New research shows that people who try time-restricted eating can stay on that diet longer than those who count calories.
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New research shows that people who try time-restricted eating can stay on that diet longer than those who count calories.
Image of Elizabeth Fernandez/Getty
Intermittent fasting has gained popularity in recent years as an alternative to more traditional weight loss advice, including calorie counting, which can be cumbersome and difficult to maintain for some people. .
Intermittent fasting can take many different forms, one approach – known as time-restricted eating – that limits when people eat within a specific time frame, usually around six to eight hours .
Some study hint this may be success for short-term weight loss because people will eat less, but it’s still unclear how well it works over a longer period of time.
A study published Monday may have the answer.
“We really wanted to see if people could lose weight this way over a year? Can they maintain the weight loss?” speak Krista Varadyprofessor of nutrition at the University of Illinois, Chicago, who has studied intermittent fasting for the past two decades and led the new study.
Varady’s research found that intermittent fasting can actually help people lose weight and maintain it over the course of a year, with the same effect as tracking calories. The results of the clinical trial are published inside Chronicle of internal medicine.
The magnitude of the weight loss was negligible – equivalent to about 5% of body weight – but the findings are encouraging to researchers in the field, in part, because they highlight that people can maintain their habits. this habit for a long time.
“That’s pretty interesting,” said Courtney Peterson, a professor of nutrition at the University of Alabama at Birmingham, who was not involved in the study. “This study has the most convincing results showing that people can stick with it, that it’s not a fad in the sense that people can do it for three months and they’ll be fine. lose weight in a year.”
‘Natural calorie restriction’
Varady’s team recruited 90 obese adults (meaning a BMI over 30) from the Chicago area and randomly assigned them to three groups: one that ate only between noon and 8 p.m.; another person has to count calories and cut their daily energy intake by 25%; and the third group did not make any changes to their eating habits.
After six months of weight loss, the participants went through a “weight maintenance phase”. That was done by extending the eating time from 8 hours to 10 hours in the intermittent fasting group and increasing calorie intake in the calorie-restricted group.
Varady said they designed the study that way because “most people on a diet will lose weight for about six months and then the weight will stabilize.”
The study found that time-restricted eaters lost an average of about 10 pounds more than the control group, while those who counted their calories lost about 12 pounds. The difference between the two groups was not statistically significant.
“The bottom line is that you can basically achieve the same level of energy restriction by counting time instead of counting calories,” says Varady.
Before study about intermittent fasting found that when people restricted their food intake to an 8-hour period and intentionally restricted calories, they achieved the same weight loss over the course of a year as those who only restricted calories, but don’t limit eating for a specific time period.
What’s different in the new study is that those in the intermittent fasting group weren’t instructed to track their calories, but they ended up reducing their daily intake by about 400 calories — the same amount as the calorie counting group. .
The results suggest that time-restricted eating can lead to a sort of “natural calorie restriction,” Varady said. She says it could be largely a result of people having less time to eat, especially after dinner.
“People usually eat between 12 and 14 hours, so all we are doing is cutting back about 6 hours,” she said, “I think mostly we cut give up snacks after dinner.”
Peterson says that setting limits on when you eat can have an “anti-snack effect” that can prevent mindless nighttime eating. She says data from her lab also suggests that intermittent fasting can affect hormones and help regulate appetite.
The study did not find any meaningful differences in heart health and metabolism between the two weight loss groups. Research shows that eat earlier during the day can be beneficial for metabolic health, but Varady says they choose between noon and 8 p.m. because this reflects how people tend to eat time-restricted foods in the real world.
“From a feasibility perspective, I don’t know of anyone who would stop eating before 4pm every day,” she said. “If you can do it or if it fits your lifestyle, then definitely, go ahead.”
Support and advice can help you lose weight more sustainably
Another feature of the study was that both weight loss groups received regular consultations with nutritionists, during which they learned about “healthy food choices” and learned cognitive behavioral strategies to prevent weight loss. gain weight back.
This kind of “in-depth support” is important, say Dr. Adam Gilden. “Most of the people who are doing this are not doing it with any kind of dietary or behavioral support. They’re doing it themselves,” said Gilden, an associate professor of medicine at the University of Colorado and author of an editorial. published in addition to new research.
He says his patients often tell him they’re unsuccessful when they try time-restricted eating.
Gilden shows the result of other The trial showed that time-restricted eating did not lead to significant weight loss over the course of 12 weeks. In that study, he pointed out that there was no dietary counseling and support.
In the study, where participants received that support, “time-restricted eating was as effective as traditional calorie restriction,” he said. But he doubts that these techniques will yield the same results in the real world without assistance.
In the study, people who followed a time-restricted diet and counted calories were “moderately compliant” over the course of the year-long study.
But Peterson said previous research has shown that the work involved in counting calories – which tends to become standard advice for people when they are advised about weight loss – makes weight loss difficult. so difficult. People need to be educated about portion sizes and calories in different foods, and then track and record meals.
“It can be a huge pain for a lot of people,” she said.
This study comparing time-restricted eating with standard calorie counting shows that “with much less effort, you can cut your calories by the same amount,” says Peterson.
The implication of this study is not that intermittent fasting is somehow “an excuse to change your diet for the worse,” says Dorothy SearsProfessor of nutrition at Arizona State University’s College of Health Solutions and executive director of Community and Clinical Translational Sciences.
“We are designed to handle the nutrients of the day optimally,” says Sears. “So start by letting people eat during the day and avoid eating at night, which in itself is associated with negative health outcomes.”
There’s no need to “struggle” over whether calorie counting is better or worse, she said, “but we need to test whether time-restricted eating works, and this study is showing See, yes, it works.”
