Share on Pinterest Experts say the quality of the calories you consume is the most important part of a diet. Oscar Wong/Getty Images
- Researchers at Johns Hopkins University in Maryland report that time-restricted eating and calorie counting lead to similar weight loss results.
- The study suggests that time-restricted eating naturally results in a reduction of about 200 to 550 calories per day.
- Experts say this diet may work well for some people, but the quality and quantity of what you eat is still most important.
The weight loss results of time-restricted eating are nearly identical to those of traditional calorie counting, according to a study from Johns Hopkins University in Maryland, published today in the journal Annals of Internal Medicine.
Time-restricted eating is a diet method that determines the hours of the day a person consumes calories each day. Popular fasting schedules, also known as intermittent fasting, include 16:8 (fasting for 16 hours, eating in an 8-hour window), or fasting for 24 hours once a week while following a relaxed eating schedule the rest of the week.
Specific calorie counting is generally not part of time-restricted eating.
Previous research and proponents of time-restricted eating have stated that this diet improves longevity, encourages weight loss through nutritional ketosis, reduces the risk of several diseases and improves cognition.
In their randomized controlled trial, researchers looked at 41 adults with obesity and prediabetes.
They randomly assigned participants to follow a fasting schedule or count calories. Both groups were given identical prepared meals with specific instructions about when to eat.
Participants assigned to a time restriction followed a 2:10 p.m. fasting schedule: they fasted for 14 hours and ate between 8 a.m. and 6 p.m. They consumed the most calories before 1 p.m
Participants assigned to general calorie counting ate between 8 a.m. and midnight and consumed the most calories in the evening.
After three months, participants in both groups were assessed for weight loss and changes in fasting glucose levels, waist circumference, blood pressure and lipid levels.
Researchers concluded that the results between the two groups were essentially the same.
"The study's findings that the health benefits of intermittent fasting are due solely to calorie restriction fully support my own view," Dr. Julie Manasseh, an obesity medicine specialist at Weight Journey: Medical Weight Loss, who was not involved in the study. , told Medical news today.
Although she supports intermittent fasting as a weight loss method, Manasseh says the benefits shown in research are a result of the weight loss itself, and not the fasting. Other experts agree with her assessment.
"It's hard to say whether I completely agree with the conclusion of this recent study or not," explains Shetal Desai Rautela, a registered dietitian and owner of Diabetes & Lifestyle Care.
Rautela, who was not involved in the study, suggested caution before committing to any diet or nutritional study.
"As a nutrition professional, it is extremely important to stay abreast of recent research," says Rautela Medical news today. "The American Heart Association (AHA) recently published the results of a... study with 20,000 participants showing that early time-restricted feeding, that common 16:8 schedule, was directly linked to a 91 percent increased risk of cardiovascular disease."
Some experts criticized the AHA's report. Furthermore, another recent study published in 2023 by the Endocrine Society concluded almost the opposite: it stated that a 16:8 fasting schedule improved glucose levels and cardiometabolic health.
"Overall, it's about what helps someone lose weight safely," says Rautela, who suggests that those considering fasting should first have a thoughtful conversation with their healthcare provider.
"Intermittent fasting can be difficult to maintain day in and day out, both physiologically and practically," says Rautela.
"Any form of calorie restriction will always yield first results for someone trying to lose weight," says Rautela. "The higher the weight loss goal, the faster the initial weight loss will appear on the scale. But is it sustainable?"
"For some people, it's probably not worth it if a diet is too forced, restrictive and difficult to maintain," Rautela warned, adding that it can still improve your relationship with your body's natural hunger cues.
"I always let my clients know that there is no quick fix for weight loss," Rautela explains, adding that she often dispels myths about intermittent fasting.
"Intermittent fasting isn't just about when you eat," she explained. "It still matters how and what you eat. The quality and quantity of your calories matter, even when you're fasting."
Rautela noted that there is a big difference in processing the calories of a Big Mac compared to a balanced meal consisting of fresh, whole foods.
Manasseh suggested three basic approaches to reducing your calorie intake: consuming lower-calorie foods with more fiber, eating smaller portions at meals, and eating less often - including intermittent fasting.
"You can use one, two or all of these methods to achieve calorie restriction," she said.
Like Rautela, Manasseh warns against very restrictive diets.
"Highly restrictive diets - which have been the mainstay of the diet industry - often involve excluding entire food groups," she said. "Diets like 5:2, which require people to fast two full days a week, are unsustainable in the long term."
Hunger signals and ideal eating patterns also vary from person to person.
"I have patients who never eat breakfast because they just aren't hungry first thing in the morning," Manasseh explains. "For these patients, I advise them not to eat breakfast and to eat lunch and dinner only when they are hungry. These patients follow a fasting schedule, but that suits them because it matches the pattern of their internal hunger signals."
"Culturally, we are constantly surrounded by food," says Rautela, adding that following a fasting schedule has helped some of her clients relearn how to recognize true hunger signals.
Rautela said she tries to embrace her clients' enthusiasm for any nutritional or weight loss approach.
"If they're eager to try something, it shows that they care about their health and want to explore it further," she explained. "My job is to build their knowledge base so they can make the right and safe decision with the support of their care team."
Like Rautel, Manasseh said mindless eating when you're not actually hungry is a constant challenge that fasting can help address.
"Emotional eating and stress eating, or excessive alcohol consumption, are also major factors for the majority of my patients," says Manasseh. "This needs to be addressed."
Manasseh and Rautela both emphasized the importance of helping each individual develop an approach to nutrition that suits their goals, habits, lifestyle and personality.
"I start with the patient's regular diet and help them make improvements to reduce calories while ensuring it is sustainable in the long term," said Manasseh. "Providing regular support and accountability during progress visits is critical to their success."
"Over the years I have moved away from a one-size-fits-all approach," says Rautela. "I have seen the most weight loss success with clients when we have regular check-ins to process challenges and behaviors while identifying their progress."
Of course, losing weight is only step one. Maintaining it comes next.
"The door never closes when it comes to maintaining your weight loss," says Rautela. "But that's a completely different story."
