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Should you try fasting for weight loss?

fasting for weight lossFasting—close cousin to “detoxing” and “cleansing” plans—is oh so popular these days. Does it make sense? Should you try fasting for weight loss?

I’m about to tell you when I think fasting is a terrific strategy.


If you are a religious believer and your faith calls for fasting as a spiritual practice at specific times of year, go for it.

As a Roman Catholic, I fast on Ash Wednesday and Good Friday. My friends in the Byzantine Rite follow much more stringent requirements. The Jewish tradition includes numerous official fast days, including Yom Kippur.

And if you’re a faithful Muslim, you observe the month of Ramadan. No doubt many other religions have fasting traditions as well.

What’s my point? The purpose of fasting is mortification—that is, the denial of bodily passions and appetites.

But fasting as a weight-loss strategy?

Girlfriend, do NOT go there.

Why fasting is an utter failure for fat loss

I’m going to give you four reasons why fasting is a fail if you care about permanent weight control. Yes, I know it might sound like a great way to zap off pounds quickly, but the dangers of fasting greatly outweigh any benefits.

1. It is a great way to lose “weight” if you don’t care what kind of weight you’re losing. In other words, if you don’t mind losing muscle along with the fat, be my guest! The quick initial weight loss you get from a day or two of fasting is mostly water and glycogen (a form of carbohydrate stored in your muscles and liver). If you persist in regular fasting, you lose muscle, fat, and water.

Muscle equates to shape, increased metabolism, and strength. Thus, when you lose muscle on a diet, you’re becoming smaller but also flabbier, weaker, less sexy, and more prone to regain because muscle loss means fewer calories burned.

2. Eating too little—or nothing—reduces your metabolic rate. Numerous studies bear this out, and I’ve written about it extensively. So for now I’ll just say that “very low calorie diets” and fasting spur what’s popularly called the “starvation response.” Your body deduces that food is in short supply (that is, it’s experiencing a famine) and scales back on energy requirements as a way of keeping you alive longer.

Some recent scientific research shows that this metabolic slowdown can last at least a year after the starvation diet ends. Scary, huh?

3. Fasting can lead to bingeing. For many people, extreme food deprivation spurs overeating. Your blood sugar drops, you feel like crap, any kind of food starts looking really good, and the next thing you know, your face is buried in a bag of crisps. The sad thing? You probably blame yourself for a lack of “willpower.”

4. Cutting out food entirely, even for a day or two a week, is not the way to learn healthy eating habits. One of my biggest beefs with most name-brand diets is that they are not sustainable. You just can’t fast for the rest of your life (nor can you cut out all carbs or all fats or subsist on shakes, etc.).

I love to cite the U.S. National Weight Control Registry, which tracks thousands of successful “losers.” One of the key characteristics of these people is that they developed smart, sensible eating habits while taking off the pounds—and they continue the same strategy (with additional calories) in maintenance.

I know you want quick results

Look, I know you’re tired of wearing those extra pounds. But the slow method—losing a pound or two of fat, not muscle, per week, without reducing your metabolism—is the way that gives the best chance of permanent success.

Fasting is the fast way to disappointment and weight regain.

Not so appealing, really, is it?

Please share your thoughts in the comment box!

Mary C. Weaver, CSCS

I'm a weight-loss and body-transformation coach for women---and I want to share my best weight-loss strategies with you! Click the link to learn more about my Body-Transformation Bootcamp program!

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