Metabolism and Metabolic Rate: What’s the Difference?

As a dietitian, I find myself and others commonly using metabolism and metabolic rate interchangeably.

But what do these terms actually mean both from a physiological sense and for your weight journey? Let’s discuss! 

Defining Metabolism and Metabolic Rate

Despite often being used interchangeably, metabolism and metabolic rate are not the same things. 

Metabolism refers to all of the chemical reactions that occur to keep your body functioning. These include breathing, digestion, delivery of nutrients to cells, utilization of energy, and elimination of waste products. 

When talking about how many calories your body burns, it’s not uncommon to use the word metabolism. However, what you’re really referring to is metabolic rate. 

Metabolic Rate

Metabolic rate refers to the rate at which your body burns calories. This number is affected by numerous factors, which we’ll discuss next. 

But before we do, there are two additional terms that you’re likely to come across when researching metabolic rate:

• Basal metabolic rate (BMR): Your BMR is the number of calories your body needs to perform its most basic, vital functions. Or in other words, it’s the amount of calories that your body needs just to exist, without taking into account any other external factors. I like to think of BMR as the hard-stop when it comes to setting calorie goals. If you’re eating below your BMR, then you aren’t providing your body with enough calories. 
• Resting metabolic rate (RMR): Also called resting energy expenditure (REE), RMR is the number of calories that your body uses at rest. Or another way to think of it, it’s the number of calories you’d need if you were just laying in bed all day doing absolutely nothing. 

RMR and BMR are often used interchangeably.

While they are different, RMR is a good estimate of BMR. In fact, unless you undergo rigid testing of your BMR and RMR, chances are most online calculators will give you the same number for each. 

So, to quickly recap, metabolism refers to all the chemical and physical processes that occur in your body.

Whereas metabolic rate is what gives you an idea of how many calories your body burns. 

Total Metabolic Rate 

Now, keep in mind that your BMR and RMR are the number of calories your body needs just to perform basic functions. 

Your total metabolic rate is a combination of: 

• BMR
• Thermic effect of food (number of calories used to eat, digest, and absorb foods and nutrients)
• Physical activity (including purposeful exercise as well as activities of daily life)

As the thermic effect of food makes up a very small percentage of your metabolic rate, most calorie estimators only use BMR and activity level to determine your daily calorie needs. 

For example, if your BMR is 1300 calories and you burn 700 calories throughout the day from exercise and just general movement, then you’d need approximately 2,000 calories to support your current weight.

Factors That Affect Your BMR

You may be wondering why some individuals have a higher metabolic rate than others.

While there are likely differences in physical activity level, chances are they also have a higher or lower BMR. 

Here are some factors that can affect your BMR: 

• Sex: in general, men have a higher BMR than women. 
• Body size: this includes height and weight. 
• Body composition: this refers to your percent body fat and muscle mass.
• Age: in general, our BMR slows down as we get older.
• Genetics: as with many things health-related, our genetics play a role in determining our BMR.
• Hormones: in particular thyroid hormones can affect your metabolic rate and are commonly tested for if you’re experiencing sudden weight gain or loss. 
• Food intake: consuming too few calories can cause your body to slow down its BMR in order to preserve energy.

Ways You Can Influence Your Metabolic Rate

Especially if you’re trying to lose or maintain your weight, you may be wondering how to boost your metabolic rate or at least keep it from slowing down. 

While some factors of metabolic rate are out of your control, like age, height, and genetics, others can be impacted by your behaviors.

Below are 5 ways that may help increase your metabolic rate. 

Note: if you’re concerned that you may have an issue with your thyroid, be sure to make an appointment with your healthcare provider to have your levels tested. 

1. Move More

This one is pretty simple, but it’s one that many of us don’t prioritize enough. Overall, finding more ways to add movement to your day will increase the number of calories that you burn. 

While this does include planned workouts like running or kickboxing, it’s specifically beneficial to reduce the amount of time you spend sitting during the day. 

Make a list of ways you can move more each day such as adding in short walks, taking stretch breaks, or standing while working.

2. Add Intensity To Your Workouts

More intensive workouts burn more calories. So how do you make a workout harder? 

Here are some ideas to try:

• Increase the intensity, such as adding in sprints.
• Add resistance by using heavier weights, running up a hill, or cranking up the resistance on the spin bike.
• Try a new type of workout, such as cardio kickboxing, zumba, or adding deadlifts and supersets to your weight lifting sessions.
• Slow down when lifting weights. Rather than doing your bicep curls quickly, slow down the pace and make sure to use a full range of motion to really work the muscle. 

3. Increase Muscle Mass

Muscle is a metabolically active tissue, which is a fancy way to say that it burns calories at rest.

Gaining muscle requires both resistance workouts and proper nutrition. Yes, protein is important for muscle, but so are carbs and adequate calories.

In fact, if you’re having trouble gaining muscle, there’s a chance that you might not be eating enough calories to support muscle growth. 

For more on gaining muscle while losing weight, be sure to read our previous article on the Protein Pacing Diet. 

4. Eat Enough Calories

As mentioned above, eating too few calories can actually cause a slow down in your metabolic rate. 

So, as tempting as it might be to just see how low you can go with calories in order to lose weight, you’ll likely end up doing more harm than good. 

While you do need a calorie deficit to lose weight, this is a good reminder that you don’t have to cut calories drastically.

Instead, make sure that you’re eating enough to cover your BMR, meet your nutritional needs, and fuel your activities during the day. 

Also, keep in mind that your calorie needs can vary day by day.

Especially if you have some days where you engage in more strenuous, long workouts like hiking, snowshoeing, or a race, you may need to up your calories a bit that day to provide your muscles with the fuel that they need. It’s best to pay attention to your hunger signals to regulate your calorie intake.

For more on how low is too low when it comes to calories, be sure to read our previous post. 

5. Lose Weight Gradually

Rapid weight loss is often due to a combination of water, muscle, and fat loss. As we mentioned earlier, maintaining muscle mass is important for boosting calorie burning.

Instead of giving into fad diets that promise quick weight loss, focus on losing weight at a slow and steady pace.

Plus, losing weight at a slower pace generally means that you’re creating lasting habits that will help keep the weight off in the long term.

The Bottom Line

The number of calories that your body burns each day is referred to as your metabolic rate.

There are several behaviors that may help boost your metabolic rate to support weight loss or prevent weight gain. 

In addition to using your Lose It! App, it’s always a good idea to meet with a registered dietitian to help determine the optimal amount of calories for your health goals and lifestyle.