This stems from reading the body fat% threads that are going around right now.

My goal weight of 140 was based on having 30% body fat at 165lbs (calculated with bioimpedence). My lean body mass, then, was about 115.5 lbs. That's almost 50lbs of fat. If I lost 25lbs of fat to reach 140, then I would have 25lbs of fat left, and 25/140 is 18% body fat.

I've been jogging, biking, and spinning to lose the weight, along with a little bit of lifting a couple times a week. At 155lbs, I used the same Omicron to measure my bf% and it was 29%. If those readings are accurate, that meant I lost 5lbs of lean body mass and 5lbs of fat. This kind of jives with my qualitative personal experience-- I don't feel any more toned at 155 than I did back when I was gaining all the weight, and my low weight was about 130.

Is anybody having an experience where their lifting is actually offsetting their muscle burn, and they are losing almost purely fat? If so, how much do you do? I just added a new lifting routine for my upper body that I hope will help slow the muscle loss, but I just don't think that determining your lean body mass and then basing your goal weight on losing *only* fat is a very effective method. It just seems inevitable that you are going to lose lean body mass because it is so hard to keep-- after the age of 20 women start naturally shedding muscle unless we actively try to stop it, so we have nature working against us.

It is hard to lose purely fat but yes using weights will help limit the muscle loss.

Lean body mass is a lot more than muscle though it is also cells/water used to support your heavier body. You should expect your lean body mass to drop as you lose weight, it is normal but again use weight training to help reduce the amount of muscle that is lost.

I don't know if there truely is a way to lose pure body fat. I have lost a lot of muscle even though I lifted and did resistance training all throughout my weightloss...I still feel quite squishy. Someone told me I should have eaten a lot more protein, because your body will eat at your muscles to compensate. I have no idea if that's true or not, seeing as I'm not a nutritionist or anything.

I have not lost one OUNCE of muscle mass, and in fact have gained over 1.5 poutnds of lean muscle mass since i began loosign weight...i HAVE however, lost 12 pounds, or almost 8% of my BF!!!

It is entirely possible...you are doing too much cardio (which tends to devour your muscles for energy in the long term, and you are not doing enough weightlifting, which BUILDS lean muscle mass, and you are prob not getting enough proteing either. Getting adequate protein will allow your musckes to buil larger when tey repair themselves.....MAKE SURE to consume a protein as SOON AS POSSIBLE after weight lifting..ideally, within 5-15 minutes of finishing...either eggs, or a proteing shake or some cheese or chicken, whatever..... and also up your meal time proteins as well...

Honestly I don't see myself cutting out cardio because I love the activities I do and I love doing them intensely. Maybe that is just something I will have to live with. I will however try to get more protein and lifting in...thanks for the inspiration!

For the most part, it's physically impossible to gain LBM while losing fat unless you are taking steroids or some other drugs. You are bound to lose some LBM when you are in a caloric deficit mode. Key is to try to minimize LBM loss relative to the fat loss. Caveat is if a person is extremely obese or a newbie to exercise in which case muscle gain while losing fat may be possible for a short time but they won't be able to maintain it for long.

I think doing some strength training is helpful in this regard.

Im sorry to have to disagree with yo KDuffer...i have never taken steroids or any supplemental growth hormone or anything, and i have been exercising vigorously---RELIGIOUSLY for over three years (in fact, training for a marathon), nor am i obese (137 at 5'4" and 20% BF--WAS 147 at 28% BF)..I lost 100% BF and NO lean Muscle mass (in fact, gained some)...all by ADDING TONS of protein, in the correct ration to carbs, and actually limiting my cardio to only 1 hour a day (or approx 6 miles running)

I would respectfully suggest body type can make a big difference too. Two people can train and eat the same and get different results.

There are ways to preserve muscle while losing weight, and even build it slowly if you're calorie partioning, eating the right foods, and lifting heavy and consistently. HOWEVER, Lean Body Mass includes more than muscle. Your blood volume is higher to support a heavier body. You hold more water in your cells and have more intracellular fluids. These changes mean that even if your muscle mass stays the same, you'll have some loss in your measured "Lean Body Mass" because your fluid volumes will go down. So if you lose 5 lbs of fat and 5 lbs of lean body mass, it doesn't mean you lost 5 lbs of muscle...you lost 5 lbs of combined muscle and fluid volume.

And bones and organs, don't forget them. They're part of your lean body mass as well They're going to stay pretty stable weight-wise of course, but a taller person will necessarily have longer bones which weigh more....

I agree with consuming protein with a light carb immediately after weight lifting. You are born with your muscle type. There is fast twitch and slow twitch. If you have more fast twitch--you have a higher propensity to be able to build muscle fast--while if you are slow twitch--you have more endurance for marathons.

it seems to me forest you are built for endurance not necessarily a muscle machine--but you can condition your body somewhat with weight lifting.