Lean Body Mass and Goal Weight

jmcnamar484

So I just re-joined MFP a few weeks ago and decided to get my body fat percentage done by hydrostatic water testing today. So basically I'm 175 lbs and 127.6 of that is lean mass. My Body fat % is 27.2. He said 127lbs of lean mass is pretty high especially for someone who hasn't been working out that much and asked if I was an athlete in high school or college (which I was).

Anyways, I told the man that my goal is to get to 140 or 145 isn and he told me that is not a realistic goal because I have so much muscle mass and I will likely lose muscle to get to that point and it will be hard to maintain. He told me 156 would be a better goal and would put me in a good BF % range if I kept exercising and eating right. Does this sound right? I have been 156 and wasn't so happy with the way I looked. The lowest I've even been was 130 or 135 isn which was too low for sure.

Thoughts?

3dogsrunning

My thoughts are I wouldn't worry about numbers. If you want a specific number to shoot for, maybe aim for the 155 and reassess when you get there. It doesn't have to be a final number. Maybe you will agree when you get there, maybe not.
My understanding is that when losing weight, losing LBM is inevitable. How much depends on a number of factors including what you are doing exercise wise, what you are eating, how big your deficit is, genetics, etc. Also, not all LBM is muscle mass either.

ETA - I also dont understand why he says it would be hard to maintain.

bc2ct

What kind of "man" are we talking about here? An exercise physiologist? A PT?

If you lost weight down to 140 lbs without losing muscle, you would be under 9% body fat which for a female is extremely low for a female. The fact is though that you would probably lose muscle over the course of your weight loss because the behaviors necessary for losing 35 lbs to not facilitate muscle maintenance (calorie cut, lots of low-intensity exercise, etc). So let's say you get down to 140 lbs and you have lost 15 lbs of muscle during the cut (not unrealistic, especially depending on the speed at which you want to drop the weight). Then you would be just under percent body fat (still pretty lean for a female but not extremely lean). The thing is that muscle uses energy and burns calories so at 140 lbs and 112lbs of muscle you would not be able to eat nearly as much as you would at 140 and 127lbs or, more ideally, 155 and 127 lbs of muscle). Having to consistently eat less because you have much less muscle may break your weight loss goals AND you could be at the same or a lower body fat percentage at 15 lbs heavier when that 15 lbs is of muscle).

Basal Metabolic Rate Comparisons

140 with 112 lbs of lean mass - 1545
155 with 127 lbs of lean mass - 1752

Note: These are approximately the same body fat percentages.

jmcnamar484

ok thank you to both of you.

And the man...well I don't know who he is. LOL. He just does the body fat testing at the testing center. I just assumed he knew what he was talking about since he does this all day every day.

That is a lot of information and I guess I have to take it all day by day and week by week. I have just been hearing over and over again how you don't want to lose muscle mass so it is important to lose weight slowly. I guess it is inevitable that you will lose muscle mass as you lose weight?

Thanks for the help!