Exercise for weight loss?
There are plenty of good reasons to exercise but how important is exercise to losing weight?
To answer this question I will quote from Dr. Peter Attia:
It seems intuitively obvious that it should be important, but experimental trials of diet vs. diet plus exercise invariably show that the exercise makes effectively no difference on weight loss.
The world is full of overweight and obese people who work at physically demanding jobs — hard-working laborers, for instance, who exercise regularly and are even devoted to it and remain just as obese or overweight as ever. I know, personally, many folks (including myself) who have gained significant weight, despite hours of rigorous daily exercise.
This isn’t controversial, by the way. It’s this research that led the American College of Sports Medicine and the American Heart Association in their last physical activity guidelines (2007) to make this statement: “It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling.” (And one of the co-authors of this ACSM/AHA report is an exercise physiologist who described himself as “short, fat and bald” when he started running 30 years ago, and since then has run 85,000 miles, or the equivalent of more than three times around the globe at the Equator, while only becoming “short, fatter and balder,” in his own words.)
There are definite health benefits to exercise including stronger bones and muscles, but it's not clear that exercise leads to any effective long term weight loss. Evidence shows that with more exercise you will become more hungry and eat more.
So why bother exercising?... It is not clear from the studies how much exercise to mix with a fasting regimen. On and off exercise might help maintain muscle growth. But an honest answer is that the experts don't know yet.
Here are a few more thoughts - more anecdotal than scientific:
1) Exercise can feel good and that can help with the motivation to lose weight. Runners, dancers and rock climbers will feel lighter and that feels good.
2) Exercise might help with overall energy levels. Exercise might lead to a more efficient metabolic system because the body will be ready to cope with stress.
3) More muscle means more storage capacity of glycogen. The body stores glycogen in both the liver and in muscle tissue. This means that a strong person has a larger storage capacity for glycogen and less glucose is being converted into fat. Diabetics tend to have better glucose control when they exercise.
While exercise is good, I am not a believer in boot camp style weigh-loss that risks injury. Major changes in weight come from major changes in nutrition. If your work out leads to injury and exhaustion - then your overall health could be at risk. A sensible approach involves light exercise with an emphasis on fasting and eating whole fresh foods when eating.