How to Lose Fat Without Losing Muscle
Everything you need to know about how to train, what and when you should eat, and the importance of a better night's sleep.
When most people talk about trying to lose weight, what they are really trying to do is lose fat.
The problem is, that requires not losing muscle—which your body naturally does when you’re in a caloric deficit. And a caloric deficit is a requisite for fat loss; you can’t lose fat without taking in fewer calories than you burn per day, says Abbie Smith-Ryan, director of the Applied Physiology Laboratory at University of North Carolina at Chapel Hill.
“If you achieve a caloric deficit to lose weight solely by cutting calories, you will lose a similar percentage of weight from fat as from muscle,” adds Heather A. Milton, senior exercise physiologist at NYU Langone’s Sports Performance Center. Which could make dieting even less attractive than it was before.
Meanwhile, a caloric surplus—eating more calories than you burn per day—is required to build muscle. Think of building muscle like laying bricks: If you want to build it up, you’re going to need more bricks. But then again, we get back to the problem of needing to get remove bricks, Jenga-style, for weight loss.
“However, you can manipulate the way the two types of body tissue, fat and muscle, are being lost during a caloric deficit by creating that deficit in a different way,” Milton says. These strategies of manipulation are plentiful—and while each helps on its own, they are most powerful when performed in concert. Here are the steps you should take.
Cut fewer calories
Obviously, if just cutting calories is going to result in so much muscle loss, you want to back away from any low-calorie diet. “In general a female should reduce calories by about 300 to 400 calories and males about 400 to 600 calories,” says Bill Campbell, director of the Performance and Physique Enhancement Laboratory at the University of South Florida. “A better way to approach this is to determine what one’s maintenance calories are, and then reduce this amount by approximately 25 percent.”
Maintenance calories are the number of calories you need to eat per day to maintain your weight at any given time, factoring in things like exercise, which we'll get to later. While the most accurate way to determine how many calories you burn per day is to spend 24 hours in a laboratory’s metabolic chamber—a room that measures the ratio of carbon dioxide in the room— the Mayo Clinic has an online tool for roughly estimating your maintenance calories. (Choose "I Want to Maintain My Current Weight.") Multiply that number by 0.75, and that's a pretty good target for losing weight slowly, he says.
That’s right: A small caloric deficit will help you lose weight slowly, which will help reduce the amount of fat-free mass that you lose, Campbell says. For example, in one study, athletes either lost 1.4 percent of their body weight per week (for a 200-pound person, that would equal 2.8 pounds per week) or 0.7 percent of their body weight per week (for the same 200-pound person, that would equal 1.4 pounds per week). Both groups lost the same amount of total weight, but while the fast weight-loss group lost 7 pounds of fat and 0.66 pounds of lean mass, the slow weight-loss group lost 11 pounds of fat and gained 2 pounds of lean mass.
Perform total-body strength training.
“The type of exercise you select is very important,” Milton says. “Cardiovascular exercise works on aerobic muscle fibers, which will increase oxygen extraction, but not necessarily change muscle mass. And you may still lose muscle mass if that's the only way you’re trying to lose weight.”
However, while strength training is most famous for building muscle while in a caloric surplus, myriad studies show that resistance training is effective at attenuating declines in muscle mass when in a caloric deficit.
Milton explains that, unlike aerobic exercise, strength training—especially heavily-loaded strength training—primarily recruits type 2 muscle fibers, which contribute to muscle mass preservation and gains. Strength training also triggers the short-term production of hormones such as human growth hormone and testosterone that aid in muscle retention and building.
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“At a minimum amount, people should perfect whole-body resistance training three days per week,” Campbell says. “Ideally, however, they should strength train five to six days per week, splitting their schedule into upper-body days and lower-body days.” What’s more, to make sure that you are optimally stimulating muscle growth, Smith-Ryan recommends performing loading exercises with roughly 80 percent or more of your 1RM, or the max weight that you could lift for one rep. Aim to perform 6 to 8 reps of each exercise in your workout routine, staying on the lower end for compound exercises and the higher end for single-joint isolation work.
Maintain or increase protein intake
When cutting calories, 9.9 times out of 10, none of them should come from protein. “Protein is the nutritional stimulus for building muscle,” Campbell says. “During a diet, it serves as the nutritional stimulus for maintaining muscle. Protein is also the most satiating nutrient—itmakes you feel full longer—and it is the least likely nutrient to be stored as fat even when eaten in excess. All of these things [make protein] a dieter’s best friend.”
For example, in one study of men who were both cutting calories and exercising, those who followed a high-protein diet lost 10.56 pounds of fat and gained 2.64 pounds of muscle. Meanwhile, those who followed low-protein diet with the same number of total calories lost 7.7 pounds of fat and gained less than a quarter pound of muscle.
How much protein you need per day depends on multiple factors, but a 2018 review concluded that, for optimal muscle growth, people should consume between 0.4 to 0.55 grams of protein per kilogram of their body weight at every meal.
“Providing a dose of 30 to 40 grams of protein every three to four hours would very rarely be a negative across the board,” adds Chad Kerksick, director of the exercise and performance nutrition laboratory at Lindenwood University in St. Charles, Missouri.
Pay attention to carbs
A low-carbohydrate diet is unnecessary for weight loss, and may even impair muscle maintenance and potential growth by limiting exercise performance, Milton says. However, in one study from the University of Illinois at Urbana-Champaign found that when women followed a 1,700-calorie diet for 10 weeks, those who maintained a 1.4:1 carbohydrate-to-protein ratio (171 grams of daily carbs 125 of protein) lost more fat while losing less lean mass (aka muscle) than those who maintained a 3.5:1 carbohydrate-to-protein ratio.
Smith-Ryan explains that you don’t need to go as low as the study did retain muscle mass while losing fat, though. She says an easy 2:1 ratio is ideal. So however much protein you eat (see above), eat double the number of grams of carbs.
Do high-intensity intervals
High-intensity interval training—such as sprints on the treadmill or stationary bike—is effective at burning calories both during exercise and afterward through excess post-exercise oxygen consumption, Milton says. And, unlike steady-state cardio, it recruits type-2 muscle fibers over type-1s, meaning it guards against muscle loss.
With the right work-to-rest ratio, HIIT can even build muscle. Smith-Ryan’s research, published in the Journal of Science and Medicine in Sport found that, over the course of a three-week training program, people who exercised at a 1:1 ratio gained significantly more muscle than those performing 2:1 intervals. For every second you spend sprinting, spend that much resting before your next bout.
Rethink pre-workout carbs and post-workout protein
Fortunately, the anabolic window (the time period after resistance training to which the body uses protein to build muscle) is actually much larger than previously believed, per one recent study. So as long as you’re getting in regular doses of protein, drinking a protein shake immediately after your workout probably isn't necessary.
And while pre-workout carbs are linked to better, harder workout performances, research shows that even pre-workout protein can be beneficial. In one study, eating 18 grams of whey protein (with 2 grams of carbs and 1.5 of fat) 20 minutes before a heavy resistance training session increased energy expenditure up to 24 hours after exercising compared to eating 19 grams of pre-workout carbs (with 1 gram of protein and 1 gram of fat).
Active recovery from exercise helps you get the most out of every workout, but the most important form of recovery that none us seem to get enough of is sleep, Milton says. She notes that the amount of sleep you get also impacts whether or not you lose muscle as you lose fat—largely by influencing hormone levels.
“Cortisol, an inflammatory hormone, increases in times of sleep deprivation or too little sleep,” she says. Cortisol in chronically too-high levels can both inhibit weight loss and promote muscle degradation. Meanwhile, human growth hormone—which aids in muscle synthesis—peaks at night during sleep, she says.
For example, in one University of Chicago-led study, when dieters got only 5.5 hours versus 8.5 hours of sleep per night, their rate of fat loss declined by 55 percent—even though they were following the same diet. And, according to research published in Diabetologia, as little as four days of sleep deprivation reduces the body’s insulin sensitivity, increasing the risk for fat storage, while reducing the body’s levels of growth hormone.
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