Fasting Diets

By Candace Chemtob

Dieting is a national obsession. Each year more than forty-five million Americans embark on a weight-loss diet. Athletes are not immune to the pressures to attain an “ideal” weight. After all, performance benefits are associated with increased lean body mass and lower levels of body fat. Weight loss, however, can have unintended negative effects on athletic performance and on overall health and well-being.

Misinformation and the unsubstantiated claims of weight loss programs complicate an already difficult process. The truth gets lost in an industry where governmental oversight is lacking and manufacturers are free to market products without scientific evidence. The latest fad is fasting diets which have convinced believers that starvation is the best cure for diabetes and hypertension and will give you a longer life.

The practice of fasting has roots in ancient religious rituals. Buddha practiced fasting and extreme austerity for six years on his road to enlightenment. Jesus fasted for forty days and nights in the desert. Mohammad told his followers the path to paradise is “stick to fasting, there is no equivalent.” Today’s starvation diets are fasts that demand extreme self-restriction of food intake.

Cleansing or detoxification programs are diets consisting of fresh fruit juices with low calorie fluids such as broth and tea. As the name implies, these diets claim to flush the toxins out of the body. But the truth lies far from the claims. The National Institutes of Health states that “there isn’t any evidence that detox or cleansing programs actually remove toxins from your body or improve your health” and goes on to warn these diets may present health risks: there might be contamination with potentially harmful ingredients or bacteria; fasting may not lead to lasting weight loss; and fasting can cause fainting or dehydration. An effective alternative to cleansing is to limit your exposure to known toxins such as mercury, cigarettes, alcohol, nitrosamines and BPA.

Gaining devotees is the Fasting Mimicking Diet and other starvation diets that allow small amounts of food. The University of California diet calls for five days of fasting per month (food and drink are restricted to roughly 1,000 calories per day) and the rest of the month intake is unrestricted. There are other fasts that are twelve hours per day, one day on/one day off and even up to seven days with no food. Fasts are promoted as a way to reduce health risks, such as diabetes and heart disease, and to live a longer life. This is a stretch of the truth as the research in humans only looked at a three-month diet, and most of the research on fasting has been conducted in animals.

So where does this leave the athlete, looking for a way to achieve a healthy weight and peaking their performance. Without all the hype, here are some practical tips to serve as a starting point:

1     Weight loss efforts for children, pregnant and breastfeeding women and for individuals with eating disorders and metabolic diseases (such as diabetes) should be medically supervised.

2     Determine your healthy weight. Go to to calculate your body mass index (BMI).  A healthy BMI range is 18 to 25. For elite athletes, because BMI does not account for varying degrees of lean body and fat mass, advanced techniques to measure body composition are recommended.

4     Timing is everything. Lose weight in the off season. Dieting depletes glycogen stores quickly which is the major storage form of carbohydrate storage in the body. When glycogen stores are depleted, blood sugar levels drop quickly and performance plummets.

5     Be patient. Gradual weight loss (one to two pounds per week) may protect muscle mass. For an athlete, a loss in muscle mass can translate into a loss of strength and speed.

6     Not all calories are created equally. Don’t simply count calories and leave yourself short on nutrients. The nutrient quality of the food you eat is key to being healthy.

Fad diets seem exciting and new, but there is plenty of research proving that more traditional methods of weight loss (slow, gradual weight loss while consuming a healthy balanced diet) leads to dramatic reductions of cardiovascular disease, cancer, and diabetes. Common sense would suggest that it is not best to experiment on oneself.

Healthy eating and exercise are synergistic. Exercise is key. “If I had to rank behaviors in terms of priority, I’d say that exercise is the most important thing associated with living longer and healthier,” said Dr. Luigi Ferrucci, a NIH physician who oversees research on aging and health. “Exercise is especially important for lengthening active life expectancy, which is life without disease and without physical and mental/thinking disability.” So, pick up your racquet, enjoy our sport, eat well and live healthy. This may be the secret to a long healthy life.