Intermittent fasting: consuming fewer calories but in a different way.

Intermittent fasting has become quite common in recent years. What is it and how is it done? Does it really lead to weight loss? A quick insight into intermittent fasting was given at EASD 2020 by Prof. Krista Varady (University of Illinois, Chicago, USA).

Intermittent fasting is an umbrella term for 3 types of dieting. First, there is alternate day fasting where 1 day you restrict your consumption to about 500 kcal and the next you eat normally. Second is the 5:2 diet, which means 1 or 2 days of fasting followed by 6 or 5 days of normal eating. On fast days, only about 50 kcal are allowed. The third type of intermittent fasting involves eating only during a certain time period each day, usually a 4- to 10-hour window. During that time, people can eat whatever they like, but outside the window, they only consume water or zero-calorie drinks. Tests of the alternate day fasting regimen resulted in a 10-15 pound weight loss in 3 months. The time-restricted eating method also results in weight loss, but only 5-10 pounds in 3 months. Time-restricted eating is easier to follow, however, because it does not require counting calories. A study of time-restricted feeding (8-hour window) in obese individuals showed an average 3% weight loss over 3 months, high (80%) self-reported adherence, and unintentional calorie restriction of around 350 kcal/day. Under this diet, systolic blood pressure decreased, but there was no change in plasma lipids or glucoregulatory factors. Shorter feeding windows (4-6 hours) resulted in similar outcomes, but with higher unintentional calorie restriction (550 kcal/day) and 3% weight loss in 2 months. Intermittent fasting should not be attempted by pregnant women, people who have binge eating disorders, shift workers, and those given to frequent snacking. Those who wish to try intermittent fasting should be advised that the first 10 days can be rough, with headache being the most common complaint. Consuming 50 grams of protein on a fast day helps to reduce hunger.

1. Varady KA. Clinical application of intermittent fasting. EASD 2020. Session: We are what we do not eat.

Posted on 14 December 202017 December 2020