What is Lean Body Mass exactly?

yogicarl

I just want a consensus on what folks calculate to be Lean Body Mass so I can estimate my protein needs more accurately and the answers may help anyone else who may be cloudy on this.

Most "ideal weight" charts say my ideal weight is 140lbs (within a range) so I take 25% off this figure because some of that ideal weight is essential fat and skeleton, which do not require protein for maintenance.

So my ideal LBM is 140 less 25%; equals 105lbs.

I am eating protein at 0.8g per 1lb of LBM so 0.8g x 105 equals 84g, so I calculate my minimum protein needs to be around 84g per day.

The reason I raise this is because I was calculating my protein using my ideal total weight until someone pointed out that total weight includes mass which does not require protein, so a rough deduction for this would be ideal weight minus 25%.

Am I right? Have I burned anyone's brains out yet?

SideSteel

I believe LBM is typically measured as "the stuff that isn't fat".

But that being said, there's several variables that go into calculating protein needs. Age (protein utilization can decrease with age) caloric intake (protein needs go up during caloric restriction vs caloric excess), leanness, training, etc.

Then you also have to consider practical metrics like dietary preferences/etc. Just for example I could see a scenario where someone sets their protein intake to X, which causes their carbohydrate intake to drop to Y, and they have gym performance issues due to their carb intake. This would be a rough example where it could be better to reduce protein despite what the calculator or method told you to eat.

Finally, methods using "total weight" tend to cite a lower figure per lb or per kg then methods using LBM. When you compare these two, they tend to be reasonably close to each other in most examples (certainly not all). As far as I've looked anyway, it would appear that the majority of research looks at protein needs in terms of total body weight and not in terms of LBM.

I don't think I would use your "ideal weight" based off of some chart, followed by a rather generic figure to estimate what your LBM would be at that weight, followed by taking .8g/lbm of that estimation to establish your protein needs. That just seems to me like it has the potential to be off rather significantly. If you are going to use LBM for protein needs, you should figure out what your current LBM is, not what your LBM might be when you're done losing weight.

yogicarl

Thanks SideSteel. I can see a good argument for calculating on the side of protein in excess of need, to a reasonable amount, compared to protein deficit; especially when eating in a calorie deficit.

I'll have a another look at my macros with the above in mind.

neandermagnon

your skeleton doesn't need protein for maintenance....? not sure about that... bone doesn't just sit there doing nothing, it's a dynamic tissue that's constantly adapting to the demands you put on it, which is why bone density increases with weight bearing exercise. It's also full of marrow which plays a major role in the production of blood cells and is an essential part of your immune system. I highly doubt that your bones don't require protein. They're very metabolically active, not just a support structure for your body and muscles.

yogicarl

That's a good point neandermagnon.

I've upped my daily Protein target from 84 to 112g, which equates to 0.8g x 140 total ideal weight (with a view to reassessing when I get there.

I am 20lbs fat excess at present and have been 140 before at my ideal physique.