I asked a similar question but wanted to give better details. I was wondering if someone could explain how a calorie deficit causes a person to lose fat. I know a pound of fat is 3500 calories and one should create a deficit of 500 per day to lose that pound in 7 days, or 1 pound per week. And if you go over your maintenence level you gain a pound of fat, that part I get. What I dont get is how a calorie deficit causes fat loss since its a mix of different calories (carbs, fat, protein) and not directly fat.
If say my BMR is 1700 and my calories taken in for the day was 1500, and I run 1 mile to burn an additional 300 calories.
I went below my BMR by -100. (1500+300=1800, 1700-1800= -100)
Would my body then pull that extra 100 calories from fat stores to meet the 1700 BMR, thus leading to fat loss? Thanks in advance.
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The calorie is just a unit of measurement of energy. The energy source doesn’t matter.
Your body cells generally grab energy sources that are handiest, so if you have proteins, carbs and fats flowing by in the bloodstream, it’ll take those. If it doesn’t need all the energy in the blood, the protein (what isn’t used as protein for rebuilding body parts or as an energy source) and carbs will be stored as fat.
Once your body uses energy from the blood, to where it’s below a certain level in the blood, your system will take stored energy and replenish the blood supply, where it’ll be available to your cells. Now, energy is stored as fat, and that’s normally what resupplies the blood, but the body will also grab protein energy from the muscles. It’s recommended that you work out or exercise during dieting to make sure the muscles stay built up and don’t get depleted.
In your BMR question, you said you went below your BMR. The BMR is the minimal rate of calorie usage, what you use at rest. So by burning extra calories, you went above your BMR, not below it. (You intake was below it, though.)
So, yes, you’d estimate that your body would grab the extra 100 calories from your fat stores, and you’d lose a bit of weight. I say estimate, because exercise speeds up your BMR. It’s not a static number; it changes. So you can’t predict exactly what you’ll lose or gain.
You’re right, but your math is off.
If your BMR is 1700 and you ran burning another 300 cals, then you burned 2000 cals over the course of the day. You then consumed
1500 calories. So it would be 2000 – 1500 = 500 calorie deficit.
When your body’s energy needs are not me by your diet, then it turn to fat stores to make up the deficit. Fat is simply how your body stores excess calories. I think your confusion may come from a misunderstanding of how your body stores energy. Your body fat is not made up exclusively from the fat you eat. Your body converts unused energy from carbs and fat into body fat. Protein is either used to build muscle or expelled from the body.
Yea you’re pretty much right, the energy you’re body utilizing will be fat as oppose to carbs thus reducing the size of your fat cells
Your body stores all extra energy as fat. Even if you ate a completely fat-free diet, your body would store excess energy as fat.
When you burn calories, your body needs to get energy from somewhere, so it uses its stored reserves of fat. That’s how you lose fat- use up more calories (by exercising or eating less) than your body is getting. Make sure that you’re following a balanced diet plan, by exercising and eating reasonably. You won’t have the energy to exercise if you don’t eat. There are many places where you can find the number of calories that your body needs to maintain its weight every day. Keep your calorie intake close to that, but exercise, in order to lose weight and stay healthy.