Does fasting or calorie restriction make the skin look younger?

Animal research shows that calorie restriction protects the skin in several ways: it suppresses inflammation, strengthens antioxidant defences and supports stem cells in the skin. As a result, it slows both ordinary ageing and damage caused by sunlight. However, this has so far been demonstrated almost exclusively in laboratory animals. Studies in which people specifically fast or restrict calories and in which skin ageing is measured as an outcome are virtually non-existent.

Intermittent fasting activates mechanisms in the body that break down harmful oxygen radicals and clear away waste products. In animal research this works consistently. In humans there are some indications that oxidative stress decreases, but those effects are modest and the question of whether that produces any visible change in your skin remains unanswered.

In mice that followed a fasting period every two months from the midpoint of their lives, both the number of skin lesions and the risk of cancer fell. A small pilot study in humans showed improvements in risk factors for ageing, but the skin was not specifically examined. These are therefore promising first steps, but not yet proof that your skin will look younger as a result.

A concrete example of a nutrient that stimulates the cellular clean-up process (autophagy, the same process that fasting activates) is nicotinamide, a form of vitamin B3. This supplement has been studied in humans for the prevention of non-melanoma skin cancer, with positive results. That is, however, specifically for cancer prevention, not for making the skin look younger. The literature on the effect of fasting on skin conditions is sparse and of variable quality. If you have a skin condition and want to fast, discuss this with your doctor first.