Intermittent fasting is a dietary strategy that allows for varying windows of time where no calories (either from food, drink, or supplements) are consumed. By itself, intermittent fasting is a protocol that does not direct attention to what foods are being consumed. Instead, intermittent fasting shifts focus to when calorie intake is occurring. The time windows where feeding is restricted are flexible, and can vary depending on a person’s health goals, their experience level with fasting, and logistical considerations such as work schedule, etc. Longer fasts are not necessarily always superior, nor is any given fasting structure going to be optimal for all people at all times. Some common fasting patterns people follow are: one 24 hour fast once a week, two to three 18 hour fasts in a week, or four+ sixteen hour fasts in a week. When not fasting, one eats normally, without attempting to further reduce calories. The fasting windows are usually combined with the sleeping hours to make the fasts feel shorter. For example, a person who eats his or her last meal of the day at 5pm, goes to bed, and then waits until 5pm the next day to eat again, has undergone a 24 hour fast.
Many find that one of the biggest advantages to intermittent fasting is its convenience and flexibility. It is a protocol that is simple and robust, and doesn’t suffer from many of pitfalls and restrictive parameters that other eating plans suffer from. From a practical standpoint, intermittent fasting is also cheap (fasting is free), and time-saving (fewer meal prep and feeding times).
Intermittent fasting has been shown, in most cases even without alterations in subject’s macronutrient or diet quality, to improve several important biomarkers of health. Despite conventional dietary fears of “slowed metabolisms”, intermittent fasting shows significant improvement in glucose control and fat loss. Intermittent fasting windows also give the gut and body time to heal from the stresses of digestion, up regulate cellular repair and maintenance procedures such as autophagy, and allow for a systemic reduction in inflammation. This allows for greater nutrient utilization and absorption during mealtimes. Fasting also prioritizes the preservation and growth of lean muscle mass, whereas dieting through regular caloric restriction methods often provokes a decline in muscle mass.
While the benefits of intermittent fasting may seem compelling on their own, they become even more effective when combined with other strategies such as ketogenic dieting, nutrient dense foods, and strength/hypertrophy training.