Which Is More Effective for Weight Loss and Fat Burning?

Intermittent fasting and calorie restriction are two common weight loss strategies. Both can help you limit the number of calories you’re consuming, and intermittent fasting could support fat burning. However, when it comes to weight loss, neither has a clear advantage.

Calorie restriction is one of the most basic methods of weight loss—when you eat fewer calories, your body burns stored fat for energy instead. People will often cut their normal caloric intake by around 500 calories (or 25-30% of their normal intake) when they’re following this eating plan.

With intermittent fasting, the focus is on eating time rather than calorie counting. This diet limits when you eat—either by shortening daily eating periods or instituting fasting on certain days—and it supports weight loss by naturally creating a calorie deficit.

Common intermittent fasting patterns include:

• Time-restricted eating: People eat within a set window of time while fasting for the remaining hours. Common plans include the 16:8 method—fasting for 16 hours, and eating during an 8-hour window—or the 12:12 method, where you eat between the hours of 8 a.m. and 8 p.m., for example.
• Alternate-day or periodic fasting: This involves alternating between lower-calorie “fast” days (often limiting your intake to around 500 calories or less) and days of regular food intake. Fasting days are usually nonconsecutive throughout the week. One popular method is called 5:2 intermittent fasting, which is five days of normal eating interspersed with two days of significant calorie restriction. People may also do a 4:3 fasting plan, where they eat normally for four days and fast on three nonconsecutive days each week.

Though intermittent fasting often leads to reduced calorie consumption and weight loss, it doesn’t always. Some people eat less because there are fewer opportunities to snack, while others may end up eating the same amount (or even more) during their restricted eating window.

Ultimately, to lose weight, people need to alter their diet so they’re in a calorie deficit, or burning more calories than they’re consuming. Restricting calories and eating less is one method to do that, and intermittent fasting is another.

Studies comparing intermittent fasting with daily calorie restriction generally find the two result in similar weight loss when total calorie intake is comparable.  

For example, a yearlong study looked at two groups of participants who restricted their caloric intake. One group was also asked to consume all their daily calories within an 8-hour window. In the end, both groups lost similar amounts of weight.

That being said, personal preferences and lifestyle do play a role in how much weight a person loses on a particular diet. Weight loss results from intermittent fasting or calorie restriction (or any other diet) can vary based on factors such as:

• Adherence: Some people find intermittent fasting easier to follow than monitoring daily calories, but others find it leads to overeating later.
• Daily intake: Research suggests that weight loss from intermittent fasting is caused by a calorie deficit, not necessarily by changes in eating time. Weight loss may be more or less effective depending on your daily caloric intake.
• Support: People are more successful with weight loss plans, including intermittent fasting and calorie restriction, if they have access to regular coaching and behavior change support.

Fat burning (also called fat oxidation) refers to the body’s ability to use fat for energy. Intermittent fasting can increase fat burning—that’s because during fasting periods, glucose (sugar from carbohydrates) isn’t readily available, so the body shifts to using fat stores for its fuel.

Some research suggests that spending more time fasting creates more opportunities for the body to burn fat.

However, fat burning and fat loss are not the same thing. Fat burning refers to how much fat your body is using for fuel at a given moment in time, whereas fat loss refers to a general reduction in stored body fat over time.

Though intermittent fasting may boost fat burning, sustained fat loss comes from being in a calorie deficit. Research shows that both calorie restriction and intermittent fasting lead to similar fat loss in the long term.

Adherence, or whether you maintain your weight-loss plan, is the most important predictor of weight-loss success. The most effective strategy is the one you will continue to follow for more than a week or two.

Work schedules, social plans, health history, your relationship with food, and other lifestyle factors all play a role in determining which approach is best for you. There are some pros and cons to both eating patterns:

• Intermittent fasting: The emphasis on timing instead of counting calories may be simpler to follow and require fewer dietary changes. But fixed eating windows may feel rigid or interfere with social events or family meals. Plus, some research suggests people following intermittent fasting plans feel hungrier than those doing calorie restriction.
• Calorie restriction: This plan offers more flexibility in meal timing; however, tracking calories may feel tedious or restrictive for some people.

If you’re not sure which plan might be best for you, here are a few things to consider:

• Think about which approach feels most realistic for your lifestyle and schedule, especially when it comes to your normal meal schedule.
• Aim for a sustainable calorie deficit rather than drastic weight loss.
• Prioritize protein, fiber, and physical activity regardless of method.
• Expect weight loss to take time and not happen overnight.