Intermittent Fasting: Unlocking Weight Loss and Athletic Gains ... But is it Right for Everyone?
By Orthopedic Surgeon James Slauterbeck, MD
Intermittent fasting is an eating pattern that alternates periods of fasting with periods of eating. A typical intermittent fasting regimen involves fasting for 16 to 18 hours, such as finishing dinner by 6 p.m. and not eating again until 10 a.m. or noon the next day. During fasting periods, water, black coffee, black tea, and herbal tea are permitted and do not break the fast. Green tea is often recommended to help curb hunger. Artificial sweeteners can be used but probably should be limited.
Is intermittent fasting effective for weight loss?
Intermittent fasting is effective and safe for most adults seeking weight loss. Clinical trials and meta-analyses show that intermittent fasting can help people lose 3 to 8 percent of their starting weight over several months. Intermittent fasting works by helping the body switch from burning sugar to burning fat, which may also improve cholesterol, blood pressure, and other markers of metabolic health. This strategy is especially effective for individuals who prefer to focus on meal timing and healthy eating rather than counting calories or tracking specific foods. I have found that intermittent fasting is most successful in those who choose non-processed foods and avoid calorie-dense foods during eating periods, maximizing weight loss and metabolic benefits.
Is intermittent fasting recommended for athletes?
For athletes and physically active individuals, intermittent fasting does not necessarily impair performance and may offer additional benefits. Research shows that intermittent fasting, combined with exercise, can lead to significant weight and fat loss without reducing muscle mass or strength. Most studies find no negative effects on aerobic capacity, strength, or power, and some evidence suggests time-restricted eating may improve aerobic fitness.
What is the effect on adolescents or those with chronic conditions?
Caution is needed for adolescents and people with chronic medical conditions such as diabetes. In adolescents, intermittent fasting may interfere with normal growth, insulin production, and hormone balance, and could increase the risk of metabolic problems and disordered eating behaviors. Many experts recommend that adolescents avoid unsupervised intermittent fasting and instead focus on a balanced, healthy diet. For people with diabetes, intermittent fasting can help with weight loss and may improve some metabolic markers, but it is not superior to standard calorie restriction for blood sugar control. Intermittent fasting can increase the risk of low blood sugar (hypoglycemia), so anyone with diabetes who wants to try intermittent fasting should do so only under medical supervision.
In summary, intermittent fasting is a flexible and effective approach for weight loss and can be safely used by many adults and athletes, but it is not recommended for adolescents or people with diabetes without medical supervision. The key is to find a healthy eating plan that fits personal needs and health conditions, and to seek guidance from a healthcare professional before making significant dietary changes.
James Slauterbeck, MD, is an orthopedic surgeon whose special interests include sports medicine, adolescent sports medicine, female sports medicine, and high school and college athletic injuries. He is affiliated with UNC Health Orthopedics at Southeastern Health Park and UNC Health Southeastern. To learn more, call (910) 738-1065 or visit https://www.unchealth.org/care-services/doctors/s/james-r-slauterbeck-md.
