Intermittent Fasting – What the Science Says
- September 19, 2019
Intermittent fasting diets are currently one of the world’s most popular health trends. They have gained considerable popularity in recent years, as some people find these diets easier to follow than traditional calorie restriction. Intermittent fasting is an umbrella term for various diets that cycle between periods of fasting and non-fasting. The diet doesn’t specify which foods you should eat, but rather when you should eat.
Types of Intermittent Fasting Diets
Common intermittent fasting practices involve daily 16-hour fasts or fasting for 24-hours, twice per week. Three main types of intermittent fasting diets exist:
- The 16:8 method, which involves skipping breakfast and restricting daily eating to 8-hours, then fasting for 16-hours in between.
- Whole day fasting (also known as the 5:2 diet) that involves one or two fasting days per week, with an allowance of 500-600 calories during those days.
- Alternate-day fasting is the strictest form and involves fasting for 24-hours, once or twice a week.
Recent findings suggest that various types of intermittent fasting diets are equally as effective as calorie restriction for weight loss. A handful of small studies in overweight and obese individuals show significant beneficial effects of intermittent fasting on blood pressure, blood sugar levels, weight loss, and percent body fat reduction. Healthy non-obese individuals have also been shown to lose a significant amount of weight and body fat, while maintaining normal resting metabolic rate (i.e., intermittent fasting did not lower metabolism). However, this was only a 22-day study and self-reported hunger did increase, staying constantly elevated, throughout the study. This decreases the likelihood of long-term adherence to the intermittent fasting; a big issue with most fad diets.
Complex physiological mechanisms regulate body weight and resist weight loss. Many diets, even the most divergent ones, are capable of a degree of short-term success, with some diets leading to marginally greater losses than others over periods of several months. However, it’s the long-term that really matters. Effective diets for weight loss need to be established over years to decades. The best guidance on healthy eating and losing weight comes from the U.S. Department of Agriculture’s ChooseMyPlate.gov website. Also check out my 9 Ways to Lose Weight and Be Healthy.