Intermittent Fasting: Prescribed Nutritional Intervention

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Angela K. Fitch, MD, FACP, FOMA, associate director of the Massachusetts General Hospital Weight Center, has developed a shared decision-making protocol to support physicians in implementing intermittent fasting as a prescribed nutritional intervention.

"Physicians have historically shied away from prescriptive nutritional interventions," says Dr. Fitch. "We owe it to our patients to help them understand their benefits and make the necessary changes. Nutritional interventions should be approached in a shared decision-making context, just as we would do with other treatment options."

Dr. Fitch is pairing the introduction of intermittent fasting care protocols with the initiation of a collaborative study with Kathleen E. Corey, MD, MPH, MMSc, director of the Fatty Liver Center. The study will provide a controlled environment within which fasting-related reductions in liver fat levels can be monitored.

Initiating Nutritional Interventions Presents Challenges

"Historically, physicians regarded nutrition as an environmental factor. People grew things in their fields or backyards and ate them. Even though patients now have more choice and influence over their diets, the physician approach has not substantially changed," says Dr. Fitch. Physicians report several barriers to nutrition-based interventions. Such interventions often involve a time-intensive counseling approach.

In addition, evidence from nutritional studies, though widely available, is often conflicting—which can frustrate conversations with patients.

"Nutritional studies are fraught with challenges," says Dr. Fitch. Study reliability is impacted by a lack of unbiased funding, the timeframe needed to provide results and the operational challenges of controlling subjects' diets. So despite the evolution of diet as a lifestyle choice, physicians are unlikely to address nutritional issues with their patients, including those whose chronic conditions would greatly benefit from dietary interventions.

Dr. Fitch plans to change that. "Intermittent fasting programs can be successful if introduced in a supportive, shared-decision environment," Dr. Fitch says. "We aim to provide structure and support, enabling physicians to educate, provide concrete advice and help the patient break down barriers."

Studies Demonstrate Metabolic Benefits of Intermittent Fasting

Intermittent fasting uses one of several schedules which alternate eating and fasting periods, including:

• Time-restricted eating: Consuming meals in an eight to 12-hour period followed by 12 to 16 hours of fasting
• 24 hour: Alternating between one day of eating normally and one day of fasting for 24 hours
• 5:2 schedule: Eating normally five days a week, followed by two days of consuming fewer than 600 calories

Intermittent fasting triggers a metabolic shift from liver-derived glucose energy to adipose-derived ketone bodies. The metabolic shift elicits cellular reactions that strengthen the body's stress response, with potential clinical applications for obesity, diabetes mellitus, cardiovascular disease and other conditions.

In addition, the ketone bodies released during fasting periods provide benefits including stimulation of cellular maintenance and repair, increased stress resistance and mitochondrial biogenesis. One specific application is regulation of fat in the liver, the focus of an upcoming study by Drs. Fitch and Corey.

A Protocol-based Approach to Structuring the Intermittent Fasting Intervention

Intermittent fasting interventions are agnostic to food-specific dietary advice, allowing physicians and patients a simpler path to implementation. "Protocols provide structure and support to a physician team who must influence patient mindset shifts to successfully implement a prescriptive nutritional intervention," says Dr. Fitch.

Generally, the physician team will:

• Identify candidate patients: Fasting is not indicated for patients with eating disorders or those who are pregnant. Some conditions, like diabetes, necessitate clinical monitoring
• Educate patients: Physicians must provide easy-to-understand information on the benefits and effects of intermittent fasting followed by clear clinical recommendations
• Engage patient in shared decision-making: It's critical to discuss the patient's health, family and other goals, show the connection between fasting and goals and allow patient response and questions
• Develop a stepwise plan: Physicians should consider starting with a partial or less-daunting version of intermittent fasting. Identifying barriers and engaging patients in developing solutions bolsters success
• Provide support: Physicians should identify patient-individualized methods such as phone calls, social media and support groups to provide reminders and motivation
• Monitor patient: Establishing telehealth as a convenient appointment format eases the burden of monitoring

Upcoming Clinical Study to Improve Measurement of Fasting's Impact on Liver

Drs. Fitch and Corey will soon begin a time-restricted fasting study focused on patients with fatty liver disease. This condition is readily measurable and tends to respond to interventions very quickly. In addition, it provides results that can be generalized to other metabolic disorders.

"Our understanding of the benefits and risks of intermittent fasting is in its infancy," says Dr. Fitch. "Our upcoming controlled studies will help advance our understanding of the impacts of fasting and the effectiveness of prescriptive nutritional intervention protocols."

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