Body fat is a common concern among some Service Members. Total body mass is made up of different tissues and fluids, including bone, muscle, fat, organs, skin, and blood. For simplicity, we categorize body composition into 2 main components: lean, fat-free mass (muscle, bones, organs) and fat mass. Your body-fat percentage (BF%) is how much of your total body composition is fat mass. Fat mass is the easiest component to measure, and it has the most well-defined upper and lower limits associated with health problems.
Body fat is essential for normal body functions, especially for women who require more body fat than men to produce reproductive hormones. But there’s an upper limit to body fat where it becomes unhealthy. Higher levels of body fat are associated with risk for long-term diseases such as heart disease, various forms of cancer, and high blood pressure.
Obesity caused by excess body fat can lead to hormone dysfunctions. For example, leptin—the hormone that controls when you feel full when you eat—is produced in your body fat. But if you have too much body fat, your body becomes less sensitive to leptin. (This is similar to how your body is less sensitive to insulin if you have Type 2 diabetes.) This contributes to a vicious cycle of overeating because you don’t feel full. Then your body produces more fat from taking in too many calories, thus continuing leptin insensitivity.
For optimal military fitness, it’s important to maintain a healthy level of body fat. Too much, or too little, body fat can have a negative effect on your performance and can lead to long-term risk of chronic disease.
High levels of body fat can also hurt your quality of life. Obesity can lead to conditions such as back and knee pain, which can limit your mobility and make it hard to perform everyday functions.
The “ideal” body fat percentage is a wide range that changes based on your age and activity level. For young (ages 20–39) men, a healthy BF% is about 10–20%, and up to 25% for middle-aged (40–59) men. The BF% ranges are higher for women—15–30% for young women, and up to 38% for middle-aged women. Some athletes are encouraged to be on the low end of their healthy ranges because it might benefit athletic performance. For example, endurance athletes usually have a very lean body composition because they use so much energy and burn so much fat during their long exercise sessions. A competitive male marathon runner will almost never have 20–25% body fat. Competitive bodybuilders will cut their body fat below 10% (sometimes as low as 5%) for short periods of time around their competitions. (It’s impossible to maintain this extreme body composition, and it provides little to no functional benefit.)
Your body uses mostly fat for energy when you’re not exercising, so you need very little body fat when you’re at rest. Body fat below 5% for men and 8% for women is considered unhealthy—this is the minimum body fat required for basic life functions such as hormone production, fat-soluble vitamin absorption and storage (vitamins A, D, E, and K), and body-temperature regulation. For women, too little body fat can also lead to irregular menstrual cycles and difficulty getting pregnant. Experts say women need a minimum of 17% body fat to menstruate, and a minimum of 22% for a regular cycle.
In addition to reproduction, your sex hormones are responsible for body functions such as bone and muscle growth. Men and women with too little body fat can experience abnormal sex-hormone production. Poor bone health and other negative effects related to relative energy deficiency in sport are tied to sex hormone function, especially in physically active people.
Body-fat percentage for abs
If your goal is 6-pack abs, you need low levels of body fat to see them—less than 15% for men and less than 20% for women. A strict eating and exercise plan is needed to maintain these low levels of body fat, which can be difficult to sustain in the long term. While some people may find visible abs attractive, it has little functional benefit. The purpose of the rectus abdominis muscle—the “6-pack abs”—is primarily to forward-flex the spine and limit backward hyperextension while rotating your pelvis backwards. The rectus abdominis also helps you breathe, by helping you forcefully exhale. Seeing the muscle has little bearing on its ability to function.
Ideal body-fat percentage
How do you determine your “ideal” body composition? The best place to start is to be in the healthy range. For most people, exact body-fat percentage doesn’t matter, as long as it’s not too high or low. Some health conditions create a need for more specificity with your body composition. For example, most women need at least 22% body fat to menstruate regularly. Through discussions with their doctors, some women might find being closer to 25% body fat leads to the best cycle regularity.
Unless your doctor diagnoses you with a special health condition, your ideal body composition is whatever allows you to feel and perform your best without resorting to drastic measures such as abnormal eating patterns, calorie restriction, or excessive exercise. Everyone’s different, so there’s no single, ideal body-fat percentage to recommend within the healthy range. Some people might be comfortable and perform well near the low end of the healthy range, while others are comfortable and perform well in the middle- or even the high end.
DoD Instruction (DoDI) 1308.3 sets the basic rules for how strict military body fat standards can be. The maximum BF% set by the Services must be within 18–26% for men and 26–36% for women, but specific body-fat standards vary by branch. For information on how BF% is measured, read HPRC’s article on measuring body composition.
Updated: June 25, 2025
