Metabolism is a term that refers to all the chemical reactions in your body that keep your body alive and functioning. However, when most people talk about “metabolism,” they’re referring to the rate at which the body burns calories. This is also known as the metabolic rate.

The rate of metabolism varies from person-to-person. Some people have a fast metabolism, meaning they burn calories more quickly than others. There are several factors that contribute to a person’s metabolic rate, including:

Muscle Mass: People with more muscle mass have a faster metabolism. This is because muscle tissue burns more calories than fat tissue does, even at rest.
Exercise: Regular exercise, especially strength training, can increase muscle mass and, consequently, speed up your metabolism. Exercising of course burns calories as well.
Movement and Daily Activities: Even when you’re not exercising, all movement contributes to your daily calorie burn, which is a part of your metabolism. This includes everyday activities like walking, cleaning, and even fidgeting. This is known as Non-Exercise Activity Thermogenesis (NEAT). NEAT can vary significantly between people depending on their daily activity levels. Someone with a physically demanding job, for instance, will have a higher NEAT compared to someone with a sedentary office job. Increasing your daily movement can therefore be an effective way to boost your metabolism and increase your energy expenditure. Metabolism is not just about the food we eat or the exercise we do, but also about our overall level of physical activity throughout the day. Every bit of movement counts and contributes to our metabolic rate, highlighting the importance of an active lifestyle for maintaining a healthy metabolism.
Hormonal Factors: Hormonal imbalances can slow down metabolic rate. For instance, conditions such as hypothyroidism can lower metabolism by decreasing the production of hormones by the thyroid gland. This reduction in hormone levels slows down bodily functions, including the conversion of food into energy, leading to a decrease in the number of calories burned by the body.
Gender: Generally, men tend to have a faster metabolism than women. This difference is largely due to body composition; men typically have more muscle mass and less body fat than women. Since muscle tissue burns more calories than fat tissue, this contributes to a higher basal metabolic rate (BMR – the amount of energy your body needs to function while at rest) in men. Continuing on from the point above, hormonal differences also play a role here. For example, the hormone testosterone, which is more prevalent in men, promotes muscle growth and fat loss. It’s important to note, however, that these are general trends and individual metabolic rates can vary widely regardless of gender.
Food Intake: The types of food you eat can also affect your metabolism. For instance, protein-rich foods require and burn more energy for digestion, absorption, and utilisation than fats or carbohydrates. This is known as the thermic effect of food (TEF). TEF is the energy your body uses to digest, absorb, and process the food you eat.
Genetics: Metabolism is partly genetic. Some people naturally have a faster metabolism.
Age: As you age, your metabolism tends to slow down. This is partly because you lose muscle mass as you get older, and (again) muscle burns more calories than fat. It can also come down to moving less as you age.
Sleep: Lack of sleep can negatively affect your metabolism and is linked to weight gain, usually as being tired makes you feel hungrier which leads you to eating more.

Understanding your metabolism better can help with weight loss or maintaining your weight. It’s important to remember that having a slower metabolism isn’t necessarily a bad thing, and it doesn’t mean you’re unhealthy. It simply means your body uses energy differently. To support a healthy metabolism, it’s crucial to maintain a balanced diet, stay active, get enough sleep, weight train if you can, and manage stress. Remember, the key to any healthy lifestyle is balance and consistency.