Experts Explain the Signs of Gaining Muscle vs. Fat

If you're actively trying to put on muscle, just started strength training, or have seen some recent changes in your body, you may be wondering whether you're gaining muscle or fat. It can be hard to know for sure, as body composition changes happen slowly over time; however, there are a number of ways to tell the difference between fat versus muscle weight gain. People also wonder, on the other hand, how muscle gain factors into their weight-loss goals.

To help you better understand what might be happening in your body, keep reading as experts share insight on the different signs you might be gaining muscle versus fat, whether or not muscle is "heavier" than fat, and why you can't necessarily go by the number on the scale to track your progress.

How Your Body Gains Fat vs. Muscle
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How Your Body Gains Fat vs. Muscle

At the most basic level, gaining fat on your body results from eating more calories than you burn, says exercise physiologist and NASM-certified personal trainer Gabbi Berkow, MA, CDN. So, anything eaten in excess, whether that's protein, carbs, or fat, can be stored as fat if the calories you eat are greater than the calories you burn. "Let's say, for instance, you're eating an excess of 1,000 calories than your resting metabolic rate is calling for. That needs to go somewhere. What the body does as a defense mechanism, it stores those excess calories as fat," explains Rondel King, MS, CSCS, exercise physiologist at the NYU Langone Sports Performance Center.

It's also important to note that everyone's body stores fat differently. Based on genetics, some people store more visceral fat — fat that's around the organs within the abdominal cavity — and others store more subcutaneous fat, the layer of fat between your skin and your muscles.

Gaining muscle is harder and requires a lot more work than gaining fat, Berkow notes. "You have to progressively overload your muscles by lifting weights and continually challenging yourself over time," she says. "After every workout, your muscles build more fibers so that they're better equipped to handle the stress of the next workout." But you eventually get used to the load, which is why you have to keep increasing the intensity to see progress.

Building muscle also depends on what you eat. Protein is necessary because it provides the nutrient building blocks you need to develop more muscle tissue, King explains. That eventually helps you become stronger and better withstand the workout stresses that you place on your body. Since muscle is made of protein, you have to consume plenty of protein — around one gram per pound of body weight every day — for your body to be able to build muscle, Berkow says.

Since building more muscle fibers uses up a lot of calories, you'll build the most muscle if you eat more calories than you burn, Berkow says. That means that it's possible to gain fat while building muscle. Building muscle without gaining fat is possible, but it requires "strict attention to calories and protein, and you won't put on as much muscle as you would if you ate more calories than you burned," she says. Additionally, you can't significantly "bulk up" while you're focused on losing weight due to the amount of calories required to build muscle.

Is Muscle "Heavier" Than Fat?
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Is Muscle "Heavier" Than Fat?

No, muscle is not "heavier" than fat. A pound of muscle weighs the same as a pound of fat: one pound equals one pound. However, muscle is denser than fat, Berkow says. "It has more water, protein, carbohydrates, and fats in it than fat does, but it takes up less space." Because of that, "the same amount or weight of muscle takes up less space than fat," she says. That's why gaining muscle can result in losing inches but not necessarily losing weight according to a scale, she explains.

How to Tell the Amount of Muscle and/or Fat You Have
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How to Tell the Amount of Muscle and/or Fat You Have

Measuring your body composition — how much of your body is made up of water, muscle, and fat — is the best way to assess whether you're gaining fat or muscle, Berkow says. King notes that many gyms do body composition tests of some sort before people start programs in order to get baseline values and therefore set realistic goals. Some tests include the following:

  • Bioelectrical Impedance Analysis (BIA): Body composition can be measured most easily with a BIA, "where harmless electrical currents through your body are used," Berkow explains. You even get a BIA scale that you step on or hold in your hands, but Berkow said to make sure you use it on an empty stomach and when you are hydrated "since being dehydrated can erroneously send up your body fat percentage reading."
  • Skinfold calipers: These "pinch tests" can be used to measure gains or losses in body fat.
  • DEXA scan: The dual-energy X-ray absorptiometry (DEXA) scan is a radiological scan used to measure bone density. It's the most accurate way to measure your body composition, but is often less accessible than a BIA scale, Berkow says.
  • CT scan and blood tests: These will indicate the amount of visceral fat you may have. You or a doctor can proceed to take measurements of your waist circumference since, most often, excess visceral fat can cause protrusion of the abdomen.

It's important to note that, for some people, focusing on specific body measurements can lead to an unhealthy preoccupation with exercise, food, or weight loss, and can trigger body image concerns and even disordered eating, Laura Cohen, a former registered dietitian and certified intuitive-eating practitioner, previously told POPSUGAR. If you're predisposed to or have a history of disordered eating, consider skipping any sort of quantitative body measurement. And remember that health cannot be measured solely by the number on a scale or body fat percentage, Cohen said.

If you or someone you know is struggling with disordered eating or an eating disorder, the National Eating Disorder Association (NEDA) has resources available including a 24/7 helpline at 1-800-931-2237 or by texting "NEDA" to 741741.

Signs of Gaining Fat vs. Muscle
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Signs of Gaining Fat vs. Muscle

Since you can't rely on the scale to tell you whether you're gaining muscle or fat, you may be wondering what other signs of gaining muscle vs. fat you can look out for.

Aesthetically, it may be difficult to tell if you're generally gaining muscle or fat. Just like everyone stores fat differently, everyone's body will respond differently to workouts like strength training. If you gain fat, you'll likely notice more softness, Berkow says. Conversely, when you gain muscle, you may notice that your muscles naturally look more defined and are more visible, she says. They may also look larger in size or feel "harder."

Aesthetics aside, a good way to tell if you're gaining muscle is if your workouts feel easier; if you're able to pick up heavier weights, exercise for longer, or move through your sets feels easier, those are good indicators that you're gaining muscle — and, as a result, strength.

Why Building Muscle Can Help With Fat Loss
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Why Building Muscle Can Help With Fat Loss

If your goal is to lose weight, you may wonder how muscle gain factors in. "Building muscle is what keeps your metabolism up and helps prevent weight regain, so it's absolutely key for weight loss," Berkow tells POPSUGAR. That's because muscle burns more calories than fat, so the more muscle you have, the more calories you'll burn at rest.

Preserving muscle mass is important if your goal is to lose weight, because when you're consuming fewer calories than you're expending (which is often recommended for weight loss), "your body senses that it's getting less fuel, and it slows down the number of calories it burns," Berkow says. This slows down your metabolism in order to conserve energy. Strength training and eating enough protein daily are key to keeping your metabolism up so you can therefore lose weight, Berkow says. As she mentioned before, you can't build a huge amount of muscle while trying to lose weight, since you need those extra calories to repair and build new muscle tissue.

Why a Scale Can't Properly Show Your Progress
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Why a Scale Can't Properly Show Your Progress

Even if you're losing fat, the number on the scale may not be going down if you're also gaining muscle, Berkow says. Instead of focusing on the scale alone, here are some progress indicators to pay attention to:

  • How you feel in your clothes
  • Feeling stronger
  • Improvements to your mental health
  • Loss of fat percentage (as long as that's not triggering for you)

If you're frustrated with your weight staying the same for a period of time, Berkow notes that weight-loss plateaus often occur after losing about 10 percent of your body weight. "Your body senses that you're eating less and slows down its metabolism so you burn fewer calories," she explains. And if your journey to bulk up has plateaued, you need to eat more, change your workouts, or kick up the intensity.

Things to Keep In Mind If You're Focused on Graining Muscle vs. Fat
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Things to Keep In Mind If You're Focused on Graining Muscle vs. Fat

Remember that eating nutritiously and exercising will benefit your health in so many ways, from stress relief and reduced health risks to improved mood. If significantly gaining or losing muscle or fat is your goal, that's up to you — but it's not mandatory. If you're hoping to make a significant change, make sure to speak with your doctor (and/or professionals such as registered dietitians and certified personal trainers) for personalized help.

"Gaining muscle is hard and takes work," Berkow says." You have to lift heavy, eat a lot of protein, and find the balance of lifting enough while allowing for adequate recovery." Maintaining muscle and losing fat is possible, but it's very difficult to gain muscle and lose a significant amount of fat at the same time. It's often best to focus on one at a time, she says.

To help you start training, consider following one of these beginner-friendly workout plans: