Yesterday I talked about how much protein we really need and why I feel eating 1 gram per pound of lean body weight appears to be the best starting place. I wanted to expand on that today with a little how-to:
How to Calculate Your Lean Body Mass
Figuring out your lean body mass and body fat percentage is something that should be simple but rarely is. There are a few ways to do this, but many of them are unreliable. I've had online body fat calculators tell me I have anywhere from 16% to 36% body fat. I know I'm really somewhere in between, so you really have to take some of these numbers with a grain of salt.
This is the free body fat percentage calculator I use. It's been the most accurate one I've found online. It takes into account waist and neck measurement (plus hip measurement for women), in addition to height and weight. It also does the lean body mass calculation for you, which is convenient. Hopefully you'll find this accurate, too, but people with different body types may have varying results. If you use this calculator, let me know how it works for you.
Tanita scales like this one boast a very high accuracy in measuring body fat. Many users report these scales are accurate within 1-2%, which is pretty impressive. However you (understandably) may not be interested in plunking $50-100 down for a scale. Neither am I at the moment.
You can also use calipers to gauge your body fat, have a water displacement test done, or head to your local gym which may have a variety of body fat calculating tools available for you. However, you don't always get what you pay for, so don't assume methods like water displacement are more accurate just because they're more expensive. In fact, some have reported wildly inaccurate results even with this method, which is often considered the gold standard of body fat measurement.
Once you know (or think you know) your body fat percentage, all you have to do is a simple calculation to figure out lean body mass:
[100 - Body Fat Percentage] x 0.01 x body weight = lean body mass
So, for me, this would be:
[100 - 28 = 72] x 0.01 x 143 = 102.96 lbs of lean body mass
So using this method, I need roughly 100 grams of protein every day. My actual intake right now tends to fall between 80-100 grams, which feels right and isn't too much of a stretch for me.
Some Parting Words on Protein
While protein is important and we all need some, don't take these numbers so seriously that they rule your life. I recently ran across a forum post where someone was freaking out (seriously) that they'd been eating 15 grams of protein less than they figured they needed each day. They were petrified that they'd lost significant amounts of lean body mass during the previous weeks! (Which, aside from being ridiculous is also downright impossible.)
The body isn't that rigid in its requirements, trust me. Like I mentioned in my Counting Calories is Pointless post, to even assume we can figure out with accuracy exactly what our body requires is pretty off base. Numbers can be useful, but they aren't the end all be all. Learn what works for your body and your lifestyle. Pay attention to your biofeedback and use a little common sense. Think of the numbers we've talked about in the last two posts as a starting place that you can tailor to fit with what works best for your body.
Remember: As important as it is to eat enough protein, it's even more important to choose the right protein. High quality dairy, eggs, legumes, seafood and meat are among the top sources. Avoid soy like the plague: it's an anti-food.