“Tracking weight and BMI are not great tools to measure progress, because as body composition changes, the scale may not,” explains Dave Quevedo, a NASM-certified personal trainer in Hoboken, New Jersey. “Both weight and BMI never take into account body composition, often making an active woman seem overweight – but an active woman has more muscle and less body fat than a sedentary woman.”
That means you need a different approach than your less-fit friends. “Muscle is denser than fat,” Quevedo says. Translation: It takes up less space on your frame. Look at it this way: “If you weigh an equal volume of fat and muscle, you’d be surprised that the muscle weighs almost twice as much as the fat,” he says. As you advance in your training and gain more lean muscle mass, the spikes in your weight and BMI are signs of progress, not reasons to lose motivation.
So don’t get derailed by the wrong “fatness” signals. Follow this guide to learn how to track your body fat – and where you store it – by accurately gauging your fitness progress.
The Problem with BMI
The BMI formula – a simple calculation based on your height and weight – has been around since the mid 1800s, but only in the last few decades has it gained popularity among doctors as a way to estimate a healthy body weight and mortality risks. Anything below 18.5 is considered “underweight”; 18.5 to 24.9 is “normal,” 25 to 30 is “overweight” and 30.1 or more falls into one of three obesity categories.
But as Boston-based sports nutritionist Nancy Clark, MS, RD, FACSM, author of Nancy Clark’s Sports Nutrition Guidebook points out, the BMI doesn’t distinguish between fat and muscle, and only gives you an indication of how heavy you are overall. “It’s a very poor model for active people,” she says.
In his prime, Arnold Schwarzenegger had a whopping BMI of 30.2 – “obese” according to the calculation. But anyone who’s seen “Arnie” at his best knows that he was all lean muscle, not fat.
And recent research shows that BMI can also be a false indicator of health in other ways. According to the American College of Cardiology, researchers presented their findings, which showed that individuals with a normal BMI can still have a high body-fat content, increasing their risk for cardiovascular disease and other health-related problems.
Track Your Body Fat When you begin a new fitness program or increase the intensity of your sessions in the gym, chances are you’re losing fat but gaining muscle, says Fabio Comana, MS, exercise physiologist with the American Council on Exercise. And, as you know, muscle beats fat for many reasons. “Muscle uses more calories, even at rest, so you gain the potential to boost your resting metabolic rate,” says Janet Walberg Rankin, PhD, professor in the Department of Human Nutrition, Foods and Exercise at Virginia Tech. “And muscles help us perform better, if we’re competing or just want to be able to last through our workout or exercise class.”
You shouldn’t ditch measurements altogether, however. Instead, sports nutritionists and trainers urge active women to consider where their fat is stored. That’s because women can be “skinny fat,” appearing to be healthy based on weight and height alone, but possessing pockets of fat in targeted areas that puts them at higher risk for certain health conditions.
Abdominal fat, for example, is increasingly linked to metabolic syndrome and heart disease; women whose waists are 35 inches or more have a higher risk of health problems than those with smaller waists, no matter how much they weigh. And a Danish study in Circulation found that extra body fat in women’s hips can increase the risk of venous thromboembolism, or dangerous blood clots in the veins.
So it’s important to consider your overall body fat, and where it might be landing. Though there’s no such thing as spot reduction, targeted training can help decrease your body fat and increase your muscle – leading to a leaner looking body. “Reducing your overall body fat through methods of resistance training and cardio are the best ways to change your body composition,” says Quevedo.
New technology is improving the accuracy of overall body fat measurements (see chart). Women seeking optimal fitness levels should aim for about 16 to 25 percent body fat, says Kathleen Laquale, PhD, athletic trainer at Bridgewater State College in Massachusetts. Though fitness competitors may aim for lower levels, anything below 15 percent simply can’t be sustained for the long term without health risks.
So if you need a way to gauge your fit progress by seeing a change in numbers, check up on your body fat instead of the scale. And some of the simplest techniques, from looking in the mirror to zipping up your jeans, will further help map your success and boost your confidence as you shed fat, build muscle and get on the way to reaching all your goals.
You need at least three percent fat on your body just to live, explains Kathleen Laquale, PhD, athletic trainer at Bridgewater State College in Massachusetts. Drop below 15 percent for a long time, and you risk losing your period, developing osteoporosis and suffering general fatigue. “A body-fat percentage that’s too low can be harmful to your health and well-being,” Laquale says.
Follow these guidelines for healthy body-fat percentage ranges based on your fitness level.
Top athletes 15 to 20%
Fit women 21 to 24%
Healthy/acceptable 25 to 32%
Overweight 33% plus