Discusses the role of exercise in supporting autophagy in times of protein restriction.
Exercise while Dieting
Lack of sufficient exercise underlies many of the diseases of aging, especially diabetes and cardiovascular diseases. It is particularly important that we maintain a minimal level of exercise when in the protein or calorie restriction phase of protein cycling or ADCR. We feel weaker in a period of restriction and may, consciously or unconsciously, ease up. Human muscles are very adaptable and, if no demands are made on them, they shrink. When they shrink, the amino acids in their proteins become available to other cells and this could counter-act the intended autophagy-inducing affect of protein or calorie restriction.
Exercise should address three areas: strength, endurance and stretching. Strengthening muscles (pull-ups, push-ups, weight lifting, etc.) informs the large muscles to maintain or increase their mass. Aerobic endurance exercise (walking, running, swimming, cycling, etc.), where the heart rate is noticeably increased, maintains the mass of the heart and the small muscles involved with breathing. Finally stretching avoids cramps and other discomforts that might otherwise dissuade us from exercising at all.
Exercise also warms you up. One way the body responds to reduced calorie intake is reduced calorie output. Most of the calories we consume are used merely to keep the body at a constant 98.6 ºF. Simply by constricting blood flow to the skin, for instance, the body can conserve heat and reduce calorie output. Or the body can tell your brain that you are feeling a bit chilled and should put on a sweater. Or it may simply cause you to hold your arms in more tightly. However it happens, the net result is that reduced calories in leads to reduced calories out rather than to weight reduction. If weight reduction is your goal, then you may need to consciously override these unconscious decisions. This may be as simple as dressing lightly and using fewer bedclothes and cultivating an appreciation of how then feeling cool is helping you to lose weight. Generally, body awareness is good in any diet plan whether you want to lose weight, gain weight or just stay as you are.
Recent evidence shows that exercise itself is an autophagy inducer at least in muscle cells and that the benefits of exercise depend on its induction83.