Here’s Where Fat Goes When You Lose Weight

middle aged man weighing himself
How Does Fat Leave the Body? Jose Luis Pelaez Inc - Getty Images

POV: YOU'VE BEEN focusing heavily on your nutrition and exercise lately, and have lost a bit of weight. You put on an old pair of jeans you haven't worn in a while, and you note the extra space where your body ends and the waistband begins. They're too big—a subtle trophy of your success. But the loosened fit arises a strange question: Where does that fat go when you lose it?

You think back to your high school chemistry class, where they taught you about the law of conservation of mass—the law states that mass cannot be created or destroyed. So, then, where does it go? According to science, it can't just disappear.

When a puddle on the street dries up, the water evaporates into particles in the air—it doesn't cease to exist. The same is true with your body fat. The decreasing number on the scale may make it seem like it's disappearing, but the fat has to go somewhere. We asked our experts to explain what happens with our bodies when we lose weight.

How Does Fat Leave the Body?

When fat metabolizes to create energy for your body to use, it produces a few waste products that expel from the body in different ways, says Fatima Cody Stanford, M.D., M.P.H., obesity medicine physician at Harvard Medical School and Men's Health advisor.

The two main bi-products are water and carbon dioxide. Water will expel itself via urination and sweat. We will breathe out the carbon dioxide, says Jeffrey Crespin, M.D., M.B.A., gastroenterologist and obesity medicine specialist.

Tips to Lose Fat:

Unfortunately, though, you can't breathe or sweat your way to fat loss. And, now that you know the mechanism for how fat exits the body, you may be thinking its time to get a jumpstart on your weight loss journey. Here are a few tips to get on track to your best self.

Eat Naturally

Natural foods are easier for our bodies to break down than processed foods. Keeping processed foods minimal will help in weight regulation.

"Evaluate your food and see if it looks like what you see in nature," Cody Stanford told Men's Health. "If it does not, it is likely processed, which can be problematic for weight regulation."

Don't Neglect Breakfast

It's scientifically proven: Those who eat a good amount of their calories towards the beginning of the day tend to do better with controlling their weight, according to a 2019 study published in Nutrients.

Plus, there's no shortage of healthy, filling breakfasts to add to your routine.

Keep Moving

Exercise in any form will help you burn extra calories. Whether it's a simple walk, an hour hitting the weights, or a long bike ride—any kind of movement is going to up your calorie burn, adding more to your calorie deficit (as long as your eating is in check, that is).

Simply adding in steps is enough to aid in weight loss, according to a study published Obesity. Find ways to walk more, like walking to the store or taking the stairs instead of the elevator when you can.

Watch Your Portion Sizes

If you're not feeling like changing what you eat, maybe changing how much you eat will be better for you. If you're looking to keep hold of your favorite, maybe not-so-healthy foods—just try to eat less of them.

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