However, the National Institute of Health took this opportunity to learn some things about metabolism after weight loss, and to determine whether changes in food intake or physical
activity are associated with keeping the weight off vs regaining weight over the long term.
In a previous blog
, we talked about the finding from The Biggest Loser
contestants that 6 years after losing weight on the show, there was about a 500 calorie lower daily calorie burn than what would be expected at their weight 6 years later, which helps to explain why it is so hard to keep weight off after weight loss.
In the most recent publication
, we learn that people who were able to keep weight off 6 years after being on The Biggest Loser
had higher daily physical activity levels than those who experienced
weight regain. Specifically, those who maintained a weight loss of 25% had increased their physical activity by 160% compared to the start of the study, whereas those who weighed more than they did at the start of the study had increased their physical activity by ‘only’ 34% (not enough to offset the decrease in metabolism that happens after weight loss).
Energy intake at 6 years after the show was estimated to be similar between those who maintained weight loss (8.7% less than before the study) vs those who regained weight (still 7.4% less than before the study!). (Scientists: daily energy intake was assumed to be equal to total daily energy expenditure, as weight was reported as stable both at the start of the show, and at the 6 year mark.)
Previous studies such as the LOOK AHEAD study and the National Weight Control Registry
have also suggested that people who are able to keep weight off are those who do more physical activity after weight loss, but in these studies, physical activity was self reported (and we know from other studies that physical activity is over reported). The current study
is the first to use the gold standard of doubly labeled water to measure changes in physical activity several years after weight loss.
Bottom Line: While we know that physical activity is not as important for achieving weight loss, the evidence points to physical activity being very important for maintaining
weight lost over the long term.
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