You Can Measure Your Body Fat, but No Method Is Truly Accurate.
If you say you want to lose weight, you will probably measure your progress by stepping on the scale. But in reality you are trying to lose fat , and the number on the scale may not reflect this . There are many ways to measure body fat percentage, but they all have different levels (inaccuracies).
Knowing your body fat isn’t just for keeping track of your weight loss; it can provide a real test of your body mass index, which doctors and other professionals use to determine if you are overweight. BMI is inconsistent with body fat percentage in about 18% of people (although there is much debate over these numbers). If you have a lot of muscle, you may appear obese on the scale, even if you don’t have that much fat; if you don’t, you may have a high percentage of body fat, and it will appear as “normal” on BMI charts.
This does not mean that you need to track your body fat. For some of us, an extra number to focus on distracts from our real goals of getting healthier or stronger. If you’re just wondering where you will fall, this photo guide might help . But if you really want the most accurate body fat data science can provide, read on.
Unusual measurement methods
In fact, only a handful of people have experienced the most accurate method for determining body fat: an autopsy . So all these people are dead. Scientists have used autopsy to calibrate other methods such as those described below.
The problem is that no method can be exact, and even methods that are considered to be very accurate can differ significantly from each other. Most of the accuracy studies have been done on non-athletic white males, so this is an added caveat if you don’t fit the description.
Underwater weighing is the classic method and the basis for more sophisticated methods used in research. Your weight on land, your weight underwater, and the amount of Archimedes-style water displaced by you are all factored into the equation that gives you your body fat percentage. If you’re lucky, you can weigh underwater for as little as $ 10, but more often it costs between $ 50 and $ 100.
This method works because fat is lighter than muscle and bone. But this density differs from person to person. In one study, published in the Canadian Journal of Applied Sport Science , researchers weighed elite soccer players underwater, applied standard formulas, and came up with negative body fat percentages for some, presumably because they had tighter muscles. and bones than suggested in the equations. … Age, gender, and race also affect tissue density .
Dual X-ray Absorptiometry (DXA) is the new gold standard. This is a medical scan that is more commonly used to measure bone density, but it can also be used to measure body fat. As you lie on a table, the machine uses low-dose X-rays to create an image of your body that can then be measured. This method is very good for assessing bone and muscle density and determining fat by subtraction. The cost starts at $ 100, and in some hospitals it can go up to several hundred (not covered by insurance).
Here’s the problem: According to a review published in the European Journal of Clinical Nutrition, the two gold standards – underwater weighing and DXA scanning –differ by an average of 7% . Other studies have shown that the discrepancies are smaller. It is impossible to say what is “right,” so you simply have to live with the knowledge that accuracy is unattainable.
The BodPod , which uses air plethysmography , is a density measurement that works on the same principle as underwater weighing: by knowing how much space you take up and comparing it to your weight, we can calculate how much dense muscle is in your body. … and bone versus less dense fat. The same caveats apply: you personally may have a different body tissue density than the equations suggest. The price varies, but expect to pay around $ 50.
Are any of these methods worth it? In my opinion, only if you are really interested in indicating the most accurate possible value of the percentage of body fat and you are ready to live with the knowledge that you still will not know if this is correct. It’s hard for me to imagine this person, but let’s be honest: you are out there somewhere.
More accessible methods
Rather than chasing precision that doesn’t exist, the best way to measure body fat is probably the same way you use the scale: track changes over time. If your weight on the scale stays the same, but the amount of body fat decreases, it does not matter which number you have – the important thing is that you managed to reduce that number.
The most practical measurements are those that reflect changes in your body composition, but are cheap and simple enough that you can take them frequently. Here are your best options.
Owned by someone with experience, Skinfold Calipers are probably the best choice. The order of the measurements you take depends a lot on the person taking the measurements: do they pick the same area of skin every time they pinch? Do they use the same pressure? Depending on who you ask, it takes 50 to 100 practical measurements for someone to really succeed at it. If your gym offers this service and you may be visiting the same person every time, be sure to take advantage of this benefit.
It is not recommended to measure yourself because it is difficult to see the numbers on the caliper when you pinch your own body. There is a brand of cheap do-it-yourself calipers, although they are probably not as reliable as professional calipers .
You will also need to decide which body parts to measure and what to do with the caliper numbers when you receive them. You can choose any formula for calculating body fat . Some ask for three measurements (chest, belly, and hips are one popular combination) and some ask for seven or more. Especially if you are young and athletic, you shouldmake sure you include your thigh and calf sizes , as your upper and lower body can have very different amounts of fat.
Instead of using a calculator to estimate body fat based on measurements, some people simply add up the measurements with a caliper and track the total. If it goes up or down, you know that your body fat is changing and you don’t have to worry about whether that reflects your “real” body fat percentage or not.
Bioelectrical impedance devices , including scales with silver foot pads, have many disadvantages. They send a light electrical current through your body, assuming that fat has a different electrical resistance than other tissues. This is not a bad theory, but in practice there are many variations, even from day to day.
Hydration status can alter your bioelectrical performance. This means your body fat readings can change from start to finish; for women, it may vary depending on which monthly cycle you take measurements. If you want to use this method, you must be extremely consistent: measure every time at the same time of the day, in the same conditions (for example, after breakfast, but before training) and at the same time of the month.
The type of device also matters: The foot pad scale only passes current through your feet. the portable device only uses your upper body. And even if you use the device constantly, the results may still vary . So if it seems to you that you are losing weight, but the device does not show large changes in numbers, do not be discouraged.
Tape measure methods use the size of different body parts to calculate your body fat. Standard caveats apply: the equation can be based on people who are different from you, and changing body shape can make a big difference in results. The tape measure also cannot tell muscle from fat. For example, if you’re gaining hip inches, is that good (more muscle) or bad (more fat)? A caliper does not have this problem, because when the skin is pinched, the fat is separated from the muscles.
Bottom line
Expensive laboratory methods are the most accurate, but none of them will guarantee you the correct body fat percentage. If you want to track your body fat cheaply, a caliper is probably the best compromise between convenience and accuracy. Don’t forget that you can also measure your progress against this old expectation: noticing if your clothes are getting looser or tighter.
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