loss competition. Of 16 competitors enrolled, 14 participated in a follow-up study 6 years later. After losing an average of about 132 pounds during an intensive 30-week diet and exercise period, many of the participants regained a substantial amount of weight after the program was over. But there was great variation among them.
The researchers explored how physical activity and diet affected weight maintenance. At the beginning, week 6, and week 30 of the competition, as well as 6 years afterward, the team measured the participants’ body fat, total energy expenditure, and resting metabolic rate, the energy burned during inactivity. To calculate each participant’s level of physical activity, the scientists subtracted the resting metabolic rate from the total energy expenditure. They determined the calorie intake by using the observed weight and body fat changes along with the total energy expenditure measurements.
Weight: Experimental Results
Six years after the competition, seven participants had maintained an average weight loss of about 25% of their starting weight. The other seven returned to a weight that was within 1% of their starting weight. The calorie intake of both groups was similarly reduced from before the competition began.
The main difference was in levels of physical activity. The weight loss maintainers increased their physical activity by an average of 160% from before the competition began, while those who regained their weight had only a 34% increase.
These results clearly show that while both exercise and diet are important, maintaining the weight loss results from significantly more physical activity.