“Physical activity or exercise in a sufficient dose aids in long-term weight maintenance.”
This is a pretty well-established fact, however, the authors hasten to point out that the key term in this “Fact” is the term “sufficient dose”.
Thus, the authors note that,
“Physical-activity programs are important, especially for children, but for physical activity to affect weight, there must be a substantial quantity of movement, not mere participation.”
Indeed, recent studies have questioned whether in fact, the amount of physical activity that is achievable in school phys-ed programs (for example) would provide a sufficient dose to prevent weight gain (let alone maintenance of weight loss).
Thus, this “Fact” reflects the consistent body of knowledge that exercise as a way to control your weight, be it to prevent weight gain, lose weight, or prevent weight regain, requires a substantial dose of activity – more than is perhaps necessary to simply maintain good health (see Obesity Fact #3).
As I have said before, exercise is perhaps best seen as part of energy-in rather than energy-out and the right dose of exercise to help you control your weight is just the amount that it takes to RUIN your appetite. For some people that may well be the benefit you get from walking your dog.