# Will building muscle eventually take over the space of fat?

I’m trying to lose fat and get in shape. I’ve been lifting weights a lot and I want to know if I just focus on building muscle will I lose my fat at the same time?

### 1 Answer

- 3 months agoFavourite answer
Fat is nothing more than energy storage, like having full gas cans in the trunk of your car. On the average, it takes 1 calorie per kilogram of lean mass per hour to maintain that lean mass, and about 0.4 calories per kilogram of fat per hour to maintain the fat (i.e., stay alive). The only way you'll lose fat is if you have a calorie deficit. If you eat more food because you're working out more, then you won't lose the weight.

So let's say you weigh 100 kg and you have a BMI of 25%. That means you have 75 kg of lean mass (bones, muscle, water, etc... is all considered lean for the purposes of these calculations) and 25 kg of fat. If you wanted to have a BMI of 15% and you didn't add any muscle, then how much fat should you lose?

0.15 = (25 - x) / (100 - x)

0.15 * (100 - x) = 25 - x

15 - 0.15 * x = 25 - x

x - 0.15 * x = 10

0.85 * x = 10

85x = 1000

17x = 200

x = 200 / 17

204/17 = 12, roughly

So if you lost 12kg of fat and gained no muscle, you'd have (for this example) a BMI of 15%. How many calories is that? 1 gram of fat = 9 calories. 1 gram of protein = 4 calories. 1 gram of carbohydrates = 4 calories.

12 kg * 1000 g/kg * 9 calories/g = 108000 calories.

You'd need to lose 108000 calories.

Now, we need to find your base metabolic rate

75 kg lean mass * 1 calorie/(hr * kg lean mass) * 24 hours/day + F kg fat * 0.4 calorie/(hr * kg fat) * 24 hours/day =>

75 * 24 calories/day + 9.6 * F calories/day =>

1800 + 9.6F calories/day

You started with 25 kg of fat and ended with 13 kg, so let's say you want to shoot to maintain that 13kg figure.

1800 + 9.6 * 13 calories/day =>

1800 + 117 + 7.8 calories/day =>

1924.8 calories/day =>

1900 calories/day

Right now, you'd have 25 kg of fat

1800 + 9.6 * 25 =>

1800 + 240 =>

2040

If you consumed 1900 calories per day, you'd burn, on average, 70 calories per day just by being alive (because (2040 - 1900) / 2 = 140/2 = 70, and we're just looking at the average here).

108000 / 70 =>

10800 / 7 =>

10010 / 7 + 770/7 + 20/7 =>

1430 + 110 + 3 =>

1543

1543 days, just by dieting alone, to lose that 13 kg.

Keep in mind, this is the base metabolic rate. This is just what it takes to keep you alive. Anything extra you do will go a long way.

If you hopped on a bike and burned 400 calories extra per day and threw in some weight training to take off another 200 calories per day, then even if you ate 1900 calories per day, you'd lose 670 calories per day on the average

108000 / 670 =>

10800 / 67 =>

32400 / 201 =>

32400 / 200 =>

324 / 2 =>

162

Minding your intake, hopping on the bike, taking the stairs, doing some bench presses, and suddenly you've knocked almost 90% off of the time required to hit your target weight.

And the more muscle mass you add, the more lean mass you have and the more calories you'll burn. Every kilogram of muscle you add is another 24 calories burned per day.