“Our findings suggest that this group of successful weight-loss maintainers are consuming a similar number of calories per day as individuals with overweight and obesity but appear to avoid weight regain by compensating for this with high levels of physical activity,” said Victoria A. Catenacci, MD, a weight management physician and researcher at CU Anschutz Medical Campus.
The study looked at successful weight-loss maintainers compared to two other groups: controls with normal body weight (Body Mass Index (BMI) similar to the current BMI of the weight-loss maintainers); and controls with overweight/obesity (whose current BMI was similar to the pre-weight-loss BMI of the maintainers). The weight-loss maintainers had a body weight of around 150 pounds, which was similar to the normal weight controls, while the controls with overweight and obesity had a body weight of around 213 pounds.
This study is one of the few to measure total daily energy expenditure in weight-reduced individuals using the gold standard doubly labeled water method. This method allows researchers to precisely determine an individual’s energy expenditure through collecting urine samples over one to two weeks after people are given a dose of doubly labeled water. Doubly labeled water is water in which both the hydrogen and the oxygen atoms have been replaced (i.e. labeled) with an uncommon isotope of these elements for tracing purposes.
The measure of total daily energy expenditure from doubly labeled water also provides an estimate of energy intake when people are weight stable, as they were in this study. Prior studies used questionnaires or diet diaries to measure energy intake, which have significant limitations.
The researchers also measured each individual’s resting metabolic rate in order to understand how much of the total daily energy expenditure is from energy expended at rest versus energy expended during physical activity. Prior studies used self-reported measures or activity monitors to measure physical activity, which are techniques that cannot provide the same accuracy.
The findings are consistent with results from the longitudinal study of “The Biggest Loser” contestants, where physical activity energy expenditure was strongly correlated with weight loss and weight gain after six years.