Time-restricted eating slashes weight and blood pressure in people with metabolic syndrome, finds study

06 Dec 2019 --- Limiting food consumption to a ten-hour window each day can lead to weight loss, lower blood pressure and more stable insulin levels. This is according to a pilot study from the University of California San Diego School of Medicine and the Salk Institute for Biological Studies, which found that time-restricted eating – a form of intermittent fasting – improved the health of participants who had been diagnosed with metabolic syndrome. By delaying the onset of diabetes even by one year in a million people with prediabetes, the intervention could potentially save roughly US$9.6 billion dollars in health care costs, according to a researcher of the study.

“Time-restricted eating is a simple dietary intervention to incorporate, and we found that participants were able to keep the eating schedule,” says Satchin Panda, co-corresponding author and Professor in Salk’s Regulatory Biology Laboratory. “Eating and drinking everything – except water – during a ten-hour window allows your body to rest and restore for 14 hours at night. Your body can also anticipate when you will eat, so it can prepare the body to optimize metabolism.”

While erratic eating patterns can disrupt the circadian rhythm and induce symptoms of metabolic syndrome, including increased abdominal fat and abnormal cholesterol or triglycerides, time-restricted eating lets people eat in a way that is easier on their bodies.

Pam Taub, co-corresponding author and Associate Professor of Medicine at UC San Diego School of Medicine and Cardiologist at the Cardiovascular Institute at UC San Diego Health. (Source: UC San Diego Health Sciences)The study involved 19 participants diagnosed with metabolic syndrome, which is a group of risk factors such as high blood pressure and cholesterol levels. The condition increases the risk for adverse health issues, from heart disease and diabetes to stroke.

Sixteen of the participants were taking at least one medication, like a statin. The subjects used an app to log when and what they ate during an initial two-week baseline period followed by three months of ten-hour time-restricted eating per day. They were told they had full control to plan mealtimes and how much to eat, as long as all food consumption occurred within a ten-hour window.

By the end of the 12-week study span, participants averaged a 3 percent reduction in weight and body mass index (BMI) and a 4 percent reduction in abdominal/visceral fat. Many people also had reductions in cholesterol and blood pressure, as well as improvements in fasting glucose. Notably, 70 percent of participants reported an increase in sleep satisfaction or in the amount they slept. 

“Patients also reported that generally, they had more energy, and some were able to have their medications lowered or stopped after participating in the study,” adds Pam Taub, co-corresponding author and Associate Professor of Medicine at UC San Diego School of Medicine and Cardiologist at the Cardiovascular Institute at UC San Diego Health.

Crucially, over two-thirds of the group continued to use time-restricted eating at least part of the time for up to a year after the study concluded. Taub further notes that it can be difficult to convince prediabetes or metabolic syndrome to make lasting and meaningful lifestyle changes. “There is a critical window for intervention with metabolic syndrome. Once people develop diabetes or are on multiple medications, such as insulin, it can be very hard to reverse the disease process.”

The researchers are currently conducting another clinical trial to examine the benefits of time-restricted eating in a larger group of more than 100 participants with metabolic syndrome. The study examines additional measures that will help the researchers investigate changes in body composition and muscle function.

Experts weigh in
Responses from other experts in the nutrition space have been largely positive. Alexandra Johnstone, Professor at the Rowett Institute at the University of Aberdeen, notes that the paper builds on the researchers’ previous mice studies. In these investigations, the positive health effects occurred even in the absence of changes in energy intake. Participants averaged a 3 percent reduction in weight by the end of the 12-week study.

“This is a small study, but critical in that it is the first step in translating what we know from experimental animal studies to be true in humans. It is encouraging that some participants continued for up to one year because compliance is always a challenge with any kind of diet or lifestyle modification. Importantly it enabled people to self select the eating window, rather than skipping meals,” adds Jenna Macciochi, Lecturer in Immunology at the University of Sussex.

She continues that a key point of the study is that the participants could self-select the eating window. “This is important because the previous studies that the authors cite in healthy individuals used a predetermined ten-hour eating window and the participants found this harder to stick to. Adherence is a big plus for this study since that is one of the hardest things about any kind of weight loss practice.”

However, Duane Mellor, Registered Dietitian and Senior Teaching Fellow at Aston Medical School, flags the study’s small, uncontrolled and non-randomized nature as a weakness. “It does provide some evidence, but as there is no control group or randomization, it is very hard to tell if people did better following time-restricted eating than if they had followed another type of diet.” 

A study earlier this year also highlighted the potential health benefits that can come from fasting from dawn to sunset for 30 days, noting that it could even offer a potential new treatment approach for obesity-related conditions. 

By Katherine Durrell