Why is strength training important for losing weight? Because a lot of people try to starve themselves into weight loss. They think it's all about controlling calories. Unfortunately, a lot of dieticians and nutritionists don't really understand strength training, and they also think that it's just about calories. Calories in, calories out. If you have a calorie deficit, you're going to lose weight, if you consume extra calories, you'll gain body fat. While that's true, it's only part of the picture. Sure, you need a calorie deficit to lose weight, but how does your body actually use calories? It's your lean body mass, that muscle mass underneath your body fat, that burns calories 24/7, allowing you to actually eat more calories without gaining weight.

Let's say you happen to be quite obese and you have a high percentage of body fat. I used to be in that situation; I know what it feels like. Underneath that body fat you actually have a very strong skeleton and strong muscles. Your body has built up those muscles in order to carry all of that extra body fat when you move your body. Just the very act of standing up, walking across a parking lot, going up a flight of stairs or lifting your arms requires more effort when you're overweight, especially if you're obese. So the heavier you are, the stronger your muscles have to be just to allow you to do basic, everyday things.

Now this can actually work to your advantage -- if you manage to keep all of that muscle mass and bone density in place while you are losing body fat, then you can maintain the high metabolism that's associated with that lean body mass even while you are dropping body fat. But if you starve yourself, you're going to lose all the muscle resources you already have. It's a mistake a lot of people make. They try to lose body fat by starving themselves, and as the body fat vanishes from their body, their muscle mass also disappears. Why would the body get rid of muscle mass? Because, frankly, it doesn't need it.

Your body adapts to the need
You see, the body is an adaptive system. It will adapt to whatever loads you place on it. So if you are a heavier person and you're carrying around body fat, then your body will adapt by creating stronger muscles to lift your body. It's almost like doing a leg press every time you get up out of the chair. If you weigh 300 lbs you're doing a 300 lb leg press, you see? Now if you were to drop 150 lbs of body fat and end up at 150 lbs, your body wouldn't need the same amount of leg muscle to lift you. It would eliminate those leg muscles through catabolic action.

While it eliminates this muscle mass, your metabolism begins to slow. Remember, it's the lean body mass that's burning calories day in and day out, even when you're doing nothing. If you reduce that muscle mass by allowing it to go away (by not challenging your muscles), then your metabolism is going to slow. A lot of people end up at a place where they've lost the body fat and they're lighter, but it's suddenly so much easier to put on body fat. They don't have the muscle mass they once did, they're not automatically burning calories, and if they overeat just a little bit, they'll start packing on the body fat again.