I love words. I'm a freak for crossword puzzles, own boxes of books, love etymology, have a pretty extensive vocabulary, am a stickler for spelling and grammar (in other people, of course), hope to someday own the entire 20-volume set of the Oxford English Dictionary. Love words.
Sometimes, though, my love of words gets in my way. Sometimes, things become just words to me, and don't seem to be attached to anything practical. Words like, "body fat percentage", for instance.
I got my body fat percentage taken at 24-hour fitness the other day, and I even posted here that it was between 30 and 33%. But it really didn't mean anything to me...sure, it was something I was curious about, and a number I figured I should know, and one that I wanted to bring down as time went on. However, my brain just never made the connection that "body fat percentage" could be used for anything. It was just another measurement to take and file.
I was lurking over at the Donut forums yesterday, and someone (Shiz?) posted something about body fat percentages and calculating your goals from that. I read that and the connection suddenly clicked into place. "Holy shit! I can CALCULATE my goal weight!" (I love math, too. I'm an equal-opportunity nerd.)
So I set about doing just that.
First, I had to figure out how much fat 33% of 177 lbs. was--58.4 lbs.
Subtract that from 177 to get lean body mass--118.6 lbs.
Then I looked up what my goal body fat percentage should be, which was anywhere from 18-25%. I chose 20%, because it would make the math easier.
I started to run the numbers (118.6 =.80x). If my lean body mass stayed exactly the same, then my goal weight should be 148.2. 148.2? That didn't seem right to me, since that is very near the top of the healthy BMI range for my height.
I started to see the problem with that formula--as much as I'd like all my weight loss to be fat and keep all my LBM or build more, that just doesn't happen. There's always going to be some LBM loss, so how much is normal?
I googled for a while, and then decided to ask my fallback source--Rob. He spent two years researching weight loss and muscle-building, lost about 35 lbs. and increased his strength considerably. (Then he took a couple years off, and is back to square one, essentially.) He's a student in everything, so he's read about 50 books on strength training, weight loss, etc. He would know the answer to this question. So I asked him on the way back from the gym last night.
"So, when losing weight, what's the normal ratio of fat to lean mass lost? [and then a bunch of stuff about calculating weight loss goals and most of what I've already written here]"
"Working out and eating well, 75% fat, 25% lean is a good weight loss. With some supplements, you can change that ratio, but those things aren't really all that healthy."
75%. Works for me. So what was the formula? I should mention now that even though I love math, I'm not particularly good at puzzling through things on my own. Give me a stock formula, and I'm all over plugging things into it. Making up my own formula, I tend to do the equivalent of entering a house by breaking a window at the back and crawling through it, rather than just walking through the unlocked front door. In other words, I take a lot of probably-unnecessary steps.
I started with my current goal--135. To get to 135 from 177, I'll have to lose 42 lbs. With a 75/25 ratio, that would be 31.5 lbs. fat, 10.5 lbs. lean. This brings me to 108.1 lean, 26.9 fat. 26.9 is what percentage of 135? 19.9%.
Woohoo! Looks like I had the right goal all along. Now, if I could just get the 40 minutes back that I spent calculating all of this, we'd be cool. :)
(Note: This calculation makes the assumption that I'm not going to gain any lean body mass, which may or may not be true. However, if I had tried to factor that into my little "equation" also, my head might have exploded. This is close enough.)
Posted by Joy at June 30, 2004 11:39 AM