In this article and video we’ll discuss pretty much everything related to body fat percentages.
First we’ll talk about why it’s very helpful to know how much body fat you have, then we’ll discuss why the conventional ways to measure body fat can be very imprecise, and finally I’ll give you the methods I recommend you use.
Let’s get to it.
Should you even care about your Body Fat Percentage?
I’d argue you should.
Knowing how much body fat you have helps you make the right decisions during your cut and lean bulk cycles. If you’ve read the Path to your Goal Physique you know that building a Hollywood type physique is all about staying lean and developing great proportions.
Most people need to build 15-30 lbs (7-14kg) of muscle to get the size they want. And if they want to do that while staying lean, they must keep their cut and bulk cycles in a tight body fat percentage range.
As we discussed in the article Get Lean Before Bulking your best strategy is to start your lean bulk when you’re around 8-10%, gain weight until you hit 13-15% and then cut back to 8-10%.
Staying in the 8-15% range year round allows you to built all the size you want while never getting too fat to lose definition and good proportions. Furthermore, research shows that you make better muscle gains when you’re lean because of improved insulin sensitivity and optimal hormonal balance.
So being able to recognize when you’re 8% or 15% is important. It’s the only way you’ll know when it’s time to cut or lean bulk.
So how do you measure your body fat?
Conventional Ways to Estimate your Body Fat Percentage – Why they can be Imprecise
There a lot of methods you can use to estimate your body fat percentage:
- Bioelectrical Impedance Analysis (BIA) – such as those scales that have a metal surface and you step on the barefoot or those devices you hold with your hands at the gym
- Mathematical formulas such as the US Navy formula or the YMCA formula
- Skinfold calipers
- Bod Pod
- Hydrostatic Weighing
- Waist measurements
- and a lot more
Not all of them are equal however. Some are notoriously inaccurate, some are downright useless for the athletic population, and others are very expensive.
Let’s talk about the ones most commonly used and see how accurate they are (you may skip this part if you’re not interested):
From what I’ve seen a lot of people use BIA devices, mathematical formulas, and skinfold calipers. We’ll start with those.
These devices send an electrical current through your body and then give you a reading. They’re quick, convenient, they’re fun, but man are they unreliable.
The biggest problem with these devices is that they don’t actually scan your entire body. If you remember your high school physics classes you’ll know that electrical current always takes the path of least resistance. That means ff you use a hand-held device then the electrical current will go from your left hand through your torso and then out through your right arm. The current will not go down to your belly or legs and only then come out through your other arm.
The same thing happens if you use a BIA scale. The current will go through your legs but it will not scan your upper body properly.
We also need to consider fat distribution. Some people tend to accumulate fat in their legs and others on their belly of upper body. Well they would get different readings with a scale and with a hand-held device. The guys that don’t have a lot of fat on their legs may step on the scale and get a very low reading – but they could have a lot of fat in their upper body.
Furthermore, because the electric current always chooses the path of least resistance, it will tend to avoid fat tissue in the first place. Water is the main conductor of electricity in our body and which tissue contains the highest amount of water? That’s right, muscle tissue – that’s about 70% water. On the other hand, fat tissue contains very little water so it’s obvious that the electric current will choose to go through muscle instead of fat.
Hydration status can also mess up with the readings of BIA. You could get very different body fat percentage readings in the same day just because of your hydrations status. So in conclusion BIA is not reliable, I don’t recommend you use it.
The Navy or the YMCA formulas are also highly inaccurate and and almost nobody in the fitness industry uses them. The reason they are so inaccurate is because they were developed based on the results of other methods of determining body fat.
You can imagine that you can’t be precise doing this. That’s why the formulas are not reliable.
Skin Fold Calipers
Skin Fold Calipers can be pretty accurate actually depending on the brand and if you use them correctly. There are brands that have you measure up to 6 points on your body and others only one place. They usually give different results.
But I think the biggest problem with these calipers is that most people don’t know how to use them. You have to grab just the right amount of skin every time – not too much and not too little, and always do it in the same places.
This can be learned however and with a bit of practice and you can get a result that’s within 1 percent of your real body fat percentage.
Mike Matthews of MuscleForLife (one of the fitness authors I follow) uses this method and he likes the brand Accu-Measure.
The Bod Pod is an egg shaped chamber that measures body mass (weight) using a very precise scale, and volume by sitting inside the BOD POD. Once the overall density of the body is determined, the relative proportions of body fat and lean body mass are calculated.
The Bod Pod works well in group averages (that’s why it’s considered accurate in studies) but works horrible for individuals. Lean and muscular people often get a reading that’s 3-4% higher or lower of their actual body fat. For example Greg got a reading of 4.8% which is crazy.
DEXA is considered the gold standard because it’s very accurate.
If it’s convenient for you to get a DEXA scan, I recommend you do it. DEXA scans your entire body with X-rays and tells you very precisely how much fat you have. Then all the rest of your life you’ll have that DEXA scan as a reference point for your current body fat level.
Methods I use to Determine Body Fat Percentage
I use three methods for estimating body fat: Visual Appearance (how you look in the mirror), Waist Measurement, and Relative Strength.
How you look in the mirror is actually one of the best ways to estimate your body fat percentage.
Each body fat percentage has a certain look so you can get an idea of how much fat you have just by looking in the mirror. Check out the pictures below to get an idea of what different body fat percentages look like:
Here’s the interesting thing about your waist measurement: it goes up and down with your body fat percentage. For most people, not everybody but for most people, each body fat percentage has a certain corresponding waist measurement.
What I’ve discovered so far is that you can predict (pretty accurately) the amount of fat you have by looking at your waist. That’s why when I recommend someone to drop to a certain body fat percentage I just give them a waist measurement to shoot for. When they get there, almost every time they are at the level of leanness they’re after.
And here’s what’s even cooler. Once you get to the point here you’re happy with your level of leanness, you can measure your waist and that becomes your baseline value. Now in the future if you want to get back to that level of leanness, you know that you have to get your waist back to that point.
Weight and Height compared to Relative Strength
And the third method – I don’t use it to determine body fat percentage per se, I use it to get an idea of how much fat a client has. What I do is I look at Weight, Height, and Relative Strength.
When I get an email from someone telling me that they’re 6 feet tall and around 190lbs and they’ve been training for only 6 months I know from the start they have a good amount of fat on their body. How do I know that?
At 6 feet tall, 190lbs ripped is a very advanced level of muscle development. But this person has only been training for 6 months so there’s no way that they’re close to their genetic potential. This tells me right of the bat that they probably need to lose about 20lbs of fat to get to around 10%. I can almost guarantee it.
This works very well in the metric system. A lean guy that’s close his genetic potential for muscle building will weigh a few more kilograms than he has centimeters above 1 meter in height.
So a guy that’s 183cm tall (6 feet) will weight about 86kg when he’s very muscular and around 10% body fat. But if a beginner has a height of 183cm and weighs 83kg he has about 8-10 kilos of fat to lose to get lean.
What I’m basically saying is that if a person is heavy for their height but they are not insanely strong, they probably have a good amount of fat to lose.
What did you think about the ideas in this article? Have any questions? Anything else to add? Leave a comment below and let me know. I read and answer all comments.
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