People with risk factors that increase their chances of having a heart attack, stroke, or type 2 diabetes may be able to lower their risk with a form of intermittent fasting known as time-restricted eating.
The findings suggest that time-restricted eating is a feasible and effective way to improve multiple aspects of cardiometabolic health, especially blood sugar and cholesterol control, even when people are already taking medications, says the lead author, Emily Manoogian, PhD, a postdoctoral fellow researcher. and researcher at the Salk Institute at UC San Diego School of Medicine.
"Although this study was conducted in adults with metabolic syndrome, based on these and other findings it may also help improve prediabetes, high blood pressure, high cholesterol or increased weight, and likely many more health problems," says Dr. Manoogian.
The subjects had an eating window of 8 to 10 hours
For the study, researchers randomly placed a total of 108 adults with metabolic syndrome into the time-restricted eating group or into a control group. The group consisted of 51 percent women with an average age of 59 years. The average weight was 196 pounds and the average BMI was about 31.
Unlike most studies of time-restricted eating, this study included people taking medications for metabolic syndrome, such as cholesterol-lowering or blood pressure-lowering medications.
Although both groups received nutritional advice on the Mediterranean diet, the intervention did not restrict what or how much people ate, and did not track physical activity. All participants recorded their meals using a mobile app.
The study participants tailored their time-restricted eating windows to their individual eating habits, sleep/wake times and personal commitments. The resulting eating schedule had each participant shorten their eating window by about 4 hours to a consistent 8 to 10 hours per day, starting at least an hour after they woke up and ending at least three hours before they went to sleep.
The personalized approach made it easier for participants to complete the intervention, compared to other intermittent fasting studies, which typically assign the same strict time window to all participants, Manoogian says.
After three months, people in the time-restricted eating group showed improvements in key markers of cardiometabolic health, including blood sugar levels and LDL cholesterol (bad cholesterol that can clog arteries), as well as lower levels of hemoglobin A1C, a marker of long-term diabetes. cholesterol. control of blood sugar levels over time.
The time-restricted eating group experienced a reduction in hemoglobin A1C (HbA1C) levels, from 5.87 to 5.75 percent, compared to a change from 5.86 to 5.84 percent in the standard counseling group.
People who followed time-restricted eating lost more weight
Those on time-restricted eating also lost an average of about 6.5 pounds (about 3 percent of their body weight), compared to about 3.5 pounds in the control group. According to the food diaries the participants kept over the 12 weeks, those who reduced their eating window ate about 350 fewer calories per day.
Time-restricted eaters also reduced their belly fat, and overall they did not experience significant loss of lean muscle mass.
"It was exciting to see that one lifestyle intervention could improve multiple components of metabolic syndrome. Usually treatments only affect one aspect of it," says Manoogian.
Time-restricted eating can be a 'stealth' way to improve your eating habits
These findings suggest that you can achieve additional (albeit modest) metabolic improvements through time-restricted eating without consciously cutting calories or losing a significant amount of weight, says Adam Collins, PhD, associate professor of nutrition at the University of Surrey in England, who was not involved in the research.
"The selling point of time-restricted eating is that you're not instructing people to limit overall intake or food choice, you're just limiting the eating window," says Dr. Collins.
This study shows that this window can be personalized to fit a person's typical eating and sleeping patterns, which can help the body metabolize meals and how they use and store carbohydrates and fat, he says.
Typically, in timed eating trials, people change their eating habits (even outside the time window) and end up eating slightly less, possibly by skipping a meal, avoiding snacks or being more mindful of their eating, Collins says.
It often causes people to eat less, healthier, or both by "stealth," he adds.
Time-bound May 'Use the body's natural wisdom'
Researchers believe that matching food intake to the body's natural circadian rhythm can improve the way the body metabolizes calories.
"Time-restricted eating re-engages the body's natural wisdom and utilizes daily rhythms to restore metabolism and improve health," said Dr. Panda.
It may be easier to change when you eat rather than what you eat
While the standard recommendation to "eat less and exercise more" sounds simple enough, the authors say it can be difficult to maintain.
The same goes for many fad diets, says Marilyn Tan, MD, an associate professor of medicine and endocrinologist at Stanford Health Care in California, who was not involved in the study.
"Extremely low-carb diets, the keto diet, and other restrictive diets can lead to meaningful weight loss and metabolic improvements in the short term, but many patients find it difficult to maintain them long term. The key to success is finding a diet change that you can maintain indefinitely," says Dr. Tan.
People often find it easier to follow time-restricted eating than very specific macronutrient profiles, she says.
"This study showed benefits after three months, and in a longer-term study the benefits could be even more remarkable," says Tan.
"Patients appreciate that they do not have to change What they just eat when they eat," says Manoogian.
Some people should consult their doctor before trying time-restricted eating
As long as healthcare professionals are aware of the diet plan, there is little risk to intermittent fasting per se, says Tan.
"If patients are taking insulin or medications that can cause low glucose levels, it is important that they discuss time-restricted eating with their healthcare providers," she says.
