Muscle weakness and impaired muscle performance was doubled among older adults with vitamin D deficiency. Older adults who exercised had lower likelihood of poor muscle strength and physical performance.

Mice were more motivated to exercise when they had two meals per day, similar to intermittent fasting. Ghrelin is an appetite-promoting hormone that increases during hunger and prompted the mice to exercise.

Polychlorinated biphenyls (PCBs) are chemicals used in industrial materials. PCBs have been found to damage astrocyte function in the brains of mice, which are crucial to neuron and brain function.

Overweight men who exercised before breakfast had double the amount of fat burn compared exercising after eating. Fasting led to lower insulin levels, thus more body fat was used as fuel.