How to Lose Body Fat: The Science-Backed Ways That Actually Work

Having a lot of body fat doesn't just make it harder to fit into your jeans. Too-high levels are tied to serious health risks like high blood pressure, diabetes, heart disease and even some types of cancer, per the American Heart Association. But what's the best way to bring your body fat levels down into the healthy range?

Exercise can boost your body's fat-burning abilities, but it's less important than what you eat. (Image: knape/iStock/GettyImages)

Trying to lose body fat can sometimes feel complicated. But the best tools for getting leaner happen to be fairly straightforward — and anyone can use them. Here's a look at why some of us end up with excess body fat, plus the most effective ways to lose it for good.

The Skinny on Body Fat

Before diving into the best ways to lose fat, it helps to understand a little bit about how we gain fat in the first place — and what our bodies do with it. Basically, fat storage happens when we consume more calories than our bodies need.

When we eat, our bodies release the hormone insulin. Insulin helps the body's cells absorb glucose — or blood sugar — and fatty acids from food to be used as energy, explains board-certified obesity medicine physician Jaime Harper, MD. Any extra calories that don't need to be used as energy get saved in our fat cells for later.

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Fat storage is an evolutionary mechanism that helped our ancestors survive in times of famine: When there wasn't much food around, the body could stay fueled by burning through its fat stores. We still burn fat the same way today whenever we use up more energy than we take in.

"When we haven't eaten in a few hours or begin to exercise, the body's hormonal state signals to fat cells to release some fat for energy," says Georgie Fear, RD, CSSD, author of Lean Habits for Lifelong Weight Loss.

Enzymes break down stored fat into fatty acids and other components, which are then released from the cell and taken up by other cells to burn for energy. Burning the fatty acids produces water and carbon dioxide, which exit the body through our urine, sweat and breath. Over time, that adds up to body fat — and pounds — lost.

Losing Weight vs. Losing Fat

When most people say that they want to lose weight, what they really mean is that they want to lose fat. The body's total weight is made up of water, muscle, bones and fat, Dr. Harper explains. Fat is the squishy stuff that sits beneath the surface of the skin and makes your jeans feel tight. It's also what ups the risk for serious health problems, especially if the fat accumulates around your internal organs.

The thing is, there are ways to lose weight that don't involve losing much actual fat. Sweating a lot, for instance, can cause you to lose several pounds of water weight.

"But it's just fluid weight. In that case, fat and weight loss aren't the same thing," says Anis Rehman, MD, associate program director of the Endocrine Fellowship at Southern Illinois University School of Medicine.

As soon as you consume the lost fluids, your weight will bounce right back up to its usual number. But in order to actually get leaner and improve your health, you need to lose body fat.

How Much Body Fat Is Healthy?

No two bodies are exactly alike, and everything from your age, to your hormones and genetics all play a role in how much body fat you have — and how easy or difficult it is to get leaner. Men also tend to have less body fat than women, and athletes generally have less body fat than non-athletes.

Here's a look at what's considered normal, according to the American Council on Exercise (ACE):

Body Fat Norms for Women

  • Acceptable: 25-31%
  • Fitness: 21-24%
  • Athletes: 14-20%
  • Essential: 10-13%

Body Fat Norms for Men

  • Acceptable: 18-24%
  • Fitness: 14-17%
  • Athletes: 6-13%
  • Essential: 2-5%

How to Lose Body Fat

Now that we've covered where body fat comes from and how much you should have, let's look at what you can do to get leaner. Losing body fat can be challenging, but the tools you can utilize to make it happen aren't all that complicated. In a nutshell? It all comes down to eating less and moving more.

"Lower calorie density diets, including high amounts of fruits and vegetables and less fat, have been shown to be equally effective for weight management and have fewer risks than low-carb diets."

Losing Fat Through Diet

The whole reason that fat exists is to serve as a backup source of energy for when food is scarce. So it makes sense that cutting your overall calorie intake is the most effective way to burn fat. "Diets of any composition can lead to fat loss, because your body will burn fat as long as you are consuming fewer calories than you're burning," Fear says.

How much should you cut your calories, exactly? Most experts recommend trying to eat 250 to 500 fewer calories per day. "That will enable you to lose 1/2 to 1 pound a week," says Fear.

It might be tempting to slash your intake by more than that, especially if you're trying to jumpstart your weight loss or want to see results fast. But the move could actually backfire. "It can induce compensatory changes in your body, such as burning fewer calories when you exercise, along with lower levels of thyroid and sex hormones," Fear says. Not to mention that extremely low-cal diets are hard to sustain, since they tend to leave most people feeling hungry and deprived.

The Best Fat-Burning Diet

Calories aside, what about the foods themselves — can certain types of diets help you lose more body fat than others? The keto diet, for instance, is often touted as the best way to lose weight, since cutting your carbs super low encourages the body to switch to burning fat for fuel.

And indeed, research has shown that low-carb diets are more effective for weight loss than low-fat diets — at least for the first six to 12 months, per a July 2019 review in StatPearls. "They can reduce how hungry you feel, which some people find as a helpful tool that enables them to eat less," Fear says.

But the fat-loss benefits are less clear beyond the one-year mark, according to the Mayo Clinic. And there could be other risks: A six-year study of 25,000 people published April 2019 in the European Heart Journal found that people who ate the lowest-carb diets had a 32 percent higher chance of dying from any cause compared to those who ate the most carbs.

In short? Low-carb diets might be helpful for losing fat at first, but it ultimately comes down to calories. "Lower calorie density diets, including high amounts of fruits and vegetables and less fat, have been shown to be equally effective for weight management and have fewer risks," Fear says. If you eat a little bit less overall, your body will turn to your fat stores to make up the difference — which will add up to body fat lost.

When you eat can have an affect too. "I recommend intermittent fasting to my patients, having them eat for eight hours and fast for 16 hours," Dr. Harper says.

Indeed, intermittent fasting has been shown to help with weight loss better than simply restricting calories throughout the day, according to a 50-week study of overweight and obese women published November 2018 in The American Journal of Clinical Nutrition. "In a fasting state, the body doesn't release the hormone insulin. Without insulin, the body doesn't store fat and instead breaks down fat you already have for energy," Dr. Harper explains.

"HIIT is very efficient. You can burn a lot of energy in a short amount of time — say, around 500 calories in a 45-minute session."

Losing Fat Through Exercise

Cutting your calorie intake is the quickest, most effective way to burn fat. But you can torch additional calories — and get more fat-burning bang for your buck — by adding in regular exercise. "Literature shows that a combo approach of diet and exercise is best," Dr. Rehman says.

Why? Cutting 500 calories from your diet is fairly doable. But burning that number of calories through exercise takes more work. "It takes less time to not eat a 100-calorie piece of toast than it does to burn 100 calories by running a 10-minute mile," explains Richard Wilcock, certified strength and conditioning specialist and owner of Flagship Fitness.

Indeed, research shows that physical activity alone isn't usually enough to encourage fat loss: A review of 80 studies published October 2007 in the Journal of the American Dietetic Association found that exercising alone — without diet changes — leads to minimal weight loss at best. And research done since then has backed up this position.

But exercise is a great way to support eating for fat loss — and it could help you reach your goal a little faster. "If we eat 1,800 calories a day and use 1,800 calories a day, then burn an additional 200 calories from exercise, the body will turn to stored fat for energy since there's no leftover glycogen stores from what we've eaten," Wilcock says.

So, what are the best fat-burning exercises? If you're looking to burn the most calories in the shortest amount of time, high-intensity interval training (HIIT) — like alternating jogging with sprinting — might be the way to go. "Fat loss is all about using more energy than you consume, so whichever exercise burns the most energy would be the best for fat loss," says Wilcock. "HIIT is very efficient. You can burn a lot of energy in a short amount of time — say, around 500 calories in a 45-minute session."

What's more, interval workouts could keep your body in a calorie-torching state even after you're done exercising. One study published February 2012 in the International Journal of Sport Nutrition and Exercise Metabolism found that subjects who completed sprint intervals continued burning fat for up to an hour after the sprints were over.

It's a good idea to add in regular strength-training sessions too. Weight training doesn't burn as many calories as interval workouts (30 minutes of strength training burns around 100 calories), but it'll help you preserve or even gain lean muscle mass. That's important, because the more muscle tissue you have, the higher your calorie burn will be (even when you're at rest!), according to the Mayo Clinic. And the more calories you're burning, the fewer excess calories will potentially end up being stored as fat.

Keep in mind, these exercises will help you burn fat all over your body. Despite the fact that you might want to get leaner in one specific area, that's not how fat loss works, say Dr. Rehman. Endless crunches won't burn away belly fat, and tons of squats won't burn fat around your thighs.

Another tip: If you can, consider working out first thing in the morning before eating breakfast. Because your body's glycogen levels are bottomed out from not eating since the night before, it'll turn to your stored fat for energy pretty quickly, which can boost your fat-burning overall.

In fact, one study published October 2019 in the Journal of Clinical Endocrinology and Metabolism found that subjects who exercised before breakfast burned double the amount of fat compared to those who worked out later in the day, after eating.

Fat Loss for Men vs. Women

There are lots of factors involved in how quickly (or slowly) a person is able to lose fat. But one of the biggest is sex. Men have higher levels of the hormone testosterone, which promotes the growth of lean muscle tissue and can make fat loss quicker and easier. One study published August 2018 in Diabetes, Obesity, and Metabolism found that when subjects ate the same low-calorie diet for eight weeks, male subjects lost an average of 26 pounds while female subjects lost an average of 22.

Sex also determines where your body is most likely to store much of its fat. "For men the main area is the stomach. For women, it's the breasts, bum and thighs," says Wilcock.

That's not to say that women can't lose body fat or reach their desired body fat percentage. But they might have to work a little bit harder.

The Cleveland Clinic recommends women do 30 minutes of resistance training at least twice a week to boost muscle mass. And of course, pay close attention to how many calories you're taking in. While everyone's calorie needs are a little different, women may need to eat between 1,200 and 1,800 calories daily to lose weight. But keep in mind that the right number depends on a wide variety of factors, including your age, current weight and activity level.

Measuring Fat Loss

When you're trying to lose fat, it helps to know where exactly you're starting from. While a typical bathroom scale can tell you how much you weigh, it's not the best tool for figuring out your body fat percentage or tracking your fat loss.

For that, you'll need body fat calipers. This handheld device is designed to measure the thickness of skin at the biceps, triceps, low shoulder blade and hip, which experts can use to calculate your body's percentage of fat. Since it's tough to take accurate skinfold measurements at home, your best bet is to have it done by a personal trainer or health practitioner.

Calipers aren't the only tool for measuring body fat, but they're widely considered to be the simplest and least expensive, per the ACE. The problem is, while calipers are fairly accurate, they're not foolproof.

If you're looking for a super precise measurement, consider getting a dual x-ray absorptiometry (DEXA) scan. These scans send small electrical currents through the body to give a super accurate analysis of a person's weight, body fat, muscle mass and water. "It's considered the gold standard in measuring body composition, but it is expensive, not convenient and it does give off a small dose of radiation," Dr. Harper says.

Don't have access to any fancy measuring equipment? Use LIVESTRONG.com's Body Fat Calculator to estimate your body fat percentage and track your progress as you lose weight.

Bottom Line: The Best Way to Burn Fat

Our bodies store fat when we take in more energy than we use up. So in order to lose fat, it simply comes down to reversing that process.

By using more calories than you take in, your body will burn fat from its fat stores to cover the rest of your energy needs. Eating a lower-calorie diet is the most effective way to make that happen — and while when you eat might play a role, the most important factor is what you eat. But you can get an extra boost by exercising regularly, especially with interval or strength-training workouts.

In a nutshell: "Usually, a low-calorie diet along with exercise results in fat loss," Dr. Rehman says.

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