Muscle is the tissue worth protecting most, and it is often the first to shrink when weight comes off quickly. This tool estimates your lean body mass and skeletal muscle mass, then shows where you stand against published reference ranges.
Know your body fat percentage? Add it for a sharper estimate. If you don’t have one, our body fat calculator can give you a figure in a couple of minutes.
Pick male or female, choose metric or imperial units, then set your height and weight with the sliders. Your results appear below and show three figures: lean body mass, body fat mass, and body fat percentage. The tool uses the Boer formula, a widely used equation that predicts lean mass from height, weight, and sex alone. Because it does not measure your body directly, treat the figures as estimates. Very muscular people and those carrying more body fat may see less accurate numbers. A DEXA scan or an in-clinic body composition analysis is more precise.
You get three connected figures from the calculator. Each one describes something different, and each is helpful in its own way.
This is everything in your body that is not fat: muscle, bone, organs, blood, and water. Muscle makes up a large share of it, which is why lean mass is a practical stand-in for muscle when a scan is not available. If this number falls while you are losing weight, some of that loss is likely muscle.
This is the weight of the fat you carry, found by subtracting lean mass from your total weight. It is the part of your weight you actually want to reduce on a weight loss program. Watching it over time tells you more than the scale does, because the scale cannot separate fat from muscle.
This is your fat mass shown as a share of your total weight. It makes comparison easier, since two people at the same weight can have very different percentages. Here it is calculated from height and weight only, so use it as a rough guide. Our body fat calculator uses body measurements and gives a closer estimate.
Compare the body fat percentage from your result with the ranges below, which follow the categories published by the American Council on Exercise. Whatever is left after fat is your lean mass, so a lower percentage means a larger share of your weight is muscle, bone, and other lean tissue.
| Range | Men body fat % | Women body fat % | What It Means |
|---|---|---|---|
| Essential Fat | 2 to 5% | 10 to 13% | The minimum your body needs to protect organs and keep hormones working. Staying this low is not healthy for most people. |
| Athletes | 6 to 13% | 14 to 20% | Common in people who train hard and often. Lean mass makes up a very large share of body weight. |
| Fitness | 14 to 17% | 21 to 24% | Typical of active adults who exercise regularly and carry a good amount of muscle. |
| Average | 18 to 24% | 25 to 31% | Where many adults fall. Generally acceptable, with room to build muscle or trim fat. |
| Obesity | 25% or higher | 32% or higher | Fat makes up a large share of body weight, which raises the risk of heart and metabolic disease. Worth discussing with your provider. |
Lean body mass share = 100% minus body fat percentage. Ranges based on American Council on Exercise categories.
Muscle preservation is the most overlooked part of medical weight loss, and arguably the most important. A GLP-1 medication makes the scale go down fairly reliably. Making sure the loss is fat and not muscle takes deliberate effort.
Whenever weight drops fast, part of the loss is lean tissue, not fat. Research on GLP-1 medications has found that lean mass can make up a meaningful portion of the total weight lost, especially when eating falls off steeply and no steps are taken to hold on to muscle. These medications work by reducing appetite. That same effect makes it easy to fall short on protein without realizing it.
Muscle burns energy even at rest. When you lose it, your body uses fewer calories each day, so regaining weight gets easier and future attempts get tougher. There is a physical price too. Strength, balance, bone health, and staying independent as you age are all closely tied to how much muscle you carry.
Two habits have the best evidence behind them: eating enough protein and doing resistance training two or three times per week. Both are essential if you want most of your weight loss to come from fat. Your provider can give you a protein goal based on your weight and where you are in treatment, not a one-size-fits-all figure.
A bathroom scale shows how much you lost, not what you lost. Weight going down while muscle holds steady is very different from weight and muscle dropping together, and each calls for a different response. Keep an eye on muscle mass as well as weight throughout treatment, and share both numbers at your follow-up visits.
With a supervised program, you get a personal protein goal, a strength training plan, and regular body composition checks, so the weight that comes off is the weight you wanted gone.
Family Nurse Practitioner
“I grew tired of the traditional model of primary care. Patients deserve excellent, affordable care—delivered when they need it, not weeks later.”
Dr. Kenneth Argote is a board-certified, doctorally prepared Family Nurse Practitioner with more than 12 years of experience. He began his career at the University of South Florida, earning his Bachelor of Science in Nursing with honors before working in the Emergency Department and cardiac unit. His time caring for acutely ill patients sparked a realization: many hospitalizations could have been prevented with better primary care.
Motivated by this vision, he returned to USF to complete his Master of Science in Nursing with a focus on Family Primary Care in 2014, followed by his Doctor of Nursing Practice degree in 2019. Over the years, Dr. Argote has provided preventive, acute, and chronic care for patients of all ages while growing increasingly frustrated with how traditional insurance models limit patient outcomes.
In 2021, he founded Vital Advanced Medical Center to create a better way forward through Direct Primary Care—removing barriers, putting patients first, and providing care that is both high-quality and affordable. Today, he continues to lead the practice with a focus on whole-person health and long-term relationships.
