- Research found that people lost the same amount of weight on an intermittent fasting diet as they did on a calorie-counting diet.
- People in both groups were able to keep the weight off after a year.
- Nutritionists say there are a few factors to consider when choosing one over the other.
Intermittent fasting has been a buzzy way to lose weight for years, with devotees swearing that eating during a certain window of time has helped them reach their goals and keep excess weight off. But new research has found fasting diets may not be any better than counting calories when it comes to weight loss.
The small study, which was published in the Annals of Internal Medicine, followed 77 people with obesity and randomly assigned them to one of three groups for six months. One group followed an intermittent fasting diet, where they only ate between the hours of noon and 8 p.m., another ate whatever they wanted but reduced their total calorie count by 25%, and the third didn’t change their eating habits.
After six months, the researchers switched things up slightly: They had the intermittent fasting group eat over a 10-hour window, and the group that counted calories ate enough food to feel satisfied. People in both dieting groups lost weight in the first six months, and maintained it after the initial six-month period, leading to a 5% reduction in body weight after a year.
After the year was over, the intermittent fasting group ate 425 fewer calories per day on average than the control group and lost about 10 more pounds. The group that counted calories had about 405 fewer calories a day than the control group and lost 12 more pounds.
“Time-restricted eating is more effective in producing weight loss when compared with control but not more effective than calorie restriction,” the researchers concluded.
“Despite the popularity of a time-restricted eating diet, there are only a few long-term studies on the effect of time-restricted eating for weight loss,” says lead study author Shuhao Lin, M.S., R.D., a Ph.D. candidate at the University of Illinois at Chicago. “Many previous studies combined time-restricted eating with calorie counting and compared that to calorie counting alone. However, the strength of time-restricted eating is that it is simple and people do not have to count calories. Therefore, we are interested in how time-restricted eating alone would compare to calorie counting in the long term.” Investigating the ability to maintain weight loss was also important, Lin says.
It’s important to note that both methods are restrictive, and might not be for everyone. Check with your healthcare provider prior to starting a new regimen to find out if it’s right for you.
But why might intermittent fasting and calorie counting have the same impact, and how can you know which is right for you if you’re looking to lose weight? Nutritionists explain.
Why might intermittent fasting and calorie counting give you similar results?
It’s important to note that this isn’t the first study to find that intermittent fasting and calorie counting lead to similar weight loss results. A study of 139 people with obesity published in The New England Journal of Medicine last year had one group limit their daily calories, while another had to limit their calories and eat within the hours of 8 a.m. and 4 p.m. The researchers found that people in both groups lost about 14 to 18 lbs, and those in the time-restricted group didn’t lose any more weight than those in the calorie-counting group.
But the latest study found that people lost similar amounts of weight as calorie counters on an intermittent fasting diet, even when they weren’t counting calories.
Experts say there may be a few reasons why both eating plans yield similar results. “One thing I’ve seen with clients who practice intermittent fasting is that it can make someone more mindful of what they are consuming within their eating window, similar to calorie counting,” says Jessica Cording, R.D., author of The Little Book of Game-Changers. “When someone is doing it in a way that’s constructive and supportive, it can make them more intentional in choosing nutrient-dense foods within their goals.”
Calorie counting also encourages people to think about food a lot, points out Albert Matheny, R.D., C.S.C.S., co-founder of SoHo Strength Lab and advisor to Promix Nutrition. “With intermittent fasting, you’re not focused on the little details. Everyone can tell time. You can think about other things during your day and not be so focused on food.” That may lead to someone taking in fewer calories by default, he says.
Is one “better” than the other?
Not necessarily. “When we talk about weight loss methods, it always depends on the people’s preferences,” Lin says. “Some people may find time-restricted eating easier and more effective than counting calories, while others may find it less effective.”
Cording agrees. “It’s really individual,” she says.
But Matheny points out that intermittent fasting is often easier for most people to follow. “If it’s a lot easier and you get the same results, great,” he says. “Simplicity in health and fitness is the number one thing for people. Worrying about portion control is hard.”
Intermittent fasting vs. calorie counting for weight loss
Experts say it’s important to look at your lifestyle and eating habits to see how each type of diet may fit into your life. “What we see in the studies is that people lose the same amount of weight on average in both groups,” Lin says. “However, there are lots of variations in how each person reacts to their diet.”
Cording suggests looking at past experiences you’ve had with weight loss efforts and thinking about what has and hasn’t worked for you. “That will give you clues on what may or may not work for you in the future,” she says. “If you’ve tried calorie counting in the past and it made you feel obsessive, it’s not a good approach for you. If you want the freedom to not count calories but want some sort of structure, intermittent fasting may be a good fit.”
Cording also recommends paying attention to when you tend to be the most and least hungry during your day—that can also tip you off to whether an intermittent fasting diet may be doable for you.
If you want to lose weight and you’re unsure of how to start, Lin recommends meeting with a registered dietitian. They can help you figure out your weight loss goals and how to meet them on a personalized level.
Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Self, Glamour, and more. She has a master’s degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.