It can be hard to know what “being in good shape” means these days. Most of the images you see veer towards one of two extremes- either fitness models, or the morbidly obese. More often than not, the people in these images are described in ways that make them sound closer to average than they really are- the fitness models are described as “in good shape” when they’re really in the top 1% and probably on steroids, while extremely obese people are described as being merely “overweight” when the truth is, they’ll likely be dead in five years.
So how do you cut through the bullshit and see how you really stack up? First off, don’t go by visuals. Those media images are usually misleading, by the clever use of lighting, posing, or just flat-out photoshopping. Also, different people will look different at a given body fat percentage and level of muscle mass, and everyone over-focuses on the abs anyway.
Instead, look at the numbers- body fat percentage, fat free mass index, and fat mass index.
Step 1: Body fat percentage
Don’t use one of those stupid bioeletrical impedance scales- they always underestimate body fat, and not consistently by the same amount either. Ideally, you would use an advanced method like DEXA, underwater hydrostatic weighing, or a BodPod, but those are expensive and inconvenient. Instead, you can use one of the calculators on this page to determine your body fat percentage.
Most people should use the anthropomorphic method- for that you’ll need a bathroom scale and a measuring tape. Take your measurements first thing in the morning, on an empty stomach. Stand with your feet about 4 inches apart, and let your gut hang fully out, but don’t make an active effort to push it out. This method is best for people of average or above average body fat percentage.
For people who are particularly lean- below about 15% body fat for men or 22% for women- calipers become more effective. I use these ones. Use the 3-point skinfold formula on that site if measuring yourself, or the 7-point formula if you have someone else who knows what they’re doing to take measurements for you. Make sure to always pinch the same spots, and hold the calipers exactly the same way- varying thumb position in particular can produce inconsistent measurements.
Note: Most people underestimate their body fat percentage. It’s easy, and tempting, to lie to yourself here, but it’s important not to.
Step 2: Calculate your Fat Free Mass Index and Fat Mass Index
To calculate your fat free mass index, enter your height, weight and body fat percentage into this FFMI calculator. It will give you both a raw and normalized FFMI; use the raw score.
I wasn’t able to find a fat mass index calculator, but since they’re both calculated the same way, you can get your FMI using the same FFMI calculator- just reverse your body fat percentage by subtracting it from 100%. If your body fat percentage is 20%, enter 80%, if it’s 35%, enter 65%, etc. The result will then be your fat mass index, not your fat free mass index. Again, use the raw score, not the adjusted score.
Step 3: See how you stack up
Once you have your FFMI and FMI, you can see how you stack up by looking at this FFMI and FMI percentile chart.
Note that this is based on Swiss Caucasians back in 2002- other countries would have different numbers. The Swiss are among the healthier people in the world, so it’s for the best that we’re comparing ourselves to them rather than, say, Americans. Always set a reasonably high bar for yourself.
So what do the numbers mean? Well, 38% of Swiss people are overweight, so if both numbers are near the 50th percentile, you’ll be towards the upper end of healthy- not in particularly good shape, but not medically overweight, and probably not suffering from any particular weight-related health problems.
If you get your FFMI up to the 75th percentile and your FMI down to the 25th, you’ll be in noticeably good shape, to the point where people frequently compliment you and ask for fitness advice. This is very achievable without any kind of extreme diet or lifestyle, and is probably what most people who get into fitness are aiming for.
An FFMI in the 90th percentile and FMI in the 10th percentile will mark you as a “fitness junkie.”
An FFMI in the 95th percentile and FMI in the 5th percentile will make you look like a fitness model or natural physique competitor during the off-season. Looking like a fitness model or competitor on the day of a contest or photoshoot would require pushing body fat percentage lower, though not pushing muscle mass higher.
What about bodybuilders? Male bodybuilders these days usually have a FFMI of over 30, while non-natural male fitness models and physique competitors are usually around 26-28. By comparison, most guys can’t get their FFMI over 24 or 25 without steroids, and most women can’t get over 21 or so. “Looking like a bodybuilder” is far, far beyond even the extremes of this chart, and it’s far beyond anything you’ll ever achieve naturally.
Important: while I’ve discussed both fat free mass and fat mass side by side throughout this article, reducing body fat is far more important than gaining muscle from a health standpoint, and generally also more important if your goal is just to look good.
Thankfully, losing fat is also a much faster process than gaining muscle; the average person could get their FMI down below the 25th percentile in a year with a well-designed program customized to them, while obese people may need two years. Getting your FFMI over the 75th percentile usually takes several years.
As a final thought, many people will say it’s unhealthy to fret over measurements like this. I say that’s baloney- everyone needs some way of gauging what “healthy” is. What’s unhealthy is to constantly look at photos of fitness models, celebrities or obese people to see how you stack up, which is what almost everyone does. Going by the numbers is more logical, more accurate, and provides you with much more realistic goals.