Some factors that promote weight loss are within your control, but most are not. Here’s what you can do to support your metabolism.
If you’ve ever attended a group fitness class where everyone’s heart rate and estimated calories burned are displayed on one screen, you know that those stats vary wildly from person to person. You’ve probably also noticed that men, in general, tend to burn more calories than women. But have you ever wondered why different people burn calories at such different rates, even during the same workout?
The truth is that metabolism, an umbrella term for all of the processes in your body that break down nutrients to create energy, fuel growth and more, is anything but simple. There is a constant ebb and flow of reactions that build or repair our bodies (anabolism) and reactions that break down stores of food and energy into fuel (catabolism). It is an extremely complex and very difficult subject to study. Various factors affect how fast or slow you are burning calories at any given time.
Here are the six factors that have the biggest impact on the number of calories you burn while exercising.
1. Body weight
In general, the more you weigh, the more calories you burn per session. Calories are just a measure of energy. So the more you weigh, the more energy it takes to move your body. In other words, out of two people of different weights, the one who weighs more burns more calories because they spend more energy moving.
Tall people also tend to have larger internal organs (like the heart, liver, kidneys, and lungs), which is a major factor in the amount of calories burned during exercise and at rest. Because these organs and their processes require energy. One study found that up to 43% of the differences in total calorie expenditure between people can be explained by differences in the size of their internal organs.
This is one of the many reasons why weight loss is so complicated. Your body burns fewer calories when you lose weight, which can lead to a weight loss plateau or even weight gain. But that’s not the only reason. A previous study explains that weight loss can also trigger other physiological adaptations, including the body’s tendency to burn stored fat for energy, a process called fat oxidation; an increase in hunger due to higher levels of the hormone ghrelin and a decrease in satiety due to lower levels of the hormone leptin.
If you’re trying to lose weight and have plateaued, consider working with a nutritionist who specializes in weight loss and can help you achieve your goal in a healthy and sustainable way. Also, remember that exercise is good for overall health, whether you’re losing weight or not. A study published in iScience in October 2021 suggests that while increased physical activity does not generally lead to long-term weight loss, improved cardiorespiratory fitness is associated with better health outcomes and a reduced risk of premature death, regardless of weight.
2. Muscle mass
This is where it gets a little complicated. A person with more muscle mass burns more calories than someone with the same weight but less muscle. Muscle tissue burns more calories than fat tissue. But claims of how many calories a pound of muscle burns are often grossly exaggerated. In fact, a pound of muscle has been shown to burn about five calories a day, while a pound of fat burns about two.
During exercise, more muscle mass increases your overall calorie expenditure because your body has to produce more energy to support the increased rate at which your muscles contract. In summary, if you want to increase your calorie consumption, you should increase your strength training. Weightlifting has been shown to burn more fat [que l’exercice cardio] and that the long-term results are more promising.
3. Gender at birth: male/female difference
In general, men burn more calories than women at rest and during exercise. But the reason isn’t magic, it’s because men tend to be taller than women and have more muscle mass than women of the same age and weight. Men typically burn 5-10% more calories at rest than women, and this percentage typically increases with exercise.
And while women can certainly build muscle mass through strength training, physiological differences mean women generally can’t be as lean as men. Women are genetically predisposed to accumulate more fat to support hormone production and childbirth. This is because body fat is also essential for functions such as storing energy, protecting internal organs and supporting key functions such as growth, immunity, hormone production, reproduction and health metabolism.
Men need at least 2-5% body fat to be healthy, while women need at least 10-13%. But these minimum numbers may not be sufficient. While there is no official recommendation for optimal body fat percentage, the most widely cited study on the subject indicates that the healthy range for adults under 40 is 8-20% for men and 21-33% for women. However, the relationship between health and body fat is complex and not fully understood.
Instead of worrying about how your birth sex affects your calorie burn, focus on the things you can control. The key is that both men and women focus on building muscle and improving cardiovascular health through a balanced program of cardiovascular and strength training.
As we age, we tend to lose muscle mass. After the age of 30, you begin to lose up to 3-5% of your muscle mass per decade. The reasons for this aren’t fully understood, but a July 2017 report in Aging Research Reviews says it’s probably because your body is becoming more resistant to hormones that promote protein synthesis, which is essential to maintaining muscle. This loss of muscle mass lowers your metabolic rate, the rate at which you burn calories, both at rest and during exercise.
A study on human metabolism, published in the August 2021 issue of Science, made headlines for finding that metabolic rate does not decrease in adulthood, but instead plateaus between the 20s and 60s and then begins to decline. In this study, the authors measured the energy expenditure of 6,421 men and women aged 8 days to 95 years using the double-labeled water method, the gold standard for this type of measurement.
You can’t prevent your body from aging, but you can maintain and even increase your muscle mass with regular strength training. Strength training can help increase your resting metabolism, which allows you to burn more calories at rest over time.
5. Fitness level
The more often you do a certain type of workout, the easier it seems. It’s not in your head, your body actually adapts to make things easier over time. Overall, that’s a good thing. This means that with training you can run faster or longer, and with the right training your muscles are capable of lifting heavier weights.
But it also affects your calorie consumption. As your body adapts to exercise, you’ll burn fewer calories for the same workouts. From your lungs to your muscles to your heart and brain, your body becomes more efficient as you get fitter. Because of this, a beginner can burn a lot more calories than someone who has been doing the same workout for years. Because of this, changing your exercise routine can increase your fitness level and potentially improve your calorie burn.
6. Training Intensity
It’s also possible for two people doing the same workout to burn different numbers of calories because they’re not doing the same workout. A person exercising at high intensity, which means you’re breathing heavily and can’t hold a conversation, can burn twice as many calories in the same amount of time as a person exercising at low intensity. And just because you’re running the same distance or performing the same movements as someone else doesn’t mean you’re both training at the same intensity.
For example, walking and running have the same benefits in terms of lowering blood pressure and the risk of chronic diseases like heart disease and type 2 diabetes. A previous study showed that adults who walked a mile burned about 89 calories while adults did running the same kilometer will burn about 113 calories.
A goal of 150 minutes of low-intensity walking per week is enough to achieve many health benefits, including reduced anxiety, better sleep, lower blood pressure, better cardiovascular fitness, and reduced heart rate or slowing the progression of certain chronic diseases.
Incorporating higher intensity exercise into your routine will increase your calorie burn and amplify these benefits even more. To increase the intensity of your workout, try increasing your speed, range of motion, or the amount of weight you use for resistance exercises.
Finally, you should try not to worry too much about things that are out of your control. Exercise has myriad benefits beyond just burning calories, and the most important thing is finding types of exercise that are fun and long-lasting. The type of exercise that works best for a person ultimately depends on their goals, physical fitness, and ability.
* Presse Santé strives to convey health knowledge in a language accessible to all. In NO CASE can the information given replace the advice of a doctor.
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