Five-Day Whey Protein Fast

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A five-day whey protein fast is a fad diet plan. This type of elimination diet recommends excluding food groups and eating less than the minimum recommended amount of daily calories for healthy adults – 1,200 calories for women and 1,400 calories for men per day, according to the University of Maryland Medical Center. Excluding food groups from your diet makes it difficult to meet your body’s nutritional needs. Consult your medical professional before going on a fast or fad diet to avoid health complications.

Whey Basics

Whey protein is a highly digestible form of protein from milk. Athletes and other fitness enthusiasts take whey protein as a dietary supplement to improve muscle strength. You can also find whey protein as an ingredient in food products such as bread and baby formula. (Ref 4)

Fasting Basics

On a strict fast, you eat no food and drink only water, tea or natural juice for one to five days, according to information from Some fad diets, including the whey protein fast, use the word “fast” because you stop eating all foods except the few specified in the diet plan. Fasting requires taking it easy and getting rest because you don’t eat enough calories to do all the activities you normally would. Fasting lacks the clinical evidence to prove its efficacy, according to information from

Fasting and Fat Storage

Occasional fasting might promote future weight gain instead of weight loss, according to a study on rats from the Medical University of Gdansk in Poland in the October 2011 issue of “Nutrition.” The researchers put the rats on a three-day fast eight times over a period of four months. In between the fasts, the rats ate a low-calorie diet. The results show the combination of fasting and a low-calorie diet triggers the production of a gene that promotes fat storage. This finding might help explain why people who go on and off fad diets instead of making healthy lifestyle changes often gain back the weight they lose.

Sparing Lean Muscle

Fasting with whey protein might help you spare lean muscle during weight loss, according to a study from the Veterans Administration Medical Center in Minnesota, published in the March 2008 issue of “Nutrition and Metabolism." In the 12-week study, subjects only consumed 500 calories per day, including two whey protein drinks or a low-calorie ready-to-mix beverage. The resulting data show subjects in both groups lost a similar amount of weight. However, the whey protein group lost significantly more body fat and significantly less lean muscle mass than the low-calorie drink group.