How it Works: Fat Metabolism

By Jarrod Beachum, PA-C

Last week we talked about fat and the role it plays in our body. This week I want to discuss how it is metabolized, or broken down.

Weight loss is the process by which we take those extra fat stores and break them down. Remember that excess fat is stored in the adipose cells. When we go on a calorie-restricting diet and exercise program, that means we are taking in less calories than we burn, creating a deficit which leads to weight loss. If you recall from last week, fat has 9 kcal per gram, the most of the big three macronutrients (fat, protein, carbohydrates). So, it makes sense that the body uses it as a potent energy source.

When the body notices a deficit in calories, it will go to its first temporary fuel source: glycogen, which is stored in muscles. After about 30-60 minutes of aerobic exercise is when glycogen is depleted, and the body needs the main fuel source: fat. That is why we recommend 30-60 minutes of actual dedicated cardio, three times a week. And when we say cardio, we mean the kind where when you are exercising you can’t comfortably hold a conversation. If you can talk normally, you aren’t getting a good workout.

You might be surprised to know how the body gets rid of the fat. I won’t bore you with a biochemistry lecture. It a nutshell, the “weight” from fat loss is given off as heat, water in sweat and urine, and carbon dioxide in your breath! Body systems will become adapted over time to burn fat more efficiently, meaning that the more you exercise over time, the better you will lose weight!

For those that want to focus on losing weight safely and consistently, it is generally recommend to take in about 20-35% of your daily calories from fat. So if you are doing a 1800 calorie diet, you would need 360 of those of calories to be from good fat sources, or about 40 grams. There are websites that can estimate your caloric intake for you. You can also seek out a registered dietician who discuss this in detail with you and set you up on a plan. Do not fall victim to fad diets that completely restrict one thing over another. Restrictive diets have been shown to increase rates of social isolation, body dysmorphia, and anorexia/bulimia.

If you have any questions about this article, please come see me at 45 Urgent Care. I will be happy to refer you to a dietary specialist who can also help. Also, see Advance Rehab and Medical next door for their assisted weight loss program!

-Jarrod Beachum, PA-C