Help Me Understand the Target Weight Math

February 5, 2008 · 9 comments

I’ve been thinking about my goals lately. In particular, the end game. If I can get off this darned plateau, what is the weight range I’m going to settle in? At this point, based on my own history from when I was younger, I chose 185 pounds as my target weight. That’s way out there, right now my next goal of 259 seems like an eternity. But unless I learn otherwise, I think it should be doable.

But I started to do the math on this based on my current body fat percentage, and something isn’t adding up for me. Take my last posted results from last Sunday, where I weighed in at 263 pounds with a body fat percentage, according to my Omron digital scale, of 30.4%.

So what that tells me, I think, is that my body is currently made up of about 80 pounds of fat. Which leaves 183 pounds of good stuff like bones and muscle. Now, you have to have some fat and it looks like from my searching that the numbers range from about 6-10% for athletes and around 15-20% for a normal, fit guy. So let’s assume I can somehow work my way down to a body fat percentage of 15%.

In order to keep the 183 pounds of good stuff, I would need to weigh 215 pounds to have a body fat percentage of 15%. My goal weight of 185 would be unattainable.

Clearly, something has to be wrong here. I am guessing it is my assumption that I will be keeping the 183 pounds of current good stuff. But in order to see my goal weight of 185 pounds with a body fat percentage of 15% that would mean at that point I should have 28 pounds of fat and 157 pounds of good stuff.

So what happened to that 26 pounds of bones, muscle, brains, and whatever else is in there?

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{ 9 comments }

AndrewE February 5, 2008 at 7:16 pm: Don’t forget that the good stuff is mainly water…
TB-Milwaukee February 5, 2008 at 9:01 pm: Your end goal sounds doable. Don’t focus on it too much. If you focus on the end result, you’ll get down on yourself as it seems so far away. Those mini goals are so much more acheivable and mean so much more.
kyle February 5, 2008 at 11:14 pm: Also, those scales can be way off. I measured myself on one of those scales and it said I had 22% body fat, then like a week later went to the gym and got measured with the pinchers and they came up with 31% body fat. That’s a pretty big discrepancy.
cardiogirl February 6, 2008 at 9:09 am: Dude, this is way, way too much math for me this early in the morning. I would not trust the scales for the body fat measurement. And I would not be too concerned about the body fat.

I would continue to focus, as you have been, on diet and exercise. As you know, muscle weighs more than fat and you might look crazy skinny, sinewy at 185 lbs. if you are very muscular.

You may find that at 200 lbs., comprised mostly of muscle, you look better, visually, than you would at 185 lbs.

But the math is weird, and I don’t get it either.
Sarah February 6, 2008 at 3:01 pm: Ok I’m a little familiar with this so here’s what I know:

1. The fat you are going to lose actually contains some water that isn’t counted in the fat content measurement, so this is ‘good stuff’ you will automatically lose when you lose the fat.

2. There is no such thing as ONLY losing fat. Whenever you lose mass, it will be some combination of fat, water and lean muscle mass. This is normal. Whenever you exercise (or lift the remote, walk to the bathroom, whatever), you are burning calories. The ratio of the calories burnt in terms of fat:muscle differs depending on your metabolic rate/heart rate at the moment. In actuality, the only time of the day when your fat burn v.s. muscle burn is 100% : 0% is when you are sleeping. Other than that, you’re always losing muscle when you lose fat, which is why weight training is so important when you’re on a diet.

So essentially, yes, if you want to get to 185 lbs, you are going to lose muscle mass.

Hope this helps!
john - from fat to fit February 7, 2008 at 10:46 pm: Water. duh.
JanB February 16, 2008 at 7:14 pm: I think that you need to remember too, that everyone has a different build. I am finding out that my target weight is probably not something I am going to be able to attain, but I am also finding out that I actually need a little more fat in some areas and I wish I could just transplant it! I would love to take my belly jelly and move some of it to my hands and feet to warm them up and some to my butt to cushion my tailbone!
HJP October 31, 2008 at 12:53 pm: To try to lose 80 lbs shouldn’t be the goal. Turning body fat into muscle should be the goal. People need to realize that body fat is turned into muscle through diet/exercise and muscle weighs more than fat. Scales do not determine fitness.

Well, that is technically true - but trust me, I need to lose weight and I use the scale to measure against that. Yes as I get fitter the scale will mean less, but right now it is key part of my measurement process (as is taking waist measurements).
Edward January 22, 2009 at 4:32 pm: What you were missing from your equation was the fact that you are going to be “gaining weight” or rather mass, lean muscle mass. You probably need to put on about 6-7 lbs of lean muscle mass and drop about 60 lbs of fat to get down to about a 10-12% body fat range… Always remember muscle burns more calories than fat. 6-7 lbs of lean muscle gained… doesnt sound so hard but it could take you 3-4 weeks just to put on 1 lb of lean muscle… its achievable though. You probably figured all this out already considering your post was from a year ago… but just wanted to give you a heads-up!