Intermittent Fasting vs. Calorie Counting: Which Is More Effective for Weight Loss?

Fact checked by Nick Blackmer

• When compared, time-restricted eating (also known as intermittent fasting) and calorie counting result in similar weight loss, new research shows.

• The success of the two weight loss strategies may come down to one common thread: fewer calories consumed throughout a 24-hour period.

• Ultimately, experts say the best strategy for weight loss is the program that is most sustainable for the specific person.

New research comparing time-restricted eating (also known as TRE, intermittent fasting, or IF) to calorie counting shows that the two weight loss strategies produce similar results in a racially diverse population of adults with obesity.

Since intermittent fasting gained attention a couple of years ago as a way to lose weight, experts and dieters alike have debated whether this strategy is more or less effective than simple calorie counting. Some have argued that restricting eating to specific windows of the day naturally leads to successful weight loss, while others believe monitoring daily calories is a more effective path.

As it turns out, one might not be better at the job than the other.

While previous studies have examined the effects of combining calorie counting with intermittent fasting, this new research—published June 27 in Annals of Internal Medicine—is one of the first to look at these strategies in isolation.

Given that intermittent fasting is often simpler and easier for dieters than tracking every calorie in every bite throughout the day, the researchers wanted to see if it was also more effective, said Shuhao Lin, MS, RDN, the study’s primary researcher and a registered dietician with the University of Illinois Chicago.

If you’re weighing the merits of intermittent fasting vs. calorie counting for weight loss, here’s what to know.

How Researchers Compared the Two Weight Loss Strategies

For the study, Lin and her colleagues at the University of Illinois Chicago recruited 90 adults with obesity. Participants had an average age of 40; 33% were Black, and 46% were Hispanic.

The researchers divided the participants into three groups: one could eat only between noon and 8:00 PM, one restricted their regular daily caloric intake by 25%, and another made no dietary changes. Seventy-seven participants ended up completing the study.

After 12 months, the intermittent fasters and the calorie counters had surprisingly similar weight loss results. “In our study, we found that by shortening the eating window to eight hours, people reduced the same amount of calories intake as counting calories—around 400 kcal per day in both groups,” Lin said.

Both groups lost about 5% of their body weight.

Although intermittent fasting and calorie counting achieved neck-and-neck weight loss results, the same wasn’t true for another facet of health: blood sugar management. People in the 8-hour time-restricted eating group had improved insulin sensitivity, meaning their bodies got better at regulating blood sugar.

However, Lin said this may be because people in this group started with worse insulin sensitivity than participants in other groups, allowing more room for improvement. “Nonetheless, it shows the potential of time-restricted eating to improve insulin sensitivity in adults with impaired insulin sensitivity at baseline,” she said. “More research is needed to investigate how time-restricted eating may help people with impaired insulin sensitivity and type 2 diabetes.”

It’s important to note that the study’s results regarding weight loss may not apply when comparing the two approaches for a longer stretch of time. A study published in January 2023 in the Journal of the American Heart Association found that after six years, participants who restricted calories lost more weight than those who continued an intermittent fasting diet. Intermittent fasters who consumed medium- or large-sized meals during their daily window of eating were especially likely to gain weight over time.

Related: Could Calorie Restriction Slow Aging? New Research Shows a Link—But Experts Have Concerns

Why Intermittent Fasting and Calorie Counting May Be Comparable

“All diets work” has become a rallying cry among many weight loss specialists who believe that sticking to any energy reduction plan will likely help with weight loss. But intermittent fasting and calorie counting are quite different processes, so how do they achieve similar results?

“Since IF is shortening your eating window, you’ll likely consume fewer calories during that window by default,” Melissa Mitri, MS, RDN, weight loss expert and owner of Melissa Mitri Nutrition, told Health. “Additionally, IF can prevent late-night snacking and reduces your appetite throughout the day.”

Certain practices can make intermittent fasting and calorie counting more successful. “For IF to be effective for weight loss, you want to focus on the overall quality of your diet. Even though there are technically no ‘rules’ on what you can or can’t eat on IF, prioritizing nutritious whole foods lower in calories and fat will bring the best results,” Mitri said.

As for calorie counting, it can help to remember that not all calories are created equal. Some, such as those from complex carbohydrates and fiber, will likely provide more satiety, keeping you fuller throughout the day.

Choosing a Weight Loss Plan That Works for You

Choosing a diet for weight loss is a highly personal decision. If you’re choosing between intermittent fasting and calorie counting, you may want to assess your personal preferences, habits, and tendencies.

“If you don’t enjoy counting calories and using a food log app, then IF may be better for you,” Mitri said. “However, if your schedule doesn’t allow you to shorten your eating window easily, or you find yourself hungry when you go too long without eating, then calorie counting may be a better option.”

Regardless of which diet you opt for, don’t forget that weight loss alone isn’t an indicator that an eating plan is healthy and nutritious. “Whether you choose IF or calorie reduction for weight loss, it’s always important to prioritize a balanced diet,” Mitri said. Exercise will also offer enormous health benefits and burn additional calories, inching you toward your weight loss goal.

Related: What Is a Calorie Deficit—And How Do You Reach It?

Lingering Questions About Intermittent Fasting

Research into the effectiveness of intermittent fasting vs. calorie restriction is in the early stages, and future studies may reveal more about the advantages and disadvantages of the weight loss strategies. A larger study, for example, may help tease apart the merits of the two diets.

Lin said there are many additional research avenues to tackle regarding intermittent fasting specifically.

“I think the important next steps to research in this field is to expand the population we are studying,” she said. “For example, we need more research to see if time-restricted eating is safe and effective for people with type 2 diabetes, cancers, or other metabolic diseases."

"It would also be interesting to see research using intermittent fasting alongside other weight loss treatments, such as drug treatments, to improve or maintain weight loss," she added. "There are definitely many things we still have to explore in the field.”

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Read the original article on Health.