Just like the chicken-and-egg debate, people have wrestled with the question of which is more important for those who have lost weight and want to keep it off: adhering to a strict diet or exercising more. Now, researchers are closer to the answer, thanks to the TV show “The Biggest Loser.’’

A study of contestants led by a Veterans Affairs Medical Center researcher who 11 years ago lost 108 pounds herself on the reality show found those who kept up with a rigorous exercise program were better able to keep the pounds from returning.

The show features people with obesity competing with each other to lose the most weight over 30 weeks through intense diet and exercise. The 14 participants in the study lost an average of 127 pounds.

Six years after appearing on the show, the contestants had kept off a median of 13 percent of their original body weight. But those who had stepped up their exercise a lot, in some case by about 160 percent, kept off more weight. The contestants who regained weight, mostly body fat, had only boosted their exercise by around 34 percent. In both groups, the food intake was roughly the same.

This supports the belief, the researchers said, that the key to losing weight is dietary intake, while exercise is more important in maintaining the weight loss. This may not always be easy. People would have to engage in 80 minutes of moderate activity or 35 minutes of vigorous exercise every day to meet those marks, and that level of activity might not fit into everyone’s busy lives.

But fighting the disease of obesity requires a lifelong commitment and a strong exercise program is a vital key to success.