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Input: "Did they cut more calories from their diet ... or did they become more physically active?" asked study author Kevin Hall   a senior investigator with the National Institute of Diabetes and Digestive and Kidney Diseases.
 Hall  had been "puzzled by how quickly the contestants were losing weight." So he contacted the show's physician and began studying the season eight contestants.
Early on   Hall  observed that weight loss was better predicted by food intake  not physical activity alone. But in the long term  the opposite was true.
"You have to be very physically active in order to keep the weight off  " Hall  said.
 Hall 's findings echo previous studies that promote more exercise for long-term weight loss maintenance. However  experts caution that doesn't mean people can neglect their diets in the long run  either.
This method  however  was not able to tell how much of the physical activity was due to normal daily activities -- like cleaning the house or walking the dog -- versus following a workout plan   Hall  said.
Six years later  however  the contestants' resting metabolisms still hadn't sped back up   Hall  showed in a study last year.
For  Hall   metabolic changes are just one part of the puzzle. Genetics may also play a role  as well as social factors that can make it hard for some people to incorporate so much exercise in their daily lives.
 Hall  added that it's not necessarily those who were most physically active during the competition who kept it up six years later.

How some 'Biggest Losers' keep the weight off