Considering the Benefit of Intermittent Fasting for Heart Disease Risk

APRIL 13, 2019
Simon Murray, MD
Simon Murray, MDA presentation at the American College of Physicians (ACP) 2019 Internal Medicine Annual Meeting in Philadelphia, PA, this week focused on an interesting combination of burgeoning medicine and dietary regimen for the preventive care of atherosclerotic heart disease.

In a discussion focusing on the benefits of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, Pamela Taub, MD, associate professor of Medicine at the University of California San Diego, expressed her own professional interest in time-restricted feeding (TRF)—a form of diet wherein a person does not eat for a limited period of time. This is a form of fasting which has been practiced by many religious sects for centuries, and appears to be catching on as method of losing weight.

Beginning in 2017, Taub ran a small study to evaluate the effects of TRF on metabolic syndrome. She recruited patients for a study studying the effects of fasting for 12 hours each day as a treatment for metabolic syndrome. The evidence so far seems to be that intermittent fasting not only improves fasting glucose, lipids, and waist circumference, but also has the potential to reduce weight.

Taub enrolled 35 patients with the metabolic syndrome who were consuming calories for more than 14 hours a day, and had them reduce their period of eating to a 10-hour period (14 hours of not eating). The study ran for 12 weeks, and used fasting glucose levels as the primary end point.

Secondary endpoints were insulin, high-sensitivity C-reactive protein (hs-CRP), and triglyceride levels. Additional measurements were changes in body mass index (BMI) and blood pressure. Participants wore a continues glucose monitor and were monitored for compliance with a smart phone app, My Circadian Clock. (MCC) . This app is able to measure eating and sleeping patterns throughout the day. The final results of that study will be reported in June 2019.

In the US, 34% of the population have metabolic syndrome. Patient adherence is low with existing interventions known to work such, as calorie-restricted diets and exercise. Taub stated that the timing of calorie intake plays a role in metabolism. She believes that eating in a time frame that does not disrupt normal circadian rhythm, making it easier for patients to lose weight and improve metabolic parameters.

Erratic feeding by eating irregular meals disrupts normal metabolism making it difficult to make meaningful changes in eight and metabolic parameters. Studies in rodents have shown that TRF to an 8-12 hour period reversed the effects of diet designed to induce obesity. If this translates to humans, the diurnal regulation of metabolism through alternating fasting and eating might prove to be a promising treatment for metabolic syndrome.

A second trial began in September 2018, attempting  to measure changes in glucose hemostasis resulting from TRF by studying mitochondrial function and gene expression in skeletal muscle. It will assess biologic markers on metabolic function, and the impact on body composition.

The study designers hypothesized that 14 hours of TRF will reduce body fat, restore equilibrium between catabolic and anabolic processes, improve glucose hemostasis, and enhance mitochondrial function. Taub said that it appears that 14 hours of fasting every day will prove to be a very effective way to reduce cardiovascular risk in patients with metabolic syndrome, and by extension to the population at large.

Jason Fung, MD, a Canadian nephrologist, is regarded by many as a leading expert on intermittent fasting and low-carbohydrate diets, especially in treating patients with type 2 diabetes. He has written several books on the subject including the book, “The Complete Guide to Fasting.” 

His work mirrors what Taub is studying. His books are written for laypeople, but provide simple explanations on the rational for intermittent fasting and the various methods that patients can employ to use this therapy. Fasting is not only safe, but appears to be a highly effective treatment for metabolic diseases.

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