Lean Body Mass and New Goals

Last Wednesday, when I signed up for the gym, the manager asked me what my goals were. Of course I said to lose weight, but also to build muscle tone. When he asked how much I wanted to lose I smiled and said at least 29, but technically I need to lose at least 50 so I wasn’t sure yet. He kind of laughed – not in a bad way, but he pointed out that those were very different numbers. And honestly he is right and that is why I have such a hard time picking a goal.

I also mentioned a few times that my doc set my goal at a 29.9 BMI (180lbs). I lowered it to 175 so that I had some breathing room from the obesity label. But according to the BMI scale I need to be 150 to be labeled normal. Most doctors I have had in my life (including my current NP) have always told me that I have a larger frame and that the BMI scale doesn’t necessarily predict what is healthy for me. In fact, my NP said if I get to my “ideal” weight (some medical formula puts it at 125) she would probably label me anorexic. I think I would be dead.

In preparation for my appointment with my new personal trainer (personal torturer) I ran through all my numbers in my spreadsheets.  One number that I have been tracking, but not paying a ton of attention to is  my body fat. While doing this I had an epiphany. The BMI scale may be skewed for larger framed people, but body fat isn’t. What is considered a healthy percentage of body fat for a small framed woman is also considered healthy for a larger framed woman (with some variation for age).

Once I figured that out, I researched what a healthy body fat percentage was. That isn’t as easy as it sounds. There are many different charts out there saying different things, but I did find one chart that seemed to be repeated quite a bit. I am not sure where it originated from, but it is listed on the American Council on Exercise website.

So now that I had my research done I need to find out what it would take to get me to get to each classification. To do that I estimated my Lean Body Mass (LBM) – muscle, bones, organs, etc… (Body Weight X (1- Body Fat %). According to this, I currently have 126.48 pounds of LBM. That would leave me with 77.52 pounds of body fat (yuck!). Now ideally when you lose weight you want to lose body fat not LBM. So if I want to get under 32% body fat (considered Acceptable) then I need to lose 18 pounds of body fat. To get in the Fitness range (under 25%) I would need to lose 35 pounds of body fat.

(What my goal would be like at a steady LBM - Notice that the lowest value (Fit) is still 10lbs over the "normal" BMI range)

That sounds so great! I mean that would mean at 183 I would have an acceptable body fat and at 168 I would be considered Fit. That is 18 pounds heavier than what the BMI scale says is normal! The only twist is that to just lose body fat is really hard to do. One reason is because you are carrying less weight and thus you need less muscle. It is one of the reasons why our docs stress the protein part - it doesn’t just help with keeping us full and keeping our hair in place :)

From what I can gather losing 25% is considered normal without a comprehensive workout schedule (including cardio, strength training, and of course an appropriate fat diet). That means for every 3 pounds of fat you also lose 1 pound of muscle. In the last 10 weeks, I have lost about 15% of my weight through LBM or almost 1 pound of muscle for every 6 pounds of fat. So even without the strength training I have been doing better than average. GREAT!!! Now that I have added weight training I am hoping to continue this or do even better.

So with this in mind, I did my calculations again. If I do really bad and 25% of my weight lost is LBM then 175 would put me in the acceptable range and 148 would be considered fit. If I continue my trend of 15% then 180 would be acceptable and 158 would be fit. I love these numbers!!! They seem to “prove” that the BMI scale isn’t right for me and that my NP might be right when she says that even 150 could be too low. That makes me feel SOOOOO much better about my goals.

(Estimates of what 15% LBM would look like.)

Ok so in the end what does this really mean? Basically, my goal will be set by my body fat %. I am aiming for a short term goal of 30% body fat, a final goal of 27% body fat, and a stretch goal of 24% body fat. The actual pounds are still up in the air and will be determined by how good I am in keeping my LBM up.

 

However today I am committing to a couple pound related goals. I am setting a minimum goal of 175 and maximum goal of 155 (5 pounds over a normal BMI). If I do hit 155 and feel like going lower I am going to take a hard look at my body fat. If it is over 24% then I am going to focus on building my LBM (without losing weight!). If I am already at 24% fat then I will re-evaluate my goal and set it lower, but that decision can’t be made until I hit that point. I can’t wait to have that discussion with myself ;)