100 lb. Club - Body fat calcs. does this work?




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ubergirl
01-21-2010, 01:59 PM
So, I've been puzzling about something, and I'm wondering if this works.

Right now, I'm 5'8", I weigh 225, and according to my scale, my body fat percentage is about 44% or about 100 pounds of fat....


So, according to the numbers I've seen, for women up to 31% body fat is "acceptable" and above that is obese.

So to get to "acceptable" I'd have to lose about 30 of fat , which would make me weigh 195-- which is a BMI of 29 for me. But to get to "fitness" I'd have to lose about 45 lbs of fat, down to 180, which would be a BMI of 26....

So, that doesn't seem right? Presumable, if I had 24% body fat, or fitness level, I'd weigh less than 180. Is it because I would lose some muscle mass as I got smaller, because you need more muscle to support the fat?

Or does it mean that at 180 I could have a BF % of 24%?


BeachBreeze2010
01-21-2010, 02:13 PM
BMI really doesn't work hand in hand with body fat %. An example - years ago, I weighed 130lbs and had 13% body fat. While I was exceptionally lean, my BMI said I was almost overweight which of course is ridiculous. At 135lbs, I was 16% body fat and was overweight by the BMI standards. Personally, I take a lot more from the body fat calcs because they are ultimately the goal, not a particular weight on a scale. It's just hard for us at a higher weight to use body fat % because calculating it accurately is almost impossible with calipers. If you have a scale or some other more expensive instrument, then great!

ubergirl
01-21-2010, 02:40 PM
BMI really doesn't work hand in hand with body fat %. An example - years ago, I weighed 130lbs and had 13% body fat. While I was exceptionally lean, my BMI said I was almost overweight which of course is ridiculous. At 135lbs, I was 16% body fat and was overweight by the BMI standards. Personally, I take a lot more from the body fat calcs because they are ultimately the goal, not a particular weight on a scale. It's just hard for us at a higher weight to use body fat % because calculating it accurately is almost impossible with calipers. If you have a scale or some other more expensive instrument, then great!

I have a scale.


Meg
01-21-2010, 02:46 PM
Body fat percent sure can get confusing! I'm getting some different numbers when I look at your body fat. See if this makes sense?

If your BF% is 44% and you weigh 225, it means that you have about 125 pounds of LBM and 100 pounds of fat.

If you weighed 195 and were 31% fat, your LBM would be 135 pounds and you would have 60 pounds of fat (195 x .31 = 60). If you weighed 180 pounds and were 24% fat, your LBM would be 137 pounds and you would have 43 pounds of fat (180 x 24 = 43). In both these scenarios, your LBM would have to increase by either 10 or 12 pounds, from 125 to 135/137 pounds. But in reality, it's unlikely that you could add 10-12 pounds of muscle while losing 48 pounds of fat, even with some pretty rigorous weight training.

So let's say that your LBM stays at 125 -- which is fairly optimistic scenario -- then at about 177 pounds you would be at 31% BF (177 x .31 = 52 pounds of fat). Your BF% would be 24% when you would weighed about 152 pounds (152 x.24 = 36.5). Does that make more sense to you?

The truth of the matter is that we don't lose 100% fat as we lose weight. Lean Body Mass is much more than muscle -- it's everything in our bodies that isn't fat, so it's hair, skin, bones, blood, and water. Smaller bodies don't need the same volumes of blood and water that larger bodies do and don't need the same amount of muscle that was needed to cart around an obese body. Some LBM is almost inevitably lost when we lose fat. Our goal is to minimize it's loss and especially to be sure that we don't lose muscle.

Right now, it's very hard to predict what you might weigh at certain body fat percentages. It's a situation that will change with every ten pounds that you go down on the scale. The best thing to do it to monitor the situation and keep on lifting weights to sustain and build your muscle mass!

ubergirl
01-21-2010, 03:10 PM
Body fat percent sure can get confusing! I'm getting some different numbers when I look at your body fat. See if this makes sense?

If your BF% is 44% and you weigh 225, it means that you have about 125 pounds of LBM and 100 pounds of fat.

If you weighed 195 and were 31% fat, your LBM would be 135 pounds and you would have 60 pounds of fat (195 x .31 = 60). If you weighed 180 pounds and were 24% fat, your LBM would be 137 pounds and you would have 43 pounds of fat (180 x 24 = 43). In both these scenarios, your LBM would have to increase by either 10 or 12 pounds, from 125 to 135/137 pounds. But in reality, it's unlikely that you could add 10-12 pounds of muscle while losing 48 pounds of fat, even with some pretty rigorous weight training.

So let's say that your LBM stays at 125 -- which is fairly optimistic scenario -- then at about 177 pounds you would be at 31% BF (177 x .31 = 52 pounds of fat). Your BF% would be 24% when you would weighed about 152 pounds (152 x.24 = 36.5). Does that make more sense to you?

The truth of the matter is that we don't lose 100% fat as we lose weight. Lean Body Mass is much more than muscle -- it's everything in our bodies that isn't fat, so it's hair, skin, bones, blood, and water. Smaller bodies don't need the same volumes of blood and water that larger bodies do and don't need the same amount of muscle that was needed to cart around an obese body. Some LBM is almost inevitably lost when we lose fat. Our goal is to minimize it's loss and especially to be sure that we don't lose muscle.

Right now, it's very hard to predict what you might weigh at certain body fat percentages. It's a situation that will change with every ten pounds that you go down on the scale. The best thing to do it to monitor the situation and keep on lifting weights to sustain and build your muscle mass!

Meg, thank you so much! Math has never really been my strong point.

I haven't been fit or lean in a really long time, but when I was in sports in college, I used to weigh between 150 and 160 so I didn't figure that I'd be at my fighting weight at 180....

I kinda still don't get why having more muscle mass helps... and why is staying at 125 lbs of LBF a "fairly optimistic scenario?"

Is that because my LBF is probably higher than average because of the extra muscle, skin, water and blood I'm toting around due to the 100 pounds of fat?

And how is "acceptable" defined, anyway-- does it relate to the obese, overweight, healthy BMI categories?

And last of all, does that mean that for now, my goal weight of 175 seems relatively realistic, with the option of tweaking later on as needed?

nelie
01-21-2010, 03:35 PM
As Meg said, lean body mass is a lot more than muscle. Your body produces extra tissues, blood, etc when you are overweight so as you lose weight, your body needs less of those. Also, you do tend to lose some muscle when you lose weight. Even if you are doing extremely heavy weight lifting, maintaining your lean body mass would be very difficult.

Overall, I'd say stick to 175 for now and when you get there, you can re-evaluate.

Meg
01-21-2010, 03:39 PM
I think your goal weight of 175 sounds perfect for now. :) I'm four inches shorter than you are and my first goal was 160, so yours and mine are pretty comparable.

When you get to 175, then you can assess factors like how you feel, the size you're wearing, your body fat percentage, health indicators like blood pressure, and most importantly, how sustainable that weight feels to you. You might decide to maintain there for a while or you might set a new goal, but for now, 175 sounds ideal.

The body fat ranges aren't in any way related to BMI. They're two totally different animals. BMI is strictly a height-weight correlation and is the same for everyone. Body fat percent measures your body composition and is unique to you. My personal belief is that body composition is a far better indicator of health and fitness than is BMI.

More muscle is always better! Your LBM of 125 pounds is on the high side for a woman, probably because you've done so much weight bearing exercise just in the course of everyday living! True, you also have the skin, blood, water etc necessary to sustain 225 pounds, but you also have more muscle than most normal-weight women. It is very much to your advantage because muscle is the calorie burner in our bodies. The more muscle you have, the more calories you can eat to maintain your weight (or to lose). And you will look so much better when you get to your goal than someone with less muscle.

The reason I said that it would be fairly optimistic to assume your LBM stays consistently at 125 for the entirety of your weight loss is that usually some LBM is lost along with fat. We just try to minimize the LBM loss and maximize the fat loss by supporting our LBM and muscle mass with good nutrition (lots of protein) and weight training. You may end up with an LBM around 115 - 120 pounds, but it's very hard to say at this point. So let's not even speculate about it!

The one thing that I can tell you about your goal weight is that you'll probably know when you're reach there. You'll be feeling fit and athletic, you'll be thrilled with clothes shopping, your doctor will think that you're awesome, and most importantly, you'll be living a lifestyle that you're certain that you can comfortably sustain for the rest of your life. You'll feel comfortable in your skin and you'll feel like you've stripped away all the layers and this is the "real you". You'll just feel that a particular weight is right for you. I know from all of your posts that you're sensible and thoughtful and you won't go chasing after low scale numbers just for the sake of reaching a number. Trust your instincts. :)

Reading your recent posts just gives me such a thrill -- it seems like you've just caught on fire lately! Not with weight loss, necessarily, but with your whole attitude. There's no doubt in my mind that you're going all the way!! :carrot:

ubergirl
01-21-2010, 11:25 PM
Reading your recent posts just gives me such a thrill -- it seems like you've just caught on fire lately! Not with weight loss, necessarily, but with your whole attitude. There's no doubt in my mind that you're going all the way!! :carrot:

Gosh, that is JUST THE NICEST thing to say!!!

It's true that I am starting to feel really and truly DIFFERENT.

And I have NO intention of EVER going back to the place of misery that I allowed myself to live in for way too long!