Published in the journal Obesity, researchers from the University of Colorado Anschutz Health and Wellness Center compared those who had already lost weight and maintained it for a year (and weighed around 150 pounds) to two other groups of people: those with a normal body weight (around 150 pounds, similar body mass of weight loss maintainers) and those who were overweight (around 213 pounds, similar BMI to what the weight loss maintainers had before they lost weight).

Participants’ total daily energy expenditure (TDEE), or the amount of calories they burned, were measured through urine samples. Their metabolic rates were also measured in order to know much of their TDEE each day came from resting versus physical activity.

During the course of the study, all of the groups maintained their weight-meaning that the total energy expenditure, or the number of calories they burned per day, was equal to the amount of calories they took in.

The researchers found that total energy expenditure in the weight loss maintainers was greater than those of the normal weight group, and similar to that of the overweight group.

© Park Feierbach According to new research published in the journal Obesity, physical activity may help you maintain weight loss better than diet alone.

This suggests that the people who had lost weight before and kept it off were taking in a similar amount of calories as the overweight group.

So why weren’t the weight loss maintainers gaining it all back? The researchers believe it comes down to their increased level of physical activity: The weight loss maintainers burned about 300 calories more a day than those who were a similar weight-180 of which came from physical activity.

For one, the weight loss maintainers were taking more steps per day than everyone else-12,100 versus 8,900 (normal bodyweight group) and 6,500 (overweight group).

When a person loses weight, their body experiences several metabolic adaptations that attempt to get their body back to their starting weight, said study coauthor Danielle Ostendorf, Ph.D., a postdoctoral fellow at the Colorado University Anschutz Health and Wellness Center. You burn fewer calories at a lower body weight than a heavier wight. So you either have the reduce your calorie intake or increase your calorie burn (through physical activity)-or a combination of the two-to keep the weight off.

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“Based on our study’s findings, it appears as if the successful weight loss maintainers are relying more on energy expenditure through physical activity rather than a reduction in their caloric intake,” she told Runner’s World.

The bottom line? Exercise is just as important as diet when it comes the maintenance phase of losing weight, if not more so. However, Ostendorf points out that everyone is different.

“Some individuals can maintain weight loss successfully through diet and not as much physical activity, whereas others may require very high levels of physical activity,” she said. “The best strategy is the one that works for that individual, so trying different things to see what works can be an important step to successfully maintaining weight loss longterm.”