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Alternate-Day Fasting (ADF) as a Weight Loss Strategy

Alternate Day Fasting

Restricting your daily intake of calories is one of the most common weight loss strategies, but this popular method has a major drawback: following a low calorie diet day after day can make you feel hungry and uncomfortable, and you might not be able to stick to your diet long enough to reach your weight loss goals. That's where the Alternate-Day Fasting (ADF) Diet, also known as the Every-Other-Day Diet, comes in.

With alternate-day fasting, dieters have a fast day followed by a feast day. On the fast day, they drastically limit their caloric intake; on the feast day, they can usually eat whatever they want, which allows them to feel normal again. Now, you might expect people to binge on the feast day to make up for the calories they missed the previous day, but research suggests that is not the case.

Scientific Basis of the ADF Diet

In a study led by Dr. Krista Varady, an associate professor of nutrition at the University of Illinois, a total of thirty-two overweight and normal-weight adults were randomly assigned to either an ADF diet group or a control group. During the 12-week study period, those in the ADF group consumed 25% of their baseline energy needs on each fast day, and then ate ad libitum on each alternating feast day. All fast day meals, ranging in energy content from 400 to 600 calories, were prepared in the metabolic kitchen of the Human Nutrition Research Center at the University of Illinois, and each fast day meal had to be eaten between 12 p.m. and 2 p.m. Those in the control group were permitted to eat ad libitum every day.

The results of this randomized controlled trial, published in Nutrition Journal, were promising: at week 12, weight loss in the ADF group was 11.5 lbs relative to the control group. Compared with the controls, those following the ADF protocol also lost more body fat and showed improved risk parameters for cardiovascular disease. The researchers concluded that alternate-day fasting appears to be promote weight loss and improve cardio-protection in normal-weight and overweight adults but added that further trials with larger sample sizes are still warranted.

The randomized controlled trial described above was performed to specifically investigate the weight loss effects of alternate-day fasting in non-obese people, but there are also a number of preliminary studies that have evaluated the effects of ADF diets in obese people. In their report describing the findings of their randomized controlled trial, the team of scientists led by Dr. Varady also summarized the findings of earlier studies that have investigated the benefits of alternate-day fasting in obese individuals: according to Dr. Varady and colleagues, ADF diets have been shown to result in 5 to 6% reductions in overall body weight and about 2 to 3 inch reductions in waist circumference in obese adults in just 8 to 12 weeks.

Where to Learn More About Alternate-Day Fasting

Krista Varady, PhD, is an associate professor of nutrition at the University of Illinois and the world's leading researcher into alternate-day fasting. Her studies have appeared in numerous prestigious journals, and she has discussed her breakthrough findings with lifestyle magazines such as Elle and Men's Health. Dr. Varady has also published a compelling book on the topic called The Every-Other-Day Diet. Available through Amazon here ( if you live in the US) or here ( if you live in the UK), this accessible and informative book explains in detail how the ADF Diet works and provides practical tips and recipes to help you get started.