You're Losing Weight, But How Much Is Fat? Here's How to Tell

Having too much body fat — even if you're at a healthy weight — can put you at an increased risk for health issues like diabetes and heart disease. But how do you know if your body fat is too high? And, when you start losing weight, how can you calculate the amount of body fat you're really losing?

There are different methods for measuring body fat in the body, along with strategies you can use to calculate your body fat percentage and how much fat you're losing. We'll break them down here.

Body fat is just one part of body composition, along with muscle, bone and other components, Mir Ali, MD, general and bariatric surgeon at the MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California, tells LIVESTRONG.com.

"Body fat is the total amount of fat in the body compared to total body weight," says Kristi Veltkamp, RDN, a dietitian with Spectrum Health in Grand Rapids, Michigan. For example, she says, if you have 30 pounds of fat in your body and you weigh 150 pounds, then you have 20 percent body fat.

And although many people tend to think of fat as a negative thing, the body actually requires a certain amount of fat in order to function. "Having a certain level of body fat is essential for health.," says Veltkamp. "Women require about 10 to 13 percent essential fat and men 2 to 5 percent. The rest is storage fat and is also beneficial for protecting internal organs and for insulation."

According to Veltkamp and Dr. Ali, the ideal body fat percentage for men ranges from about 8 to 24 percent, while the ideal body fat percentage for women is 20 to 35 percent. There isn't one set standard for healthy body fat in all individuals, since many different factors play into this number. Athletes, for example, will have lower body fat, and body fat ranges will also differ in individuals throughout their life, as older people will lose muscle tissue as they age and replace it with body fat, per the U.S. National Library of Medicine.

Dr. Ali explains that body fat percentage is a better measure of someone's overall health than weight — but unfortunately, measuring body fat is a bit more complicated than hopping on a scale.

So, how can you calculate how much body fat you have, or how much you have lost? There are three main methods that can help you estimate your body fat: By measuring skinfold thickness, using Bioelectrical Impedance Analysis (BIA) and via medical methods. Following is a rundown of each.

To measure body fat using the skinfold method, a nutrition or fitness professional uses a tool called calipers to pinch skin and fat at different points on the body and then plugs these measurements into an equation that estimates body fat. The accuracy of this method will depend on the skill of the person doing the measuring, and it tends to be less accurate for individuals who are overweight or have excess skin. The American Council on Exercise (ACE) estimates that the skinfold method has an error rate of 3.5 percent.

Bioelectrical impedance uses a device available at many gyms and healthcare facilities that sends an electrical signal through your body to estimates body fat percentage based on how long it takes the signal to pass through your body. Veltkamp warns that this method can vary greatly in both accuracy and cost.

The most accurate methods to measure body fat, according to Veltkamp, are underwater weighing, air displacement plethysmography or dual-energy X-ray absorptiometry (DEXA). Although these methods are the most accurate, they are costly and not feasible for most people to use on an everyday basis.

If you don't have access to any of the above methods to measure body fat, you can get a rough estimate by using an online body fat calculator. LIVESTRONG.com's Body Fat Calculator, for example, uses your sex as well as key body measurements to approximate your total fat mass.

Harvard Health Publishing also recommends paying particular attention to your waist size, as abdominal fat in particular can be especially dangerous to health. You may have an overall healthy body fat percentage, for example, but if the majority of your fat is concentrated in the abdominal area, you may be at higher risk for complications such as heart disease and diabetes.

If you're losing weight, the easiest way to calculate the percentage of body fat you've lost is to take your starting percentage of body fat and subtract your ending percentage of body fat. But of course, not everyone has these measurements.

If you want to see how much fat you need to lose to reach your desired fat percentage, you can use your starting body fat percentage — or an estimate, based on your age and sex — to figure out approximately much body weight you'll need to shed.

The ACE provides the following formula for this purpose:

Your desired body weight = your current lean body weight / (1 minus your desired lean mass percentage in decimal form)

So, let's say for example:

• ‌Your current weight:‌ 160 pounds
• ‌Your current body fat percentage:‌ 30 percent
• ‌You want:‌ 25 percent body fat percentage

Weight (160) x body fat percentage (.3) = 48 pounds, which means you currently have 48 pounds of body fat.

If you want to decrease your body fat percentage to 25 percent, you subtract 0.25 from 1 to get 0.75 — your desired lean mass percentage in decimal form. If you have 48 pounds of body fat, that means that the rest of you is 112 pounds of lean body mass, so you can plug that into the formula to get:

112/(1 - 0.25) or in other words 112/.75 = 149 pounds

160 - 149 = 11 pounds of fat

Since your starting weight is 160 pounds and your desired body weight for your target body fat percentage is 149 pounds, you'll need to lose 11 pounds of fat to reach your goal. But as you take steps to reduce your body fat, it can be helpful to work with both a dietitian and a fitness professional to be sure that the weight you are losing is actually fat and not muscle.

If you don't have the resources to measure your body fat, Veltkamp suggests using measurements of your waist, hip and bicep circumferences to track your progress. That way, if you are trying to lose body fat, you can see the inches you've lost, which may be a better indicator than the pounds on the scale.

If you're looking to reduce the amount of body fat you have, Veltkamp recommends the following tips:

• ‌Increase your protein.‌ According to Veltkamp, when you cut down on calories, your body starts to use protein and muscle for energy, so increasing your protein intake will help prevent muscle loss. "Remember, we don't want to lose ‌weight‌, but body fat," she notes. "A lot of people lose muscle with severe diets and think they are doing well losing but are actually losing a lot of muscle."
• ‌Keep weight loss to 1 to 2 pounds per week.‌ If you lose more than that, it's more likely to be muscle that you're losing, not body fat, she says.
• ‌Add cardio exercise and resistance training‌ to preserve muscle mass and help boost your metabolism.

Veltkamp adds that while fat-loss strategies will be similar for male and females, it is important for women to remember that they will have naturally higher body fat levels than men, due to factors such as breast tissue. A woman's higher body fat percentage is essential for hormone function, including childbearing, and varies from person to person based on genetics.

"Trying to lose this essential fat can be dangerous and lead to eating disorders, irregular menstrual function, bone loss/fractures, infertility, impaired growth, high cholesterol and increased cardiovascular risk," she notes.

It's also possible that you can make a significant change in your levels of body fat without seeing any real change in how much you weigh. As a September 2018 study in ‌European Journal of Clinical Nutrition‌ found, introducing an exercise program to individuals who were overweight didn't drastically affect their weight but still significantly reduced their levels of body fat, and thus, improved their health.