Although this is changing recently, most diet books and trainers tend to only talk about weight loss and most people attempting to diet only think in terms of weight loss. I want to make a distinction between weight loss and fat loss before i put any more posts about dieting advice as i think it is very important! If you aren’t aware of the distinction between bodyweight and bodyfat (and weight loss versus fat loss), this is for you.
Weight versus fat loss: they are not the same thing
Every tissue in your body (including muscle, bodyfat, your heart, liver, spleen, kidneys, bones, water, minerals etc.) weigh something. We could (although it would hurt) take each of them out of your body, plop them on a scale and find out how much they weigh. Your total bodyweight is made up of the weight of every one of those tissues. But only some portion of your total weight is fat. This is why you may hear of researchers and some coaches divide the body into two (or more) components including fat mass (the total amount of the bodyfat you have on your body) and lean body mass (everything else).
Let’s say that we could magically know the weight of only your fat tissue. Of course, we know your total weight by throwing you on a scale. By dividing the total amount of fat into the total bodyweight, you can determine a bodyfat percentage, the percentage of your total weight that is fat. Lean athletes might only have 5-10% bodyfat, meaning that only 5-10% of their total weight is fat. So a 200 pound athlete with 10% bodyfat is carrying 20 lbs. (200 * 0.10 = 20) of bodyfat. The remaining 180 pounds (200 total pounds - 20 pounds of fat weight = 180 lbs.) is muscle, organs, bones, water, etc. that remaining 180 pounds is the lean body mass or LBM.
LBM is lean body mass, the amount of your body that is not fat.
An average male may carry from 18-23% bodyfat and an average female somewhere between 25-30% bodyfat. So a male at 180 lbs. and 20% bodyfat is carrying 36 pounds of fat and the rest of his weight (144 lbs.) is LBM. A 150 pound female at 30% bodyfat has 50 pounds of bodyfat and 100 pounds of LBM. Healthy levels of bodyfat are still up for debate but most ‘authorities’ recommend 11-18% as being optimally healthy for males and 18-25% as being optimal for females. And, yes, this means that being too lean can have its own set of health problems as well but being too lean is generally not the problem for the average person. It is important to know that even if you never achieve ‘healthy’ or 'optimal' bodyfat levels, even a small fat loss like 10% can vastly improve your health. So if you currently weigh 250 and lose even 25 lbs. and keep it off long-term, you will be healthier even if you are still above ‘optimal’ bodyfat levels.
Why is this important?
So let’s say you start a diet, reducing or changing some part of your daily food intake. Maybe you start exercising, too. After some time, you get on the scale and it says you’ve lost 10 lbs.. That’s 10 lbs. of weight. But how much of it is fat? Really you have no way of knowing with just the scale (even if it is those Tanita bodyfat scales, which attempt to estimate bodyfat percentage but don’t work very well in my opinion). You could have lost fat or muscle or just dropped a lot of water. Even a big bowel movement can cause a weight loss of a pound or two. A colonic that clears out your entire lower intestinal tract may cause a significant weight loss. The scale can’t tell you what you’ve lost, it can only tell you how much you have lost.
When you’re worrying about long-term changes, the real goal is fat loss. So cycling water weight on and off of your body (which often happens with certain dieting approaches) isn’t really moving you towards any real goal even if it makes you think you are. It may be beneficial in the short-term but it doesn’t represent true fat loss.
So we encourage you to not focus on the scales so much but to take body measurements, frequent pictures for reference and simply looking in the mirror, you will know when you are getting leaner!