Aim to lower cardiometabolic disease risk when considering dietary pattern for obesity

Issue: July 2024

ByMichael Monostra

Fact checked byRichard Smith

Key takeaways:

Data show time-restricted eating does not confer clinically significant cardiometabolic benefits.
Switching to a Mediterranean diet may help lower one’s risk of developing diabetes.

PHILADELPHIA — Some dietary change may improve cardiometabolic measures beyond weight loss and providers should create a diet that will most benefit each individual with obesity, according to a speaker.

Weight loss can help reduce the risk for many complications, including cardiovascular disease, diabetes, atherogenic dyslipidemia and metabolic-dysfunction associated steatotic liver disease, according to Samuel Klein, MD, chief of the division of nutritional science and obesity medicine and the William H. Danforth Professor of Medicine and Nutritional Science at Washington University School of Medicine in St. Louis. He discussed data surrounding the timing of eating and types of diets that may be best for improving overall health.

“It’s not just getting people to lose weight, but really making them healthier,” Klein said during a presentation at the Heart in Diabetes CME Conference. “We really want to have a diet that will have people lose weight that will translate into benefits in all of these complications.”

Reducing portion size is one dietary change people with obesity can make to lose weight. Klein discussed how a person’s food intake increases as portion size increases. He said cutting portion sizes and avoiding ultraprocessed foods can be beneficial.

“Companies have learned how to make us like and want to buy processed foods,” Klein said. “They know that you can’t just eat one chip, and they know how to make food tasty and make you want to eat more. ... So just eliminating ultraprocessed foods may help people reduce their calorie intake.”

Limited benefits with time-restricted eating

Most Americans have eating periods that stretch for the majority of the day, according to Klein. He said more than 90% of Americans eat more than three times per day, the median daily eating period in the U.S. is about 14 hours and the percentage of Americans with a daily eating period of less than 12 hours is 10% to 15%. Additionally, eating a 240 kcal snack every day is tied to an increase in 24 lb over 3 years.

Alternate-day fasting and time-restricted eating are two dietary interventions that alter the amount of time a person eats in a given day. Klein said both approaches have shown minimal cardiometabolic benefits so far. A study published in JAMA Internal Medicine in 2017 found adults participating in alternate-day fasting had similar weight loss and cardiometabolic improvements as adults on a calorie-restriction diet.

Benefits are also limited for adults participating in time-restricted eating. A review of time-restricted eating trials published in Physiological Reviews in 2022 found no cardiometabolic benefits for adults engaging in 12-hour time-restricting eating. The only change observed with 8-hour time-restricted eating window was a body weight decrease of 0% to 4%. A 4- to 6-hour time-restricted eating window was associated with about a 3% decrease in body weight as well as a decline in fasting insulin. There were some variable changes with insulin resistance and blood pressure with a 4- to 6-hour time-restricted eating diet.

“There’s not very good evidence to date that time-restricted eating has clinical benefits in people,” Klein said. “That doesn’t mean future studies may not show a different result.”

Klein said most time-restricted eating trials have been short in duration and longer-term studies are needed to better assess cardiometabolic effects.

Mediterranean diet confers benefits

Changing the type of food one eats could have benefits for people with obesity, according to Klein. A meta-analysis published in The Lancet Diabetes & Endocrinology in 2015 found low-carbohydrate diets were associated with greater weight loss than low-fat diets. Klein noted the difference between the two dietary patterns was small and amounted to about 1 kg of body weight at 1 year. Two other trials found adults on a low-carb diet regained weight over time and had similar weight loss as adults eating a low-fat diet at 1 year. Klein said behavioral therapy along with a diet may be necessary to achieve long-term weight loss.

A low-carb diet could provide benefits beyond weight loss. A pair of studies showed reducing carbohydrate intake can improve glycemic control for people with type 2 diabetes. A Mediterranean diet focused on eating fruits, vegetables, legumes, fish, whole grains, nuts and olive oil could provide several cardiometabolic benefits. Findings from two studies showed adults eating a Mediterranean diet had a lower incidence of CVD and diabetes at 5 years than those eating a low-fat diet. Klein said some data have also shown a Mediterranean diet may reduce the risk for some cancers.

“The Mediterranean diet has significant benefits which we do not understand, because it doesn’t seem to change the general problem of lipids that are associated with CVD,” Klein said.

Regardless of diet, Klein said physical activity is crucial for any people who need to lose weight. A study published in Nature Metabolism in 2023 examined insulin sensitivity among adults with prediabetes who lost 10% of their body weight with diet only compared with diet plus physical activity. The physical activity plus diet group had a greater increase in insulin sensitivity than those who only lost weight with a diet.

“Physical activity is very important,” Klein said. “It’s often ignored in that it’s difficult to do, but we should all encourage patients who are on GLP-1 agonists, who lost weight through bariatric surgery, whatever the intervention is, to increase physical activity.”