Study: Time-Restricted Eating May Improve Health of Adults with Metabolic Syndrome

It is estimated that more than one-third of adults in the United States have metabolic syndrome, a grouping of medical conditions that can lead to heart disease, diabetes and stroke. Risk factors attributing to the syndrome include elevated blood sugar, high blood pressure and high cholesterol.

In a recent collaborative clinical trial entitled TIMET, researchers from University of California San Diego School of Medicine and the Salk Institute found that a form of intermittent fasting, called time-restricted eating, could improve the health of participants diagnosed with metabolic syndrome and have prediabetes.

The study, published online in the Sept. 30, 2024 edition of Annals of Internal Medicine, demonstrated significant improvements in key markers of cardiometabolic health, including blood sugar and cholesterol and lower levels of hemoglobin A1c, a marker of long-term blood sugar management.

“Metabolic syndrome, especially when paired with prediabetes, represents a critical tipping point in which the risk for developing type 2 diabetes and heart disease is greatly increased,” said Pam Taub, MD, co-corresponding author of the study and professor of medicine at UC San Diego School of Medicine. “We’re hopeful the findings of this study can help others who are looking to address their metabolic syndrome and reduce their risk for type 2 diabetes.”

The TIMET study is the first to evaluate the benefits of a customized time-restricted eating schedule in patients taking medication for metabolic syndrome.

In the trial, 108 adult patients of UC San Diego Health with metabolic syndrome were randomized into either a time-restricted eating group or a control group. Both groups continued to receive standard-of-care treatments and underwent nutritional counseling on the Mediterranean diet. All participants logged their meals using the myCircadianClock mobile app, developed at the Salk Institute, which was then reviewed by trial researchers.

For the time-restricted eating group, protocols were customized to each participant’s eating habits, sleep/wake schedules and personal commitments. The resulting regimen had each person reduce their eating window to 10 hours per day, beginning at least one hour after waking up and ending at least three hours before going to sleep.

After three months, patients who had completed the time-restricted eating regimen showed significant improvements in key indicators of heart health. The reduction was similar in scale to what is typically achieved through more intensive interventions by the National Diabetes Prevention Program.

“Our bodies actually process sugars and fats very differently depending on the time of day,” said Satchidananda Panda, PhD, co-corresponding author of the study and professor at the Salk Institute. “In time-restricted eating, we are re-engaging the body’s natural wisdom and harnessing its daily circadian rhythms to restore metabolism and improve health.”

Circadian rhythms are the 24-hour cycles of biological processes that affect nearly every cell in the body. Erratic eating patterns can disrupt this system and induce symptoms of metabolic syndrome, including increased abdominal fat and abnormal cholesterol or triglycerides.

According to Panda, time-restricted eating (eating all calories within a consistent 10-hour window) allows individuals to eat in a manner that supports their circadian rhythms and their health.

Time-restricted eating was also associated with decreased body weight, body mass index (BMI), and abdominal trunk fat, a type of fat closely linked to metabolic disease. Importantly, participants did not experience any significant loss of lean muscle mass, which is often a concern with weight loss.

The TIMET trial adds to a growing body of evidence supporting the use of time-restricted eating as a practical, low-cost intervention to improve cardiometabolic health. The promising results suggest that health care providers could consider recommending this lifestyle intervention to patients with metabolic syndrome as a complement to existing treatments, though additional long-term studies are needed to determine whether time-restricted eating can sustain these benefits and ultimately reduce the risk of chronic disease.

“There is an urgent need for more effective treatment options that are accessible, affordable and sustainable for the average American,” said Taub, cardiologist and director of the Step Family Foundation Cardiovascular Rehabilitation and Wellness Center at UC San Diego Health. “Our research demonstrates that lifestyle interventions, such as time-restricted eating, can have a meaningful impact on the trajectory of a person’s overall health.”

The TIMET trial was funded, in part, by the National Institutes of Health (R01DK118278, R01CA258221, P30CA014195, UL1TR001442), the Robert Wood Johnson Foundation (76014), and the Larry L. Hillblom Foundation Postdoctoral Fellowship.

Additional co-authors of the study include Michael J. Wilkinson, Justina Nguyen, David Van, Ashley Rosander, Aryana Pazargadi, Jason G. Fleischer, and Shahrokh Golshan, UC San Diego; and Emily Manoogian, Monica O’Neal, Kyla Laing, and Nikko R. Gutierrez, the Salk Institute.

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