Strategy to Lose Weight Over the Long Term
A small study on the participants of The Biggest Loser helps to understand why, after a diet, some reget fat and others do not.
Why it’s important
It is quite easy to lose weight by dieting. The difficulty is not to take them back. Why do some succeed and some do not? A study of participants in the American reality TV show The Biggest Loser, in which overweight or obese competitors seek to lose the most pounds, provides an answer: the activity physical would make the difference, but after the phase of slimming, not during.
What the study says
The authors of this study, published in Obesity magazine, began to follow participants as soon as they were selected for the game. Initially, the 14 participants weighed an average of 149 kg and at the end 91 kg, almost 60 kg less. To lose all those pounds, they had gone through a 30-week diet and exercise program.
The authors took measurements at the time the participants of the show were chosen, then 6 weeks, 30 weeks and finally 6 years after the start of the show. At the beginning, when people lost weight, it was fewer calories, more than exercise, which explained that some people lost more than others.
But 6 years later, their average weight has risen to 132 kg, only 17 kg below their starting weight. However, there was great variation among the participants: for example, one of them continued to lose weight, while five people almost regained their starting weight.
The researchers shared the participants in two groups: those who had gained weight and those who had maintained themselves fairly well (seven people who on average had finally lost 37 kg). Instead of asking the participants questions about their physical activity, a method considered unreliable, the researchers used another strategy to know if they were doing a lot of work: they made them drink a water in which hydrogen atoms and of oxygen were replaced in part by stable isotopes. The isotopes of oxygen were found in the exhaled carbon dioxide. The more calories you spent, the greater the amount of exhaled carbon dioxide.
Results: Those who had best maintained their weight had increased their physical activity by 160%, compared with 34% of those who had gained weight. Energy intake was similar between the two groups. According to Kevin Hall, one of the authors, those who managed to maintain their weight loss compensated for the decline in metabolism through physical activity.
However, this is a small observational study, the results of which should be interpreted with caution. But at least one other study conducted with the same method confirms these observations, that of Schoeller during which the level of physical activity at the end of the weight loss phase was associated with fewer pounds resumed a year later. Other studies ( see below ) have also found that the new weight is better maintained when you are physically active at a more sustained level. It appears that it is necessary to maintain at least one caloric expenditure of 11 kcal / kg / day via exercise to avoid regaining lost weight. In practice, after a weight loss achieved by dieting whatever it is ( low-calorie diet, low-carb diet type Atkins, paleo diet, ketogenic diet, vegetarian diet ,etc…), it can be judicious from the end of the weight loss phase to opt for an exercise program. On average, in Kevin Hall’s study, those who managed to maintain significant weight loss had done the equivalent of 80 minutes of moderate physical activity a day like walking, or 35 minutes of intense exercise like of running . This is more than the usual recommendations of 150 minutes a week of moderate activity and 75 minutes of intense activity.
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