Metabolic syndrome is a constellation of conditions that includes high blood pressure, high blood glucose, excess abdominal fat, and abnormal cholesterol levels. People with metabolic syndrome are at higher risk for developing heart disease, stroke, and type 2 diabetes. Findings from a new study suggest that fasting “jump starts” dietary strategies to improve symptoms of metabolic syndrome.

The “Western diet,” also known as the Standard American Diet, is rich in processed foods, red meat, high-fat dairy products, and added sugars. It plays contributing roles in the development of metabolic syndrome. Conversely, the DASH diet – Dietary Approaches to Stop Hypertension – is rich in fruits, vegetables, whole grains, nuts, legumes, low-fat dairy products, and dietary fiber, and low in red meat and sugar-sweetened beverages. It is one of the most commonly prescribed and successful dietary patterns for managing high blood pressure and other aspects of metabolic syndrome.

Gut health also plays a role in development of metabolic syndrome. In fact, an imbalance in the number of harmful versus helpful microbes in the gut, a condition known as dysbiosis, drives many disease states. Fasting and caloric restriction induce changes in the gut microbiota to promote health.

The three-month intervention study included 71 adults between the ages of 50 and 70 years who had high blood pressure and metabolic syndrome. Half of the participants followed a modified DASH diet alone, while the other half followed a combined fasting and modified DASH diet. The modified DASH diet was a plant-based dietary program that was low in sodium, fat, and sugar. The combined fasting/DASH diet started with two calorie-restricted vegan days (no more than 1,200 calories per day), followed by a five-day liquid fast that included vegetable juices and vegetable broth (300 to 500 calories per day). Upon completion of the fast, the participants followed the modified DASH plan. Both groups received approximately 50 hours of nutrition counseling, cooking lessons, and lifestyle coaching on exercise and stress management.

The authors of the study measured the participants' blood pressure and other markers of metabolic health, including body weight. They also measured immune cells and assessed the microbial makeup of the participants' gut microbiota.

Blood pressure (and the need for blood pressure medications) and bodyweight decreased among the participants following the fasting/DASH diet. The gut microbial composition of the participants following the fasting/DASH diet changed markedly during fasting, adopting a profile that was rich in microbes involved in short-chain fatty acid production, mucin degradation, and nutrient utilization. These changes in microbial composition reverted partially upon completion of the three-month DASH diet. The fasting/DASH diet also induced changes in immune cell populations, which were reversed when the participants ended their fast. Notably, fasting reduced the number of proinflammatory immune cells, whereas regulatory T cells increased. The participants who followed the DASH diet alone did not experience changes in their gut microbiota or immune cell populations.

These findings suggest that combining periodic fasting with a modified DASH diet improves blood pressure, body weight, and metabolic health in adults with metabolic syndrome better than the DASH diet alone. The participants in this study were of Caucasian-European background, potentially limiting the application of its findings. Further study is needed in a more heterogenous population.

• Link to full study.

• Learn more about fasting in this episode featuring Dr. Rhonda Patrick.