Metabolism is the combination of internal chemical processes continuously happening inside your body that keep you alive and functioning normally. Metabolism is most simply known as the process by which your body breaks down food and drink, turns it into energy, and burns calories as the energy is used. This conversion of food to energy is necessary for life-sustaining tasks such as breathing, circulating blood, digesting food, regulating body temperature, growing and repairing cells, and eliminating waste.
Even when your body is at rest, such as when you are sleeping, you are still using energy for these basic functions. In fact, the average person burns about 1,800 calories a day doing absolutely nothing. However, this number varies from person to person as the amount of energy your body burns at any given time is directly affected by the rate of your metabolism, which can be faster or slower in some people.
What Is Metabolism?
Your metabolic rate refers to how quickly your body converts and uses energy in order to function. There are two closely linked measures of your metabolic rate. These are often used interchangeably but differ slightly.
Basal metabolic rate (BMR) estimates the minimum amount of energy (measured in kilojoules) that your body needs to perform its most basic functions (breathing, digestion, etc.).
Resting metabolic rate (RMR) measures the number of calories your body burns while at rest as opposed to being engaged in any mid- to high-intensity physical activity. This measure accounts for the sorts of movements you would do while spending a day at home doing nothing (e.g., eating, going to the bathroom, walking from room to room) on top of your basic functions measured by BMR.
Your metabolic rate is influenced by a number of different factors, including:
Genes and body type – Your genetic makeup will influence your body type, size, and level of muscle growth as you develop, all of which have an effect on your metabolism. People with larger body size and greater muscle-to-fat ratio are likely to burn more kilojoules throughout the day.
Gender – In general, men tend to have more muscle than women and burn kilojoules at a faster rate.
Age – As you age, you begin to lose muscle mass and usually become less active, both of which can slow your metabolism.
Physical activity levels – People who are more physically active on a regular basis will generally burn calories at a faster rate. This is one of the few factors you actually have some control over.
Does Metabolism Slow With Age?
While it is true that metabolism slows with age, a recent, large-scale study has revealed that this actually only occurs much later in life than originally thought. The study found that from around the age of 60 years, your metabolism begins to slow down gradually each year at a rate of around 0.7%. However, for a large portion of your life from age 20 to 60 years, your metabolism actually remains fairly stable.
There are of course other factors that are linked with age that can also influence changes in the amount of energy you burn each day and affect your weight maintenance as you get older. These are mainly the amount of muscle you have and your physical activity levels. Muscle tissue uses more energy and thus burns more calories than fat, so the more muscle you have, the more calories you can burn when you use them. People tend to lose muscle mass as they get older, either as a natural part of the aging process or because they become less physically active, and their metabolism begins to slow.
Can You Boost Your Metabolism?
You have probably known people who seem to be able to lose weight quickly or more easily than others and put this down to a fast metabolism. If you have struggled with maintaining your weight, you may be looking for ways to boost your metabolism.
However, changing your metabolism is difficult. There is limited scientific evidence to support that any foods, drinks, or supplements can actually increase your metabolism beyond a temporary boost. But having a slow metabolism doesn’t mean you won’t be able to lose weight. The fact is that everyone will lose weight if they burn more calories than they consume, so the focus should be on reducing the number of calories you eat and increasing the number of calories you burn each day to create a gap (or energy deficit). Modulating your metabolism in order to maintain or lose weight is all about achieving balance.
You can influence how much energy your body needs, gets, and uses by making some key changes to your lifestyle:
- Eating a healthy, balanced diet consisting of whole foods, fiber, and protein
- Staying physically active (2.5 hours a week of aerobic and strength training activities)
- Getting plenty of sleep (ideally 7-9 hours a night)
- Taking care of your well-being to keep stress levels low
How Does Physical Activity Influence Metabolism?
Increasing your physical activity levels can help to boost your metabolism for a short period of time, but building regular exercise into your lifestyle is the best way to get long-lasting benefits for weight management. Let’s break it down to see how physical exercise affects metabolism and can help you to achieve your health goals.
When you exercise, you burn additional calories beyond what your body would normally burn in a day for its internal functioning and low-level activities. Any additional exercise you do helps to increase the gap between the number of calories going in and out of your body each day. Your body burns these additional calories while you are engaged in physical activity. Depending on the intensity of your workout, it may continue to burn calories at a higher rate for some time afterwards (sometimes referred to as afterburn). However, this short-term increase in metabolic rate will not have a long-lasting effect on your metabolism in the following days. Once you stop moving, your body generally reverts to its resting metabolic rate.
This should not discourage you from exercising, though. On the contrary, the more physical activity you do, the more energy you burn. It is currently recommended that older adults should do at least 2.5 hours of physical exercise per week that includes some aerobic-type activities and some muscle-strengthening activities.
Exercises aimed at building muscle strength and mass can also affect your metabolism, although not as drastically as you might think. This is because it takes time to build muscle, and even people who exercise regularly will only gain a pound or two in muscle each month. While muscle burns more calories than fat, the metabolic activity of your internal organs still accounts for most (up to 80%) of the energy you expend each day. So, it is best to incorporate muscle-strengthening activities into a well-rounded physical activity routine that also includes exercises to get the heart pumping.
Then, we just need to make sure that we refuel our bodies with the right kind and amount of food and drink for our energy needs. Any excess energy gets stored as fat, so be careful not to load up on calories after a workout or overindulge in high-calorie foods thinking that your body is operating with an increased metabolism.
Can Any Foods Boost Metabolism?
Not really. There is no specific food that will help you make long-lasting changes to your metabolism, but switching to an overall healthier diet that contains fewer calories is one of the best ways to get on top of your weight.
Food and drink play an important role in the metabolism and weight loss equation; at the end of the day, you need to consume fewer calories than you burn in order to lose weight. While there is some evidence to support that certain foods and beverages, like green tea, caffeine, and spicy foods, may give your metabolism a temporary boost, these alone will not make a difference in your body’s energy requirements and expenditure in the long run. Similarly, there are some misconceptions that changing when you eat meals throughout the day can impact your metabolism. For example, while eating breakfast may speed up your metabolism, this is only temporary.
Making a few changes to your overall diet, including ensuring that you eat enough fiber and protein, may help to increase your metabolism. Your metabolism increases whenever you eat, digest, and store food, a process called the thermic effect of food. Protein and fiber have a higher thermic effect compared with fats and carbohydrates because it takes longer for your body to digest and absorb them, so you burn more energy.
Can Supplements Boost Metabolism?
Unfortunately, there is no quick fix solution to altering your metabolism or losing weight quickly. Anything that claims to do this should be viewed with caution. Dietary supplements promoted for weight loss often contain a mix of ingredients like herbs and plant extracts, minerals, dietary fiber, and caffeine that are claimed to do things like reduce appetite and body fat, and increase metabolism. However, there is little evidence of their effectiveness. The most that has been established by the National Institutes of Health is that some ingredients (such as bitter orange, green coffee extract, and raspberry ketone) may have temporary and minor effects on metabolism and weight loss in some people.
It is important to note that dietary supplements are not held to the same regulatory standards as drugs and medications. They are not reviewed and approved by the FDA for safety and effectiveness in order for them to be on the market. In addition, dietary supplements may contain substances that have serious side effects for you or a higher dosage of ingredients that may put your body out of balance in other ways. Always speak to your doctor before taking any new supplements as they will be able to advise whether this is the right choice for you.