Hi all! I'm new here, and I haven't been on a diet in about ten years, but my weight's been gradually creeping up, and I think it's time I got in shape.

However, I'm running into difficulties selecting a goal weight. I picked 150 pounds first, because 100 pounds is a nice round number to lose, and it would put me at the top of my healthy BMI range. I started going to the gym, doing weights and the C25K program, and counting calories.

But yesterday I went to Boots and weighed myself and took my bodyfat reading. It said I weighed 242 pounds, and 107 of that was fat. That means everything but fat is 135. However, obviously everyone needs some bodyfat! If I went down to 150, I'd be 10% bodyfat, which is way too low. Apparently 20% is an excellent level of bodyfat for a woman. That means I'd need to be 170 pounds to be 20% bodyfat with my current everything-but-fat weight. And that's assuming I don't gain any muscle! And 170 is in the middle of the overweight range for my height.

I didn't think I was that muscular. And I understand there's a margin of error on the machines. But I don't want to set a goal weight I can't achieve without losing muscle - that won't make me healthier. Can anyone advise on what a sensible goal would be?

Yeah, it really doesn't work that way, wish it did because at 5'6" 150 10% BF you'd be rockin'! Not that you won't be rockin at 5'6" 150 anyway.

When we lose weight we don't just lose fat, we lose water, muscle and I'm sure some other stuff. My stats are similar to yours, I don't know what my starting BF was but at 140 it was 20% and I'm a very fit runner, strength trainer and yogi. But I like my indulgences and I don't have what it takes to get my BF any lower so it is what it is. I've recently gained about 10 lbs, I won't go into the gory details, but I think my BF is closer to 23-25% now.

So anyway, don't get to caught up in all that, just do what you need to do to lose and once you reach goal, you'll know it.

Haha yes, I'm not expecting to get to 10% bodyfat! But I want to minimise the amount of muscle I lose, I'm doing resistance training and eating plenty of protein. I'm just trying to work out what's a sensible weight for me, as I don't want to aim towards something that isn't right for me.

If 150 is the top of your healthy range, it sounds like a perfectly reasonable goal to me. You might consider picking smaller milestone goals (like every 20 lbs) to assess the changes and adjust your final goal as needed.

As the previous post mentioned, it's not a simple formula. You can't prevent loss of some nonfat mass (bone, muscle) because it simply will not be needed to support a smaller body. And yes, those BF measuring devices are notoriously inaccurate, so don't plan your life around one.