Podcast: Fasting Diets: What’s the Skinny?
By: Science Vs
After not eating for a period of time your body runs out of sugars to burn and starts burning more fat for energy. An example in the episode was someone who was burning around 50% fat in normal circumstances went up to 70% after fasting.
To study how much fat is being burned they use a machine that analyzes your breath and the ratio of oxygen to carbon dioxide that you exhale. Fat that’s been burned exits the body through exhaling.
People on fasting diets tend to lose weight. A 5 week study that controlled for calories eaten seems to indicate this isn’t a result of fasting, but that people on these diets tend to eat less calories.
Studies of worms and mice indicate that fasting increases the rate at which cells consume and recycle themselves (called autophagy) and can increase longevity. Studies in humans are mixed and much less conclusive.
Studies in mice indicate that fasting can starve cancer cells (many types of cancer aggressively consume sugar for energy) and make them more susceptible to normal cancer treatments. Studies in humans for this are ongoing.