Continued exercise appears to be essential in stopping previously obese people from regaining weight they have lost, new research indicates.
It is well known that although obese people can rid themselves of excess weight, very few can successfully maintain themselves at that lower weight.
But some do, and the secret is exercise such as bike riding.
The study, published in the March issue of Obesity, found that those exercising after they had lost weight were consuming the same amount of kilojoules as those that were obese.
However, they were not regaining weight because they were burning those kilojoules off by exercising.
Those that were keeping their once obese bodies at lower weight undertook almost twice the physical activity per day as the obese individuals in the study.
"This study addresses the difficult question of why so many people struggle to keep weight off over a long period. By providing evidence that a group of successful weight-loss maintainers engages in high levels of physical activity to prevent weight regain – rather than chronically restricting their energy intake – is a step forward to clarifying the relationship between exercise and weight-loss maintenance," said Danielle Ostendorf, PhD, a postdoctoral fellow at the CU Anschutz Health and Wellness Center.
The findings reveal that successful weight-loss maintainers rely on physical activity to remain in energy balance (rather than chronic restriction of dietary intake) to avoid weight regain.
In the study, successful weight-loss maintainers are individuals who maintain a reduced body weight of 13.5 kilograms or more for over a year.
"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.
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 labelled water.
Doubly labelled water is water in which both the hydrogen and the oxygen atoms have been replaced (i.e. labelled) with an uncommon isotope of these elements for tracing purposes.
The measure of total daily energy expenditure from doubly labelled water also provides an estimate of energy intake when people are weight stable, as they were in this study.
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.