If you’ve ever taken a group exercise class where each participant’s heart rate and projected calorie burn are shown on a screen, you are aware of how much these numbers fluctuate from person to person. Additionally, you may have noticed that men often burn more calories than women. But have you ever questioned why, even during the same workout, different people burn calories at such disparate rates?
The processes in your body that break down nutrients for energy, support growth, and other purposes are collectively referred to as the metabolism. However, metabolism is anything but straightforward. According to Anya Rosen, RD, a virtual functional medicine practitioner based in New York City, “there is a constant ebb and flow of reactions that build or repair our body (anabolism) and responses that break down food and energy stores for fuel (catabolism). It is a really difficult subject to research because of how intricate it is, she continues. Your current rate of calorie burning depends on several variables. Here are the top six factors, according to scientists, that affect how many calories you burn while exercising.
Body Mass
A qualified strength and conditioning specialist and performance coach, states that in general, the more weight you have, the more calories you’ll burn every session. The more weight you have, the more energy it takes to move your body because calories are merely a measure of energy. In other words, if two persons have differing weights, the heavier person will burn more calories since they expend more energy when they move.
Larger internal organs (such as the heart, liver, kidneys, and lungs) are more common in people with larger bodies, which has an impact on how many calories are used during exercise and at rest. These organs and their processes demand energy. According to one study, variations in internal organ size can account for up to 43% of the variation in total calories burned among individuals.
One of the many reasons why losing weight is difficult is that your body burns fewer calories as you lose weight, which can result in a weight loss plateau or even weight gain. However, it’s not the only explanation. According to a recent review, losing weight can also result in other physiological changes, such as the body’s propensity to burn stored fat for energy (a process known as fat oxidation), increased ghrelin levels, which increase appetite, and decreased leptin levels, which decrease satiety.
If you’re looking to lose weight and have hit a plateau, consider working with a registered dietitian who specializes in weight loss and can help you meet your goal healthily and sustainably. Find one at the Academy of Nutrition and Dietetics.
Also, keep in mind that exercise is a boon for overall health regardless of whether you lose weight. A review published in October 2021 in iScience suggests that while increased exercise doesn’t typically lead to long-term weight loss, improved cardiorespiratory fitness is associated with better health outcomes and a lower risk of premature death, regardless of weight.
Mass of Muscle
It becomes a little trickier from here on out. A person who weighs the same but has more muscle mass will burn more calories than a person who has less muscle mass. “Muscle tissue consumes more calories than fat tissue,” asserts Jenaed Brodell, RD, a sports nutritionist with a private practice in London. But estimates of the number of calories one pound of muscle will burn are sometimes grossly exaggerated. Evidence suggests that a pound of muscle burns approximately five calories per day, compared to a pound of fat, which burns just about two calories per day.
Because your body needs to produce more energy to keep up with the faster pace at which your muscles are contracting, having more muscle mass will boost your total calorie burn while exercising. In conclusion, try improving your strength-training regimen if you want to increase your calorie burn. The caveat that everyone’s objectives and capabilities are different, and ultimately it’s up to you to pick how you exercise, is added by Brodell. “Evidence shows that lifting weights burns more fat [than cardio activity] and has more promising long-term benefits,” she says.
Born Sex
Gonzalez claims that generally speaking, men burn more calories both at rest and while exercising than women. However, there is no mystical explanation for why this is the case; rather, men tend to be bigger than women and have more muscle mass than women of the same age and weight. Males typically burn 5 to 10% more calories than females while at rest, and this number typically rises with exercise, according to Gonzalez.
And while women can increase their muscular mass through strength training, they can’t generally be as slim as males due to physiological differences. To sustain hormone production and childbearing, women are genetically prone to store more fat, according to Brodell.
Body fat is also necessary for storing energy, safeguarding internal organs, and supporting vital processes including growth, immunity, hormone synthesis, reproduction, and metabolism, according to the National Institute of General Medical Sciences.
Men need between 2 and 5 percent of body fat, while women need between 10 and 13 percent, according to the American Council on Exercise (ACE). However, these bare minimums might not be adequate. A healthy range for persons under the age of 40 is 8 to 20 percent for males and 21 to 33 percent for women, according to the most often referenced study on the subject, even though there is no official recommendation for the ideal body fat percentage. Nevertheless, the connection between health and body fat is nuanced and poorly understood.
Focus on the things you can control rather than worrying about how your birth sex influences your calorie burn. The final line, according to Gonzalez, is that both men and women should concentrate on increasing their muscle mass and cardiovascular fitness through a well-balanced cardio and strength-training regimen.
Age
We often lose muscle mass as we get older, claims Brodell. You can start losing up to 3 to 5 percent of your muscle mass every decade after the age of 30. It’s unclear why this happens, but a review article from July 2017 in Ageing Research Reviews suggests that it’s probably because your body becomes less sensitive to hormones that support protein synthesis, which is essential for maintaining muscle mass. Your metabolic rate, or how quickly you burn calories both at rest and while exercising, decreases as a result of this loss of muscle mass.
According to a study on human metabolism, which was published in the August 2021 issue of Science, metabolic rate may not fall throughout adulthood instead plateauing between the ages of 20 and 60 before starting to decline. The doubly labeled water approach, the industry standard for this kind of assessment, was used by the researchers to gauge the energy usage of 6,421 men and women ranging in age from 8 days to 95 years.
However, this does not always imply that everyone’s calorie expenditure remains constant as they age. According to Rosen, who also notes that it’s impossible to precisely quantify metabolism, the study on daily energy expenditure throughout a human life is “interesting, but it is not necessarily definitive proof that our concept of metabolism is erroneous.” Additionally, not all of the numerous physiological changes brought on by aging have likely been taken into account, not even by trained eyes.
Gonzalez claims that even if you cannot stop your body from aging, consistent strength training can help you maintain or even grow your muscle mass. Strength training can help you raise your resting metabolic rate, which gradually increases the number of calories you burn while at rest.
Exercise Level
It becomes easier to perform a particular exercise the more often you do it. That’s not in your imagination, Gonzalez says; given time, your body does adjust to perform tasks more readily. This is a wonderful thing all around. It implies that with practice, you may run farther or faster and that with the right kind of exercise, your muscles would be able to lift more weight.
But it also influences how many calories you burn. Gonzalez asserts that as your body adjusts to exercise, you will burn fewer calories while still exercising. This is why a novice may burn significantly more calories than someone who has been doing the same workout for years — and it’s why switching up your workout routine can increase your fitness level and potentially enhance your calorie burn. “From your lungs to your muscles to your heart to your brain, your body becomes more efficient as you become more fit,” says Dr.
Training Hardness
Additionally, likely, two people performing the same exercise aren’t burning the same number of calories. According to Brodell, someone exercising at a high intensity—which means they are breathing heavily and are unable to carry on a conversation—can burn twice as many calories as someone exercising at low intensity in the same amount of time. Additionally, just because you are traveling the same distance or performing the same exercises as someone else does not imply that you are exerting yourself to the same degree.
According to the Department of Health and Human Services (DHHS), running and walking both lower blood pressure and lower your risk of developing chronic diseases like heart disease and type 2 diabetes. However, a previous study found that adults who walked a mile burned about 89 calories while adults who ran a mile burned about 113 calories.
The Department of Health and Human Services (DHHS) states that 150 minutes of low-intensity exercise per week is sufficient to produce several health benefits, including reduced anxiety, better sleep, lowered blood pressure, increased cardiovascular fitness, and a decreased risk of slowing the progression of several chronic illnesses. Your calorie burn will improve and these benefits will be strengthened if you schedule more vigorous activities. The ACE advises raising your speed, range of motion, or weight when performing strength-training exercises to increase the intensity of your workouts.
In the end, you should attempt to avoid worrying excessively about factors that are beyond your control. Finding forms of movement that you enjoy and feel sustainable is crucial because exercise has many advantages besides just helping you lose weight. According to Brodell, “the best kind of exercise for a person ultimately relies on that person’s goals, physical condition, and ability.”