Claims

A 2001 Queen's University review of exercise intervention studies found that after 20 weeks, 'the amount of exercise energy expenditure had no correlation with weight loss,' demonstrating that exercise does not reliably cause weight loss as commonly claimed.

Exercise increases muscle mass and improves insulin sensitivity, setting up a healthier body composition, but these effects may not manifest as weight loss if diet is not managed, leading to discouragement if weight loss is the primary expected outcome.

Exercise causes muscle gain and muscle tissue contains mitochondria that burn energy, making exercise 'the single best thing you can do for yourself,' but it should not be expected to produce weight loss on the scale.

Morning exercise can dial down cortisol levels and keep them down for the rest of the day, completing the stress response cycle and preventing chronic cortisol elevation.

Frequent exercise allows the body to become much better at reacting to stress, presumably through repeated practice completing the stress-exertion cycle and building cortisol resilience.