When you step on the scale, the number you see can affect your day, your mood, and your decisions about your health. The trouble is, that number doesn’t tell the full story.
Not all weight loss is created equal—there’s a big difference between losing fat and simply losing weight, and understanding this can be crucial to your weight loss journey. While many people say they want to lose weight, what they really mean is they want to lose fat, not muscle, water, or bone, according to Sue DeCotiis, M.D., a board-certified weight loss physician.
So, how can you be sure that you’re losing the right kind of weight—the fat that affects your health—without sacrificing muscle, which is essential for your body’s strength and metabolism?
About the Experts
Sue DeCotiis, M.D., is a physician who specializes in medical weight loss and is triple board-certified in obesity medicine. James King III, C.S.C.S., PN-1, is a certified fitness trainer specializing in body recomposition, who has personally lost over 50 pounds.
What’s the Difference Between Fat and Weight Loss?
Fat mass refers to the total amount of fat in your body. This includes the essential fat your body needs to function (like cushioning your organs and regulating your hormones) and the stored fat your body holds onto for energy. The goal of fat loss is to reduce the latter—this is the fat that carries health risks.
Total body mass, on the other hand, includes fat mass as well as lean tissue (like muscles, bones, and organs), and water. Weight loss refers to the reduction in total body mass, but that doesn’t mean fat loss. When the number on the scale drops, you could be losing muscle or simply dropping water weight, which doesn’t necessarily lead to long-term health improvements.
Should You Aim to Lose Fat or Weight?
If your goal is to improve your health, aim for fat loss, not just weight loss. Why? Muscle is essential to your overall health, so, you don’t want to lose it (1). “Muscle supports your bones, and provides strength for everyday activities,” says Decotiis.
More importantly, muscle is a calorie-burning powerhouse. “The less you have, the fewer calories you burn at rest (2),” Decotiis adds. In other words, the more muscle you have, the easier it is to maintain a healthy weight and body composition.
Holding onto muscle becomes even more important with age. “After the age of 30, we naturally begin to lose muscle in a process known as sarcopenia, which can slow metabolism and decrease strength (3), ” says certified fitness trainer James King.
But what if you have a lot of weight to lose and you want to reduce the health risks associated with obesity? Your primary goal should still be fat loss while maintaining or building muscle. “Even people with obesity have muscle they can’t afford to lose,” says Decotiis.
Can You Lose Fat Without Losing Weight?
It might sound counterintuitive, but yes, you can lose fat without seeing a change on the scale. It’s called body recomposition (4). In her practice, Decotiis sees it happen regularly.
For example, if you’re strength training and eating a high-protein diet., your body may become leaner and your clothes may fit better, even if the scale hasn’t budged. This is because muscle is denser than fat. So while you’re losing inches, your weight might stay the same.
This is a big reason why relying solely on the scale can be misleading.
If you have the urge to track progress with daily weigh-ins, don’t, per Decotiis. You’ll drive yourself crazy with normal daily fluctuations in water weight, which doesn’t give a clear picture of what matters most—fat loss.
Unfortunately, a regular bathroom scale won’t tell you whether you’re losing fat or muscle. There are better tools for assessing body composition.
Progress photos: Take full-body photos from the front, back, and side. Do this regularly, wearing the same clothes and standing at the same angle, to gauge progress over time.
Waist-to-hip ratio (WHR): Divide your waist measurement by your hip measurement to calculate your WHR. Men should aim for a WHR below 0.9; women below 0.85. Track and log your WHR regularly to see progress over time.
DEXA (dual-energy X-ray absorptiometry) scans: These scans are considered the gold standard for measuring body fat, muscle, and bone density. Ask your GP for a DEXA scan, but keep in mind that most insurance plans only cover it if deemed medically necessary. “It’s not as convenient as other methods, but it’s much more accurate,” says King.
Body fat scales: These scales use bioelectrical impedance to estimate your body fat percentage. While less accurate than a DEXA scan, they can give you a general idea of how your body composition is changing over time. You’ll find the most accurate body fat scales in the office of doctors who specialize in weight loss, according to Decotiis.
Skinfold calipers: These affordable tools measure the thickness of fat at specific points on your body. While simple to use, accuracy depends on your technique, so you may need to practice.
Whatever method you choose, the key is to track your progress over time rather than relying on a single measurement. This will give you a clearer picture of whether you’re losing fat, muscle, or water weight.
How to Lose Fat and Maintain Muscle
“Losing muscle is like trading in a sports car for a tricycle—things slow down, and you’re not getting anywhere fast,” says King. Here are expert-backed strategies to make sure that doesn’t happen.
Strength train
If you want to preserve your muscle mass, strength training is non-negotiable. “Focus on compound movements like squats, pushes, pulls, and hinges to maintain muscle while losing fat,” says King. He recommends three to four compound lifts per workout, along with some isolation exercises for smaller muscle groups like biceps, triceps, and shoulders.
King suggests strength training at least three times a week. “Even in a caloric deficit, progressive overload—increasing weight, reps, or sets over time—is key to signaling your body to preserve muscle (5),” he explains.
Achieve a calorie deficit
To lose fat, you need to consume fewer calories than you burn. However, cutting too many calories can lead to muscle loss and hanger that can make it harder to stick with your plan. A moderate calorie deficit of about 300 to 500 calories per day is typically enough to promote fat loss without sacrificing muscle.
Prioritizing proteinis also key, says King. Protein is essential for muscle repair and growth and helps keep you full, so you don’t overeat (6).
Getting about 0.7 grams of protein per pound of body weight has been shown to promote more muscle gain than lower protein intakes (7). King encourages his clients to eat a little more than that—1 to 1.2 grams of protein per pound of body weight per day. For a 150-pound person, that’s 150 to 180 grams per day.
Decotiis likes to keep things simple. With every meal, focus on a good source of lean protein. Think chicken breast, cottage cheese, salmon, or tofu.
Prioritize recovery
Your muscles need time to repair and grow after a workout. Without enough rest, you’re at risk of overtraining, which can lead to muscle loss. “Prioritize recovery: get enough sleep, stretch, and manage stress,” says King.
Studies show sleep, especially slow-wave sleep, helps build and maintain muscle (8). That’s because levels of human growth hormone are present in relatively high amounts during this deep sleep phase. “Enough sleep” may be more than you think—seven to nine hours a night for most adults (9).
“Improve sleep quality by creating a cool, dark room and minimizing electronics before bed,” says King.
The Bottom Line
For overall health, focus on fat loss (or losing only fat), rather than weight loss (or a reduction in total body mass including fat, bone, muscle, and water). Losing fat while maintaining muscle will help you look and feel stronger, and support your metabolism. While the scale can provide some insight into your progress, it’s not the whole story. Tools like DEXA scans, body fat scales, and even progress photos give a clearer picture of whether you’re shedding fat or total body mass so you can adjust your diet and exercise accordingly.
