Exercising without dieting was shown to be as effective for modest weight loss as dieting without exercising, in this latest study. To summarize:
Researchers in Canada studied 52 men with abdominal obesity, in which most of a person's body fat is in the stomach region.
The men where divided into four different study groups:
At the beginning and the end of the 12-week study period, investigators measured the men's weight, total body fat, proportion of body fat in the abdomen, body muscle, physical fitness, and early signs of diabetes.
On average, men in both the diet and the exercise-weight loss programs lost about 16 pounds. The weight of the men in the other two groups did not change, but all men who exercised, even the ones who did not lose weight, experienced an increase in physical fitness.
"Our findings are in stark contrast to previous observations. Although we reaffirm that diet restriction is effective for reducing total and abdominal obesity, our findings also demonstrate that 12 weeks of approximately 60 minutes of daily exercise without caloric restriction is associated with substantial reductions in body weight," the authors report.
Annals of Internal Medicine July, 2000;133:92-103.
Some improvement is probably due to increased metabolic rate from exercise (e.g., improved glucose tolerance, increased hormone sensitivity).
Some improvement could also be due to improved mental state (e.g., improved self-esteem, decreased depression, etc) which exercise has the ability to do.
It is very important to know that one hour a day seems to be a critical threshold. There are two previous articles that have been posted which describe this quite elegantly. One new concept though is that the one hour does not need to be continuous. It can be split up into two or three slots per day.