Feeling the burn: the relationship between metabolism, digestion, and weight loss

Do you have a fast metabolism? A sluggish metabolism? Do you even know what that means? 


If you don’t know, you’re not alone. Even though we all talk about our metabolism — something we can either have total control over with some funny-smelling tea or is completely out of our control — most of us have no idea what it means and its impact on our digestion and weight loss goals.


Here are four things you need to understand about metabolism and its impact on your health.

1. Metabolism is an essential body process

We usually talk about metabolism as something exclusively related to our weight. But that’s a bit reductive. Metabolism is a term used to describe all chemical reactions necessary for sustaining life. It’s broken down into two categories:

  • Anabolism ‒ the buildup of substances. Anabolism consumes energy. 
  • Catabolism ‒ the breakdown of substances into a simpler form that can be used to provide energy and the basic building blocks of growth and repair. Catabolism releases energy.

We tend to think about metabolism in relation to weight because, through the process of metabolism, our bodies turn the food we eat into the energy we need. Calories are units of energy. 

2. You burn most of your energy doing basic functions

Your body needs energy to do everything, even those things we unconsciously do like breathing, circulating blood, and repairing cells. Most of the calories/energy you burn (50-80%) is spent doing those basic functions.


The number of calories your body uses to breathe and move blood throughout the body is called your basal metabolic rate (BMR), which is what we tend to think about when we think about metabolism. There are a bunch of factors that help to determine your BMR, including your age, body composition and size, and gender. 

3. BMR is just one part of metabolism

In addition to BMR, there are two other factors that determine how many calories your body burns in a day — thermogenesis and physical activity.

Your body uses energy to digest the food and beverages you consume and absorbs, transports, and stores their nutrients, a process known as thermogenesis. About 10% of the calories consumed from carbs and protein go to the digestion and absorption process.


The remainder of the energy you expend is from physical activity and exercise. Whether you’re beatboxing with Rubie or going to the bodega, you’re expending energy. Unlike BMR, which is fairly consistent, calories burned from physical activity varies significantly. Activities you do that aren’t deliberate exercises like walking to your fridge or folding clothes are known as non-exercise activity thermogenesis (NEAT) and account for 100 to 800 calories used every day.

4. Digestion plays a major role in metabolism

Even though digestion only accounts for 10% of the calories you burn, it can impact the speed of your metabolism. The energy created through metabolism fuels the cells in your body. Like your car, if you put crap fuel in it, don’t be surprised if it breaks down. Foods with processed sugar and refined carbohydrates can inflame cells causing them to release chemicals that increase weight.


A bad diet also increases the amount of yeast and bacteria in the gut, which produces toxins that can negatively affect metabolism. People who have poor gut health often experience gas, bloating, abdominal pain, weight gain, and low energy, which is attributable to low cellular energy production and low metabolism.


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