Researchers have largely assumed that reduced food intake drove these benefits by reprogramming metabolism. But a new study from University of Wisconsin–Madison researchers finds that reduced calorie intake alone is not enough; fasting is essential for mice to derive full benefit.
The new findings lend support to preliminary evidence that fasting can boost health in people, as trends like intermittent fasting continue to hold sway. These human and animal studies have added to the growing picture of how health is controlled by when and what we eat, not just how much.
The research further emphasizes the complexity of nutrition and metabolism and provides guidance to researchers trying to untangle the true causes of diet-induced health benefits in animals and humans.
The researchers discovered that, combined with eating less, fasting reduces frailty in old age and extends the lifespan of mice. And fasting alone can improve blood sugar and liver metabolism.
Surprisingly, mice that ate fewer calories but never fasted died younger than mice that ate as much as they wanted, suggesting that calorie restriction alone may be harmful.