What happens to body fat when you lose weight? Does it leave your body when you sweat, pee, or breathe? Yes, yes, and yes are the right answers.
How does this even happen? Endocrinologist Bartolome Burguera, MD, PhD, says that it helps to know that our bodies are made to store extra energy in fat cells.
If you have extra weight, it means you’re taking in more energy than you’re using. This is measured in calories, which are units of energy.
Dr. Burguera says that the extra energy is stored as triglycerides in the fat cells all over your body. Glycogen is a form of energy that is stored in small amounts in your liver and muscles.
How does your body use energy? More than you might think:
When you’re at rest, your heart needs energy to keep pumping, your lungs need energy to breathe, and your brain needs energy to think. (Your basal metabolism is that.)
When you do something: Whether you’re just getting out of a chair or running a marathon, your muscles need energy.
When you eat, your body needs energy to break down and store the food.
When you diet, what happens to your body fat:
When you’re on a diet, you eat less than your body needs. Because of this lack of energy, your body pulls energy from its fat stores.
Your body has to get rid of fat through a complicated series of metabolic pathways.
When your body breaks down fat, it gives off:
As water, when you sweat and through your kidneys (when you urinate).
As CO2 comes out of your lungs (when you breathe out).
“At the same time, breaking down fat releases energy that can be used for biological functions and physical activity,” he says. “It also makes heat, which helps keep the body’s temperature steady.”
What happens to the fat on your body when you work out:
First, your muscles use the glycogen they have stored as fuel. Dr. Burguera says that after 30 to 60 minutes of aerobic exercise, your body starts to burn mostly fat. (This takes about an hour if you work out moderately.)
Cardio should be done at least twice or three times a week for at least 30 minutes each time.
They also say that you should lift weights and do resistance training. Putting on more muscle might help you burn more calories and speed up your metabolism.
Exercise also makes you breathe faster, so when you work out, more CO2 leaves your body.
About working out and losing weight :
Dr. Burguera says that exercise is the best way to lose weight and keep it off.
But the number on your scale may not move right away, so be patient.
Some people lose weight when they exercise, while others keep the same weight, and a few may even gain a few pounds.
“However, most people who lose weight and keep it off are physically active for up to an hour a day,” he says. “It is recommended that you do some kind of exercise three times a week.”