Addressing Intermittent Fasting Questions

Intermittent fasting continues to trend as an option for weight loss. Be prepared to explain what it is and when it might help.

There are various types of intermittent fasting. The most common methods involve consuming under 25% of energy on fasting days (alternate-day fasting), restricting energy intake 1-6 days weekly (periodic fasting), or eating only during a certain time frame each day (time-restricted feeding). All methods generally result in reduced calorie intake. Time-restricted feeding is often touted online. But how much time should be spent eating vs fasting is often up for debate – research has evaluated up to 16 hours of fasting daily.

Tell patients the overall evidence of benefit on intermittent fasting is somewhat mixed. Clinical research shows that it seems to improve weight loss in people with obesity – various forms of intermittent fasting, usually combined with calorie restriction on non-fasting days, can reduce weight by about 15% in these patients. But it’s not clear if it benefits those who aren’t overweight. And it’s important to note that it doesn’t seem to work any better than maintaining a continuous calorie-restrictive diet.

If patients want to give it a try, there aren’t major safety concerns as long as nutritional needs are met when eating. For example, encourage patients to avoid highly processed foods and focus on consuming nutrient-dense whole foods whenever possible. And while it might not benefit weight loss for all patients, some people might find that it works well for their schedule and lifestyle, making it a more sustainable approach to weight loss. Also emphasize that intermittent fasting is very different from prolonged, water-only fasting. This should only be done under strict medical supervision.

Check out our recently updated monograph for more information.