How much weight lifting or other exercise is optimal for fitness? What is the right amount of carbohydrate restriction or fasting for sustained weight loss and health? What level of exposure to allergens will reduce allergies? How many hours of sun tanning is healthy? How frequently should plus lenses be worn to reduce myopia? Do I need to take cold showers every day to get their benefit? How much stress is enough — and how much is too much?
Many of the questions I get on this website and the forums are of this type. People understand the general concept of hormesis, namely that exposure to controlled amounts of stress can be beneficial, because it elicits beneficial adaptive responses in the organism. They understand that weight lifting builds muscles, and that intermittent fasting and calorie reduction can be healthful. But too much of any stressor — weight lifting, caloric restriction, sunlight, allergens — can have adverse consequences. With hormesis, it seems, the Goldilocks principle applies: to get a benefit, the level of stress must be “just right”. And because it’s so easy to veer into overload, many people seek to avoid even mild stress: Avoid allergens. Cover up with sunscreen. Eat frequent small meals. Don’t exert yourself. But if you choose this path, you forgo the possible hormetic benefits.
So how do you determine the optimum level and frequency of exposure to a stress? And how much rest or recovery between exposures is optimal? Read More