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Is the Fast Diet Safe?

Jacky Gale | March 7th, 2013

Fad Diets

Most physicians advise patients to stay away from fad diets, which frequently advocate potentially dangerous tactics like self-imposed starvation, and can lead to nutritional deficiencies. But a new trend that is becoming increasingly popular across the pond claims that fasting can actually improve a person’s general health, as well as facilitate weight loss. The Fast diet was created by Dr. Michael Mosley of London in response to some dire news from his doctor. Mosley learned that his fasting glucose levels were abysmal, and with his family history of diabetes, he knew the potential risks of that medical condition.

Mosley’s Fast diet claims to not only help its followers lose weight and keep it off, but it also purports to decrease the risk of cancer, improve cognitive function, and support longevity. However, there’s no denying that any type of fasting is a radical medical choice, and there is no “one size fits all” solution to weight loss. The diets that work are customized to the individual’s needs, such as those offered by the health professionals at The Center for Medical Weight Loss.

Principles of the Fast diet

Mosley’s diet advocates fasting on two randomly selected days of the week. Followers select fasting days that are nonconsecutive. However, the Fast diet does not advocate abstaining from food entirely. Women will eat 500 calories on fasting days, while men are allotted 600 calories. Vegetables, fruit, and lean protein are recommended, and dieters may choose to eat all of their calories in one meal or spread them out throughout the day.

The calorie allotments on these days are below the threshold for what is widely accepted by nutritionists to be a starvation diet: anything below 800 calories. On the non-fasting days, no nutritional guidance is given, and dieters are free to eat as much as they wish of any type of food.

Sample menu for this fad diet

Here is a typical daily menu for a woman following the Fast diet:

Breakfast

  • 1 small apple
  • 1 small mango
  • 1 small boiled egg

Dinner

  • Salad with tuna and beans

Science befind these popular diets

Fad diets that advocate fasting or skipping meals affect the body in several ways. Although a reduction in calories will cause weight loss by forcing the body to burn stored energy for fuel, it’s also important to note that fasting slows the metabolism. A sluggish metabolism means that you’ll burn fewer calories. When you resume eating a normal diet, the metabolism is still lowered, which means that you’re likely to gain back the weight that you lost. Furthermore, returning to a normal diet causes the body to increase the appetite, so you’ll be more likely to overeat. Studies have shown that although fasting on alternate days does indeed cause weight loss, that weight loss was not maintained.

However, another study by a researcher at the University of Illinois revealed that alternate day fasting might encourage lowered levels of LDL cholesterol and blood pressure. This researcher also challenges the idea that fasting leads to later food binging. Clearly, more scientific studies are needed in this area before any reliable conclusions can be drawn.

Is the fasting the best way to lose weight?

Although a periodic fasting diet may work for some, there are some health concerns to take into consideration. Prolonged periods of fasting can lead to nutritional deficiencies, which can cause gallstones, cold intolerance, dehydration, constipation, fatigue and dizziness. Furthermore, even occasional fasting is ill-advised for those with underlying conditions, such as diabetes and other chronic diseases. Women who are pregnant should never restrict calories in this manner.

It’s highly recommended to consult a doctor for a sustainable and safe weight loss program. For many individuals, the best way to lose weight is under the guidance of an experienced physician who is knowledgeable about your medical history and dietary needs. The Center for Medical Weight Loss offers multi-faceted plans that are tailored to each client’s preferences and weight loss goals. The Center has an impeccable track record of proven results, achieved in a safe and sustainable manner. Get started on the path to better health today by finding a Center near you. Simply enter your zip code in the box, and ask about special introductory offers for first-time visitors.


  1. Fast and Famine: Controversial “Fast Diet” Weight Loss Plan Is Eat for 5 Days. http://abcnews.go.com/Health/feast-famine-controversial-fast-diet-weight-loss-plan/story?id=18613821

  2. Fasting Diets. http://www.webmd.com/food-recipes/guide/fasting