Physical activity is crucial in order to maintain substantial weight loss – and more important than a person's diet.

That is the finding of a study by the University of Colorado Anschutz Health and Wellness Center (AHWC), published in the March issue of Obesity journal (to access the full article, click here).

The survey found 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.

For the purposes of the study, researchers classed "successful weight-loss maintainers" as individuals who maintained a reduced body weight of 30 pounds or more for over a year.

The study looked at successful weight-loss maintainers compared to two other groups: controls with normal body weight (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 total calories burned (and consumed) each day by the weight-loss maintainers was significantly higher (300 kcal/day) compared with that in individuals with normal body weight controls – but was not significantly different from that in the individuals with overweight/obesity.

Notably, of the total calories burned, the amount burned in physical activity by weight-loss maintainers was significantly higher (180 kcal/day) compared with that in both individuals of normal body weight and individuals with overweight/obesity.

Despite the higher energy cost of moving a larger body mass incurred by individuals with overweight/obesity, weight-loss maintainers were burning more energy in physical activity, suggesting they were moving more.

The finding was supported by the weight-loss maintainer group also demonstrating significantly higher levels of steps per day (12,000 steps per day) compared to participants at a normal body weight (9,000 steps per day) and participants with overweight/obesity (6,500 steps per day).

“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, researcher at AHWC.

Danielle Ostendorf, a postdoctoral fellow at AHWC, added: "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."