To handicap the obesity race, we have to understand obesity.
I) You can't really lose the weight by exercise, and diets don't work long-term
"In general, for weight loss, exercise is pretty useless," says Eric Ravussin, chair in diabetes and metabolism at Louisiana State University and prominent exercise researcher. The scientific evidence on this has reached consensus. You would have to exercise for an hour and a half to burn the effects of half a muffin, and exercise has a tendency to make you hungrier and make you want to reward yourself with food. Most people cannot exercise to an extent that makes a difference in terms of weight loss.
As for diets, if the goal is lose to keep the weight off long-term, they are a disaster. 80% of people who purposefully lose weight through diet put it back within a year, and within five years, according to Dr. Rudolph Leibel, a recognized expert on obesity at Columbia, that number is between 95 and 98%.
The weight usually comes back plus 5-10 pounds. "Researchers at the University of California at Los Angeles analyzed 31 long-term diet studies and found that about two-thirds of dieters regained more weight within four or five years than they initially lost." Dr. Kelly Brownell at Yale University, premier obesity researcher, called this "yo-yo dieting."
As for why, studies show that when people lose weight through dieting their metabolism slows, exercise is less effective and they need fewer calories to put on weight. Their hormones change, causing increased hunger. People report feeling preoccupied with food. Most dieters quickly regain the weight when the diet stops. More recent studies suggest that these post-diet changes may never go away until the weight is back on.
Of course, 2-5% manage to keep the lost weight off long-term. Those tracked by scientists
