What You Need to Know About Alternate Day Fasting

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With everyone hyping on intermittent fasting lately, you may have considered trying it but worry that you won't be able to stick to a fasting schedule every single day. According to one study, though, you can take days off of fasting and still reap all the benefits of fasting.

Meet: alternate day fasting (ADF).

Researchers at the University of Illinois at Chicago put a group of obese volunteers on either a 25-percent-fat diet or a 45-percent-fat diet. All participants practiced alternate day fasting, alternating between days of eating 125 percent of their calorie needs and days of fasting, in which they were allowed to eat up to 25 percent of their metabolic needs during a 2-hour window.

The Perks of Alternate Day Fasting

After eight weeks, both groups lost significant amounts of weight—without losing muscle mass—and reduced visceral fat, the deadly fat that surrounds your internal organs. The higher-fat diet also had better compliance and lost more weight. That's not a huge surprise since fat adds palatability to meals. I have seen my clients consume meat, avocados, olive oil, and other high-fat foods that add more calories to meals yet still result in an average of five pounds of weight loss a week, along with improved cardiovascular risk and body fat composition even without fasting. (See: Yet Another Reason to Eat More Healthy Fats.)

So if you're interested in losing weight, you may not need to change the type of diet (ex: low-fat or high-fat) that you already follow—just change your eating pattern. And if you decide to try alternate-day fasting, you may be able to do so without complete deprivation on fast days and still lose weight. (Not all weight-loss plans work for everyone, including alternate day fasting or intermittent fasting. Find the best time to eat to lose weight for you.)

What I thought was interesting, as it may shed light on a metabolic phenomenon that we do not fully understand, is that despite the 50-percent calorie deficit over a two-day period, volunteers maintained lean body mass instead of losing muscle. (Here's more on how to build muscle while burning fat.)

The Downsides of Alternate Day Fasting

Fasting or ADF isn’t for everyone. For one, there may be differences in how men and women respond to fasting. You should also be wary of fasting if you have a health issue that requires you eat regularly (such as diabetes) or have a history with an unhealthy or disordered relationship with food, as we reported in Everything You Need to Know About Intermittent Fasting.

My clients ask me all the time, “What diet should I follow?” and my reply is always the same: The diet you choose should be one that you will enjoy the most. If you enjoy a low-fat diet, then this is your answer. If you like higher fat-foods, lower your carbs and you will feel content and be healthy with these choices. You will stick to the plan you have chosen because you like the food. It is a "winning" decision (and will surely help you stick to your healthy eating goals).

And if you’re thinking about alternate day fasting, my question to you is: If you could eat a little more food than you needed on one day, would you be able to manage eating an extremely small amount of food the next day?

Nationally known as an expert in weight loss, integrative nutrition, blood sugar, and health management, Valerie Berkowitz, M.S., R.D., C.D.E. is co-author of The Stubborn Fat Fix, director of nutrition at The Center for Balanced Health, and consultant for Complete Wellness in NYC. She is a woman who strives for internal peace, happiness and lots of laughs. Visit Valerie's Voice: for the Health of It or @nutritionnohow.