What is a Fast Metabolism?

Your metabolism is responsible for converting food into energy. The speed at which this process takes place varies between individuals. Those with a faster metabolism burn through calories at a faster rate and are less likely to put on weight.

Many of us know someone who eats vast amounts, yet retains their slim figure. These people are often subject to the envy of those with slower metabolisms. After all, we’d all love to be able to eat as much as we like without putting on weight!

In this article, we explain how your metabolism works and what it means to have a fast metabolism.

What is Metabolism?

Metabolism is a term used to describe the biochemical process of converting the food you eat into energy, which is measured in calories.

This conversion process provides the energy to power all our essential bodily functions, including breathing, movement, growth, and heart rate. Essentially, your metabolism is what keeps you alive.

The food that you eat provides the nutrients for your metabolism to break down molecules in order to release energy, known as catabolism. This in turn provides the energy needed for the body to synthesize large and more complex molecules using smaller molecules, known as anabolism.

The speed at which this energy conversion process takes place is known as your metabolic rate. This can be divided into several categories.

• Basal metabolic rate (BMR): describes the rate at which calories are burnt during sleep or rest. Your BMR provides the energy to keep your body functioning as it should and powers all essential processes such as breathing, heart rate, and body temperature.
• Resting metabolic rate (RMR): is also used to describe the minimum rate of energy expended in order to keep you alive during rest. This accounts for roughly 50-70% of your energy expenditure - so a fairly large chunk!¹
• Thermic effect of food (TEF): describes the rate at which calories are burned during digestion and accounts for around 10% of your energy expenditure.²
• Thermic effect of exercise (TEE): describes the rate at which calories are burned during exercise.
• Non-exercise activity thermogenesis (NEAT): describes the number of calories required for everyday activities, such as standing, walking around, fidgeting, and changing posture. A surprising amount of energy can be expended this way!³

What Causes a Fast Metabolism?

Metabolism speed varies between individuals. People with a fast metabolism burn through calories quickly so can consume more food without putting on weight. And vice versa.

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Genetics plays a big role in determining your metabolic rate - some people are lucky and are born with a fast metabolism. But other environmental factors also play a role. These include:

• Age: as you get older, your metabolic rate slows down and you are more likely to gain weight.⁴
• Muscle mass: muscle cells are more metabolically active than fat and require more energy during rest. If your body composition is high in muscle, your BMR will be higher and you will burn calories faster.⁵
• Body size: the bigger you are, the more energy you need to fuel your body. For example, a child will need to consume much fewer calories than a grown adult.
• Activity levels: all physical activity requires energy to power your muscles. The duration and intensity of the exercise you perform will affect how many calories you burn.
• Hormone disorders: as hormones play a role in regulating metabolism, hormone-related disorders, such as Cushing’s syndrome and hypothyroidism, can slow your metabolism.
• Temperature: the body burns calories to keep us warm. If you live in a cold climate, more calories will be required to maintain your temperature.⁶ Which explains why we crave stodgy, comforting food in the winter and lighter meals in the summer.

A common misconception is that a fast metabolism equals skinny, but this is actually not always the case. Research suggests that people with obesity often have faster metabolisms and expend more energy because it takes more effort to move around.⁷

While metabolic rate does influence your weight, if you have a fast metabolism but live a sedentary lifestyle and eat poorly, you can still become overweight. Lean people are generally more active so burn more calories throughout the day. They don’t necessarily have a fast metabolism.

Can You Speed Up Your Metabolism?

Many people believe if you are born with a slow metabolism it can’t be changed. This isn’t entirely true. While your metabolism is largely influenced by genetics, there are a number of things you can do to speed up your metabolic rate to burn more fat.

Altering your body composition and converting fat to lean muscle mass is an effective way to boost your metabolism. As mentioned earlier, this is because the body uses more energy to maintain muscle than it does fat, which raises your BMR⁸. A combination of aerobic exercise, high-intensity workouts, and strength training, is the best way to build muscle mass quickly.

However, it is commonly believed that exercise boosts your metabolism permanently. Unfortunately, this is not the case. During exercise, your metabolic rate increases as you require more energy to power your muscles. This may continue for an hour or two after you stop, but after that, your metabolism will go back to its resting rate.

Eating a diet high in protein helps support new muscle growth and maintains muscle mass. All foods temporarily raise your TEF rate, as energy is required to power digestion. But protein raises your rate significantly more than other types of food, such as carbs or fat.⁹

Staying active and generally moving around more can boost your NEAT and help expend more calories. This could be things like choosing to take the stairs instead of the lift, walking around more, using a standing desk, or doing household chores - a good motivator to keep your house clean!

Summary

Metabolism is the process of converting nutrients in food into energy to power all bodily functions. The speed at which this process takes place varies between individuals.

People with a fast metabolism burn more calories in a given amount of time and are less likely to put on weight. Your metabolic rate is determined largely by genetics, but can also be influenced by a number of environmental factors.

By remaining active, exercising, and eating plenty of protein, you can speed up your metabolism to help prevent weight gain!