Locations:
Search IconSearch

Where Does Body Fat Go When You Lose Weight?

What happens when you diet and exercise

Fat cells in body

What happens to body fat when you shed pounds — do you sweat it out, pee it out or breathe it out? The answer is yes, yes and yes.

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

How on earth does this happen? “It helps to understand that our bodies are designed to store excess energy in fat cells,” says endocrinologist Bartolome Burguera, MD, PhD.

If you have overweight, it means you’re taking in more energy (calories are units of energy) than you’re using.

“The extra energy is stored in adipose tissue all around your body in the form of triglycerides,” says Dr. Burguera. Smaller amounts of energy are stored in your liver and muscles as glycogen.

How does your body use energy? In more ways than you’d think:

  • When you’re resting. Your heart needs energy to pump, your lungs to breathe and your brain to think. (That’s your basal metabolism.)
  • When you’re active. Your muscles need energy whether you’re only getting up from a chair or running a marathon.
  • When you’re eating. Your digestive system needs energy to break down and store food.

What happens to body fat when you diet?

When you diet, you take in fewer calories than your body needs. Because of this deficit, your body turns to fat reserves for energy.

Your body must dispose of fat deposits through a series of complicated metabolic pathways.

The byproducts of fat metabolism leave your body:

  • As water, through your skin (when you sweat) and your kidneys (when you urinate).
  • As carbon dioxide (CO2), through your lungs (when you breathe out).

Advertisement

“Meanwhile, fat breakdown liberates energy for biological functions and physical activity,” Dr. Burguera says. “It also generates heat, which keeps body temperatures normal.”

What happens to body fat when you exercise?

Your muscles first burn through stored glycogen for energy. “After about 30 to 60 minutes of aerobic exercise, your body starts burning mainly fat,” he explains. (If you’re exercising moderately, this takes about an hour.)

Experts recommend at least 30 minutes of cardio two to three times a week.

They also recommend weightlifting and resistance training. Increasing muscle mass may help you burn more calories and raise your basic metabolic rate.

Exercise also increases your respiratory rate, so more CO2 leaves your body when you work out.

About exercise and weight loss

Exercise is key to weight loss and to maintaining that weight loss,” states Dr. Burguera.

But it may take time to move the number on your scale, so be patient.

Everyone’s response to exercise varies: Some people lose weight, others maintain it and a few may even gain a few pounds.

“Generally, however, people who successfully lose weight and keep it off tend to be physically active — up to an hour per day,” Dr. Burguera adds. “Engaging in some form of exercise three times per week is highly recommended.”

If you’re unsure how to add fitness into your daily routine or have questions about diet and a weight that’s healthy for you, it’s always best to reach out to a healthcare provider or dietitian first.

Advertisement

Learn more about our editorial process.

Related Articles

Partners lying on bed playing with their toddler
November 19, 2024/Men's Health
What’s a Dad Bod? And Is It Healthy?

Weight gain is natural as we age — but it can be cause for concern

Smiling person with double chin
August 15, 2024/Skin Care & Beauty
How Do I Get Rid of My Pesky Double Chin?

Seeing double (chins) when taking selfies? From exercises to surgery, you can reduce or eliminate chin fat, but there’s no overnight solution

female sitting meditating, eyes closed
March 19, 2024/Weight Loss
14 Ways To Lose Belly Fat

Losing belly fat can reduce your risk for chronic health conditions — try focusing on a diet high in lean protein, exercising regularly, reducing stress and getting quality ZZZs

Close-up illustration of adipose tissue
February 22, 2021/Diabetes & Endocrinology
Do You Know The Color of Body Fat?

Discover why one kind of fat can be fatal

woman performing sit ups
December 9, 2020/Weight Loss
Will Sit-ups Burn Off Your Belly Fat?

The short answer from a medical weight management expert

Woman stretching before going on a walk with her husband
January 7, 2019/Weight Loss
What’s the Best Way to Lose Body Fat (and Keep It Off)?

It helps to take a long-range view

Bowl of oatmeal, bananas, blackberries and nuts, with milk, dumbbells and measuring tape on table
April 28, 2025/Exercise & Fitness
What Athletes Need To Know About Sports Nutrition

Having a well-rounded, healthy nutrition plan is just as important as staying consistent with your exercise routine

Person paused on pedestrian bridge, stretching their quads
April 28, 2025/Exercise & Fitness
5 Easy Exercises and Stretches To Help With Flexibility

Exercising and stretching your lower back, hamstrings, hips and quads can greatly improve your physical well-being

Trending Topics

Person in bed sleeping on their side, covers off
Breathing Problems? Try These Sleep Positions

If you’re feeling short of breath, sleep can be tough — propping yourself up or sleeping on your side may help

A couple looking at skyline, with one person slightly behind the other, head bent down
What Is Anxious Attachment Style — and Do You Have It?

If you fear the unknown or find yourself needing reassurance often, you may identify with this attachment style

Glasses and bottle of yellow-colored prebiotic soda, with mint, lemon and ginger garnish
Are Prebiotic Sodas Good for You?

If you’re looking to boost your gut health, it’s better to get fiber from whole foods

Ad