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Obesity and Weight Management

Juice fasting?

12/21/2007

Question:

I have been a consistent exerciser for at least 10, but due getting some more available time I have upped my workouts just enough to start losing some weight and get back to my target BMI (I needed to lose 8 pounds, I`ve got four to go). I have friends that are trying to talk me into a 20-day juice fast, but they are trying to make up for poor exercise and eating habits in a hurry. Are these juice fasts at all useful?

Answer:

Juice fasts, and any other fast, can be 'useful' in that you will lose weight. However, you usually take in so few calories that you put yourself in starvation mode. When this happens, your body slows its basal metabolic rate (BMR) and also tends to use your muscle instead of your fat stores as its source of energy that it needs beyond the calories in your juice diet.

Juice diets generally aren't as satisfying as a diet that contains solid food, either. When you actually have something to chew, you are more satiated than when you just drink your food. At the end of the 20 days, you are apt to regain the weight that you lost. Some of it was just water weight that you lost when your body used muscle for energy instead of fat. When you lose about 4 pounds through starvation, you lose about 1 pound of muscle and about 3 pounds of water trapped in the muscle.

Why do you regain? Because you return to eating more calories, and your body still has a slower BMR. With a slower BMR you are ingesting more calories than you expend. The body deposits the extra calories as fat, and you gain weight. You are better off sticking to your healthy eating pattern of solid food and continuing the exercise that you are doing. Slow weight loss is much more apt to keep the pounds off.

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Response by:

Sharron   Coplin, MS, RD, LD Sharron Coplin, MS, RD, LD
Former Lecturer
Food & Nutrition
College of Education and Human Ecology
The Ohio State University