Registered Dietitian, Board Certified in Sports Nutrition, Food Scientist

Intermittent Fasting – Hype or Worth Talking About?

Intermittent fasting has received some attention lately with regards to weight loss. This type of approach restricts eating food and caloric containing beverages for an extended period of time, typically for at least 16 hours. There are animal studies and preliminary human studies to indicate this approach might improve a number of health outcomes including those risk factors related to diabetes, cancer and heart disease. However, additional human studies, including those that are long-term, are needed to determine health benefits, particularly as it compares to other calorie restricted diets. Regardless, this type of dietary approach has gained momentum; and thus, many who combine this with exercise for weight loss have jumped on the band-wagon. The question remains whether this is a good approach.

In general, prolonged restriction of food and beverages is harmful to health and negatively affects exercise performance. One would suspect that intermittent fasting would lead to the same conclusion, but this is not always the case in elite athletes and is still a matter of debate. A limited number of studies have investigated the impact of athletic performance on elite athletes who observe fasting for religious purposes, such as Ramadan where one requires a total abstention of food and drink from sunrise to sunset. The results are inconclusive as to whether there is an impact on physical performance and how this could affect the outcome of the competition. Much of this may depend on the individual and their ability to adapt. In addition, athletes who maintain their total caloric and nutrient intake during non-fasting periods, training regimen, body composition and sleep schedule are less likely to suffer from a negative impact on performance. Regardless, coordination of exercise and training with the coach, athletic trainer, and registered dietitian is critical for competitive athletes.

For the everyday active individual, intermittent fasting may present some challenges and may not be the best approach. Work-outs may suffer and one may even feel light-headed, dizzy, tired, and nauseated. A low caloric intake will not help to sustain a hard work-out. Staying well fueled with a balanced diet of fruits, vegetables, low-fat dairy, whole grains, and lean protein can optimize your performance when exercising. Making lifelong, well-balanced dietary choices can assist in achieving a healthy weight, optimizing nutritional status, and enhancing one’s exercise plan. Meeting with a registered dietitian can assist in developing a personalized, dietary approach to keep you healthy and active.