Body Fat: More Than Meets the Eye

“Fat” is such a derisive, triggering word today, but the fact is that we all have body fat and Thank Goodness because we wouldn’t be alive without it. It keeps us warm, cushions our organs, and provides a source of energy to sustain us should we need to fast. 

Essential fat, the type you need to stay alive, can be found in your nerves, brain, and bone marrow. It also protects your organs. You’ve almost certainly heard the term “lean body mass.” This is the mass that makes up your bones, muscles, organs, and tissues — all of which contain a bit of life-sustaining essential fat. Lean body mass allows your body to burn calories even at rest. 

On the other hand, storage fat is found both around the organs and under the skin. You can lose a good bit of storage fat and stay alive (via Withings). It’s visceral fat, the storage fat that wraps around your abdomen and internal organs that is most detrimental to good health. 

How Body Fat is Measured at a Fitness Center or Provider’s Office

If you have your body fat measured at a fitness center, the employee will most likely utilize either skinfold thickness or bioelectrical impedance (via Harvard T.H. Chan School of Public Health). Skinfold thickness is measured by pinching the skin and fat with calipers at the waist, back, thighs, arms, and shoulder blades. Your body fat percentage is calculated by punching these measurements into an equation. The problem is that if your BMI is over 35, this method will be difficult at best. 

Bioelectrical impedance is pretty much what it sounds like — a tiny current of electricity is sent through the body, and the resistance provided by body fat is measured. It’s perfectly safe, although it does sound a bit sci-fi, and it’s a very fast process. If you’re already on an effective weight loss diet or are dehydrated because of a recent illness, travel, or a competitive sporting event, for example, the results won’t be as accurate. Like skinfold thickness, it’s also not as accurate in people with a BMI of 35 or higher. 

How Body Fat is Measured in Research 

It’s possible that if you live near a research hospital or other science facility, you’ll be able to sign up for a more sophisticated body fat analysis. If you’ve ever participated in a dunking game at the local fair, you’re well-prepared for underwater weighing (densitometry), wherein you’re weighed in the air and then weighed again once you’re underwater in a tank. Formulas are then used to estimate body volume, density, and body fat percentage (via Harvard T.H. Chan School of Public Health). This method works because fat is less dense in water, so the higher your body fat is, the lower your body density. Researchers prefer to do underwater weighing on young-ish adults with a BMI less than 40. 

Another, similar method used in research is the complicated-sounding air-displacement plethysmography, which is done in the air instead of a water tank. However, you’ll still be wearing a bathing suit. Instead of relying on the density of fat in water, these machines utilize changes in air pressure, which is measured before entering the chamber and once you’re seated inside it. In contrast to densitometry, plethysmography can be used for children, older adults, and those with a BMI over 40. 

The same DEXA scan used to measure bone density can also estimate the amount of fat in your body. Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) are the most accurate method for determining fat and lean muscle mass, but they are only used in research settings. Unlike other methods, CT and MRI scans can differentiate between different types of fat, such as the dangerous fat that wraps around internal organs and the not-as-dangerous fat that lies right below the skin. 

Body Fat vs. Body Mass Index (BMI)

The BMI has fallen out of favor in recent years, and for good reason, although it’s probably still the best method that your doctor has available to them for determining your weight-related health risks. The problem with BMI is that it only uses height and weight. Unlike the measurements described above, nothing about your body composition is considered. You could be 200 pounds of muscle or 200 pounds of fat, and your BMI would be the same

Still, for most average Americans, the BMI is a convenient way to quickly determine your risk for several diseases, including heart disease and type 2 diabetes. However, many health experts believe that waist circumference and waist-to-height ratio are even better measurements for predicting the risk of these conditions. Harry DuVal, Ph.D., associate professor of exercise science at the University of Georgia, when speaking to WebMD, stated, “Fat percentages just don’t have enough research behind them yet to tell you how much risk of disease you face.” This might be changing, though, as research on how to best use body-fat percentage continues to evolve. 

Another consideration is that racial and sex differences are also not taken into account by BMI calculations (via Medical News Today). Nick Trefethen, Professor of Numerical Analysis at Oxford University’s Mathematical Institute, believes that BMI overcalculates the BMI in tall people and underestimates it in short people.

Ideal Body Fat Percentages

The parameters for interpreting body fat measurements change based on age and gender. For example, on some charts, a woman between the ages of 20-29 has “excellent” body fat when it falls between 14 and 16.5%, while for a woman over the age of 60, the same classification is 14 to 23.2%. On the other hand, a man between the ages of 40 and 49 is considered to have dangerously high body fat if it is over 26.7%. Still, this level isn’t reached for a woman in the same age range until her body fat percentage creeps over 31.3% (via Medical News Today). 

Other types of categorization for body fat percentage use gender and fitness level. For example, according to The American Council on Exercise, female athletes should strive for a body fat percentage between 14 and 20% while the acceptable range for non-athletes is 25-31% (via Healthline). 

Visceral Fat is Especially Dangerous

Perhaps you’ve heard the term “visceral fat” or been told that you have an “apple” shaped body. You might have wondered what the heck it means and whether or not you should be offended. This fat is known as visceral fat. It is of particular concern because, as it invades our abdominal cavity, it puts extra padding around the abdominal organs, such as the liver and kidneys (via Harvard Health Publishing). As we age, most of us sadly pack on a few pounds, and that extra weight tends to land right around the middle of our bodies. 

People with an abundance of abdominal fat tend to have higher cholesterol levels and are more likely to struggle with insulin resistance and fatty liver disease. This type of fat is also linked to metabolic issues and increases the chances of your having to deal with heart disease. In women, particularly, it is also associated with both breast cancer and gallbladder disease.

It’s not your fault if food tends to go straight to your waistline — to some extent, you’re a victim of your genes and hormonal makeup. Still, visceral fat is shed through the same efforts as subcutaneous fat (the layer of fat right below the skin) — with hard work and lasting changes in your diet and exercise regimen. Fat isn’t just something unpleasant that makes your pants tight. Fat can be thought of as an organ or gland capable of producing and altering hormone levels and releasing immune chemicals that affect everything from blood pressure to cancer risk. 

When Weight Goes Down, and Body Fat Goes Up

People who are extremely dedicated to their diet and exercise plans are often surprised to see that their body fat increases while the pounds fall off. This results from water loss, increased fat storage (the body likes a little padding in case of emergency), and the body’s preference for burning sugar instead of fat during physical activity. Take heart, though—as healthy weight loss continues, your body will have no choice but to dig into those stubborn fat stores (via Livestrong).

If you’re on a crash diet or losing weight too fast without doing any muscle-strengthening workouts, you will sacrifice muscle and might even lose some valuable bone, which will exacerbate the increase in body fat percentage. This can also occur if your diet is based around simple carbohydrates or contains many highly processed foods like buttery crackers and cookies. Drinking too much alcohol has a similar effect.

The Color of Your Body Fat Matters

The carbohydrate, protein, and fat that you ingest are used to power everything your body does — from breathing and keeping your heart pumping to climbing the stairs in your home and getting you through that tough spinning class. Until a few years ago, fat was fat, to put it bluntly. Then researchers discovered that some fat is brown, and some, the majority of what humans carry around, is white. Brown fat is metabolically active and breaks down blood sugar and stored body fat to produce the energy necessary to maintain normal body temperature. Because of this, people who are exposed to cold environments have more active brown fat. White fat, on the other hand, is what causes obesity. Researchers believe that if we can figure out a way to turn some of our white fat into brown fat, our health would greatly improve. 

A study done at the University of California in San Francisco did just that — activated the brown fat in 33 young men for two hours. Before the exposure to cold temperatures, the researchers had already determined that 17 of the men had higher brown fat activity than the other 16. What shocked the researchers was the discovery that the young men with the high brown fat activity before cold exposure had lower branched-chain amino acids (BCAAs)  in their blood. The same finding has been seen in obese mice, as well. This was so surprising because BCAAs are generally a sign of good health. 

In fact, low levels of these amino acids are typically associated with obesity and insulin resistance in people and lab animals. It turns out that the BCAAs were higher in the blood of individuals and mice with lower brown fat levels because, in individuals with more brown fat, those BCAAs are shuttled out of the blood and into the mitochondria (the powerhouse inside every cell in your body) to produce energy and generate heat. 

Therefore, it seems likely that if scientists can engineer a way to get the BCAAs from the blood and into the cells, it could lead to the development of novel treatments for obesity and diabetes. 

Dangers of Too Much Body Fat

Most of us have heard of the health risks associated with excess weight in general, including type 2 diabetes, high blood pressure, heart disease, and stroke. Health experts have also gotten the word out that extra weight contributes to the development of sleep apnea, fatty liver disease, osteoarthritis, gallbladder disease, kidney disease, and some forms of cancer (via the National Institute of Diabetes and Digestive and Kidney Diseases). 


When we see skinny people, we generally assume that they are healthy and resistant to these maladies. We might even be jealous of their slender body. All might not be what it appears. Perhaps you’ve heard the term “skinny fat” and wondered what it means. Although individuals with this problem appear thin and healthy on the outside, their body fat percentage is surprisingly high, while their muscle mass is lower than expected. Skinny fat people probably don’t realize it, but they are at risk for developing insulin resistance, high cholesterol, high triglycerides, and high blood pressure (via Healthline).

People genetically predisposed to be thin often feel like they don’t need to exercise because the emphasis on health in America tends to be very weight-focused. But when you exercise, your body benefits in ways that go way beyond calorie burn. For example, during physical activity, your body releases hormones that stimulate muscle growth and make your body more sensitive to insulin, so blood glucose levels stay low. Similarly, thin people who feel that they don’t need to think about what they eat as much as overweight people might eat way more sugar than they should, thus increasing their risk of developing a plethora of chronic diseases.

Dangers of Too Little Body Fat

The saying “You can never be too rich or too thin” sadly rings true for many people who are on a never-ending search for the kind of skinny only seen in photoshopped images. The most common causes of “underfat” are chronic illnesses, such as cancer, and eating disorders. Individuals whose body fat dips too low, below 10-13% in women or 2-5% in men, could develop deficiencies of the fat-soluble vitamins (vitamins A, D, E, and K). 

Worse, low body fats stresses the cardiovascular system and increases the risk of several diseases of the gastrointestinal and nervous systems (via Livestrong). The immune system does not function as well in underweight people, and the risk of infection rises as body fat percentage drops. Low body fat interrupts the normal menstrual cycle and makes pregnancy less likely to occur. If an underweight woman successfully gets pregnant, her chances of miscarriage are higher than they would otherwise be. Brain fog and fatigue can also harm school and work performance for those with a low body fat percentage. 

How to Decrease Body Fat

Richard Weil, MEd, CDE, director of the New York Obesity Research Center Weight Loss Program at St. Luke’s Roosevelt Hospital Center in New York City, told Medicinenet that, by following a healthy weight loss program, you could lose 1 to 3% of your body fat each month. He points out, however, that how much you’ll lose is a very individual thing “because there are so many variables that affect body composition, including age, gender, amount of body fat and muscle mass that you start with, and a myriad of hormones that control how efficient your body is at storing fat and metabolizing it.” 

To lose body fat, you’re going to have to increase muscle gain. That means exercise! According to Jim White, a registered dietitian, exercise physiologist, and owner of Jim White Fitness & Nutrition Studios in Virginia was quoted in US News, “We need to include at least two days of weight training a week to maintain muscle mass and three or more times a week to build muscle.”  He adds that exercises that work for multiple muscle groups simultaneously are especially effective for the maintenance and growth of muscle and that while high-intensity interval training (HIIT) will help to “burn calories and reduce body fat while still building muscle,” he recommends only doing this type of workout once or twice a week. 

Don’t slash your calories too much, either. By being a bit more conservative, you’ll be able to hold on to that very-important lean muscle mass. Your muscle will need plenty of protein for fuel, so aim to eat roughly 100 grams each day, divided between your meals and snacks. You don’t want to, for example, eat primarily carbs at breakfast and lunch and then only eat protein at dinner. Your body can only process so much protein at a time, so make sure that you space your intake out throughout the day. 

How to Increase Body Fat

People who struggle to keep their weight down are probably rolling their eyes right now and thinking of the delicious foods (chocolate cake and French fries) they would eat if needed to gain weight. Yet, being underweight is extremely detrimental to good health, and some people truly struggle to put on pounds without wrecking their bodies. When gaining weight healthfully, the goal is to put on muscle and subcutaneous fat while avoiding the dangerous visceral fat that we discussed above (via Healthline). This can be very tricky and professional guidance is often needed. 

You need to be sure to consume plenty of high-protein foods such as meat, poultry, fish, beans, and nuts. If these foods don’t appeal to you, there are several nutritious protein supplements on the market. Your carbohydrate choices should be whole-grain and high-fiber. Focus on healthy fats such as avocado, nuts, olives, and plant-based oils. Essentially, you want to make every bite count and pack in as many vitamins, minerals, and phytonutrients as possible. Adding sauces and condiments is another way to boost your calorie intake. For example, adding hummus, peanut butter, or guacamole to your sandwich can boost the calorie and nutrient content. 

Medications to Decrease Body Fat

Sometimes exercise and diet aren’t enough for effective weight loss, and medications must be considered. These are usually reserved for individuals with a BMI over 30 or those with a BMI over 27 and serious medical problems associated with being overweight, such as heart disease or diabetes. However, medical professionals caution that the medications should be combined with lifestyle changes for sustainable weight loss. Using a combo approach, you can expect to lose 3-7% more of your body weight than you would if you just made lifestyle changes without medications. 

The most common side effects of these medications are gastrointestinal and can include nausea, constipation, or diarrhea (via the Mayo Clinic). Three weight-loss drugs work by decreasing appetite or increasing a feeling of satiety (fullness). These medications are Bupropion-naltrexone (Contrave), Liraglutide (Saxenda), and Phentermine-topiramate (Qsymia). 

Alternatively, Orlistat (Xenical) works by interrupting fat absorption. Orlistat is available over-the-counter as Alli. Because it essentially stops fat from being absorbed by the body, it can cause flatulence and loose stools. Be warned that people have had bathroom accidents if they eat a high-fat meal while taking this medication. Much more scarily, a few causes of serious liver injury have been reported by users, although a link hasn’t been definitively proven. 

The Myth of Spot Reduction

Maybe you spent your youth doing hamstring curls and sit-ups, hoping to get rid of your “problem areas” once and for all. Jane Fonda, Denise Richards, and many other classical exercise instructors urged us to do this in the 80s and 90s’. You probably were disheartened to discover that it didn’t work for you, but it turns out that it wasn’t your fault! Unfortunately, you can’t rid your body of fat just in one place. The only way to rid yourself of a muffin-top or a love handle is to lose weight all over. Many muscles that we try to target through isolated exercises, such as the triceps, are very small and don’t burn a lot of calories or build your fitness level by much (ACE Fitness). 

In an article written for Verywell, Paige Waehner, a certified personal trainer, explains that “The body doesn’t only draw energy from the cells in the area you’re working. It gets energy from the body as a whole, which means that leg lifts alone won’t do much for removing fat from the thighs. However, exercising your legs can increase strength and endurance in your lower body.” In other words, those classic exercises are still worth your time.