A Pesco-Mediterranean Diet With Intermittent Fasting

JACC Review Topic of the Week

James H. O'Keefe, MD; Noel Torres-Acosta, MD; Evan L. O'Keefe, MD; Ibrahim M. Saeed, MD; Carl J. Lavie, MD; Sarah E. Smith, PHD; Emilio Ros, MD, PHD


J Am Coll Cardiol. 2020;76(12):1484-1493. 

In This Article

Intermittent Fasting/Time-restricted Eating

Unlike modern humans, our ancient ancestors did not have access to an unlimited supply of food throughout the year. Nor did they routinely eat 3 large meals plus snacks on a daily basis. Instead, they were typically engaged in a daily struggle to hunt and gather food, often in harsh milieus with sparse resources and seasonal scarcity.[10] These environmental challenges were the grist for the evolutionary mill, whereby Homo sapiens became genetically adapted to respond to intermittent fasting by becoming more resistant to stress.[51]

Time-restricted eating, 1 type of intermittent fasting, is the practice of limiting the daily intake of calories to a window of time usually between 6 to 12 h each day. Intermittent fasting when done on a regular basis has been shown to decrease intra-abdominal adipose tissue and reduce free-radical production.[51,52] This ancient evolutionarily conserved adaptation also elicits powerful cellular responses that improve glucose metabolism and reduce systemic inflammation, and may also reduce risks of diabetes, CVD, cancer, and neurodegenerative diseases.[52]

After a 12-h overnight fast, insulin levels are typically low, and glycogen stores have been depleted. In this fasted state, the body starts mobilizing fatty acids from adipose cells to burn as metabolic fuel instead of glucose. This improves insulin sensitivity. Time restricted eating is not more effective for weight loss than standard calorie-restriction diets, but it does appear to enhance cardiovascular health even in nonobese people.[53,54] Fasting may also lower blood pressure and resting heart rate, and improve autonomic balance with augmented heart-rate variability.[53–55] However, the evidence regarding time restricted eating remains preliminary, mostly based on animal models and observational human studies. The most popular form of time-restricted eating involves eating 2 rather than 3 meals and compressing the calorie-consumption window. No head-to-head studies have been performed to assess the optimal time window, but a 16:8 fasting to eating ratio is the most popular.[56]