Boost your metabolism – how it works and how you can influence it

What is metabolism?

Metabolism consists of three parts:

1. ‍Basal Metabolic Rate (BMR) – this refers to how much energy your body uses at rest to maintain vital functions.
2. ‍Thermic Effect of Food (TEF) – this is the amount of energy required to break down and process the food you eat.
3. ‍Physical activity – this includes all the energy your body uses when you move: both structured exercise and everyday movement.

Together, these components determine how much energy your body needs each day.

Basal metabolism – the body’s energy needs at rest

Basal Metabolic Rate (BMR) is the amount of energy the body needs at rest to maintain vital functions such as breathing, circulation, brain activity, cellular processes and temperature regulation. It accounts for around 60–70 per cent of all the energy you use in a day, making it the largest component of your metabolism. BMR is mainly influenced by:

• ‍Body size – larger bodies have more tissue and therefore require more energy.
• ‍Body composition – muscle mass uses more energy than fat tissue.
• ‍Individual differences – genetic factors influence how much energy we burn at rest. The difference can be as much as around 250 kcal per day between two people with the same weight and body composition.

The difference between men and women is mainly due to the fact that men generally have a larger body size and more muscle mass.

Physical activity

All movement you do throughout the day requires energy. This is usually divided into two parts:

• ‍Training-related activity – planned physical activity such as walking, strength training, running, cycling, group exercise and similar forms of training. This can account for a large share of your total energy expenditure if you train frequently.
• ‍NEAT (Non-Exercise Activity Thermogenesis) – all spontaneous movement that is not planned exercise, for example walking to the bus, standing up, taking the stairs, cleaning, tidying, playing with children or gesturing while you talk. This part can vary greatly between individuals and has a major impact on how much energy you use each day. Differences in spontaneous, often unconscious movement are an important reason why two people with the same weight and body composition can still have very different energy needs.

The thermic effect of food (TEF)

When you eat, the body must use energy to break down, absorb and convert food into energy and building blocks. This process is called the thermic effect of food (TEF) and accounts for roughly 10 per cent of your daily energy expenditure.
The amount of energy required depends on the composition of the food: protein requires the most energy to process, carbohydrates slightly less and fat the least. By eating a protein-rich and varied diet, you can influence this part to some extent while also helping to preserve muscle mass – something that benefits your metabolism over time.

Is it possible to “speed up” your metabolism?

Metabolism is influenced by several different processes in the body, and while there are no quick fixes, there are areas you can affect. Here are the most important, evidence-based factors – along with tips on how to support your metabolism.

1. Build and maintain muscle mass

Muscles are the body’s most energy-demanding tissue, both at rest and during physical activity. When you strength train and increase your muscle mass, you raise your basal metabolic rate, which contributes to a higher overall metabolism.

How to do it:

• Aim for 3 strength-training sessions per week.
• Train the major muscle groups: legs, back, chest.
• Gradually increase weights or resistance so the body continues to adapt.

2. Prioritise protein in every meal

Protein requires more energy to break down and process compared with fat and carbohydrates. This increases the thermic effect of food and helps preserve muscle mass during weight loss.

Good sources: fish, eggs, legumes, chicken, tofu, dairy products.

3. Physical activity – move more in everyday life

You do not need to train intensely to influence your energy expenditure. All movement counts, and even small increases in daily activity can make a difference over time. Less sitting and more natural movement opportunities contribute to a higher total energy expenditure.

Examples of simple ways to reduce sedentary time:

• Incorporate more occasions to walk throughout the day.
• Take the stairs when possible.
• Alternate between sitting and standing.
• Take short breaks to stretch or move around.

4. Focus on sleep and recovery

Lack of sleep affects several hormones that regulate hunger, fullness and energy balance. This can lead to overeating and also affect the body’s ability to build and maintain muscle mass – something that, over time, can influence body composition and thereby metabolism negatively.
In addition, our habits often change when we are sleep-deprived, such as moving less or choosing more energy-dense foods, which can reinforce the effect even further.

How to improve your sleep:

• Create a calming evening routine – switch off screens, drink a cup of tea, read a few pages of a book.
• Optimise your sleep environment: a cool, dark and quiet room makes a big difference.
• Get up at the same time every day, even at weekends – it strengthens your circadian rhythm.

Health risks and metabolism

Many people think of metabolism as “how quickly the body burns calories”, but metabolism is fundamentally about how the body processes the nutrients we eat and converts them into energy. When these processes do not function as they should – for example due to hormonal disturbances, insulin resistance or certain illnesses – it can affect energy levels, blood sugar regulation and, over time, increase the risk of conditions such as type 2 diabetes and cardiovascular disease.

To reduce these risks, it is important to focus on physical activity and a balanced diet. Through regular exercise you can increase your muscle mass and thereby raise your metabolic rate. A diet that contains adequate protein, fibre and healthy fats helps the body use energy efficiently.

Low metabolism

In some cases, a low metabolic rate has a medical cause. This may be due to hypothyroidism, where the thyroid gland produces too little thyroid hormone. When hormone levels drop too low, several bodily processes slow down. Symptoms may include tiredness, feeling cold, dry skin, constipation and weight gain.

If you suspect hypothyroidism, it is important to be assessed through a blood test, as the condition is treated with medication and cannot be improved through diet or exercise. With correctly adjusted treatment, hormone levels usually normalise and the body’s metabolism functions more as expected.

There are also other factors that can influence metabolism, such as hormonal changes and certain medications or illnesses. If you find it difficult to lose weight despite making changes to your diet and exercise, or if you experience other signs that your metabolism is not functioning as it should, it is important to seek medical advice.

Myths about metabolism

There are many myths and claims about metabolism that lack scientific support. Here are some of the most common ones:

Myth: Spicy food increases metabolism

It is easy to believe that spicy food “boosts metabolism” when you become warm and sweaty from eating chilli. But this effect is misleading. Capsaicin, the compound that gives chillies their heat, can temporarily raise heart rate and energy expenditure – but only marginally and for a short time. It is not enough to affect weight in the long term.
Spicy food can be part of a healthy diet if you enjoy it, but there is no reason to eat chilli for the purpose of increasing metabolism or losing weight.

Myth: Low metabolism is a common cause of weight gain

It is uncommon for weight gain to be caused by an abnormally low metabolism. Most people who feel they have a “slow metabolism” have perfectly normal metabolic rates. Truly low metabolism is usually caused by hypothyroidism, which is diagnosed with a blood test and treated medically.

Myth: Metabolism slows down purely because we age

It is true that many people lose muscle mass with age, and because muscles require more energy than fat, this can influence overall energy expenditure.
But metabolism itself changes far less than most people think. For most of adult life, energy expenditure remains stable as long as body composition stays the same.

It is only after the age of 60 that metabolic rate begins to fall – and then only gradually, by around 0.7% per year. Much of what we perceive as a “slower metabolism” earlier in life is therefore due to changes in the body, not age alone.

Myth: People with overweight or obesity often have a low metabolism

This is generally not true. Research shows that body size – and especially the amount of fat-free mass – is what influences energy expenditure the most. This means that individuals with overweight or obesity typically have higher, not lower, metabolic rates than people with lower body weight, simply because a larger body requires more energy to function.

Medical treatment for weight loss

For people living with overweight or obesity, medical treatment can sometimes support lifestyle changes. These treatments affect hunger, fullness and energy balance, but they do not replace healthy routines. At Yazen, doctors and health specialists help you understand what will work best for you.

Summary – how to increase your metabolism

• Strength train regularly to build muscle mass and increase fat oxidation.
• Eat protein with every meal to support both metabolism and fat loss.
• Increase your daily movement – more everyday activity will contribute to better results.
• Prioritise sleep and recovery, as the body handles energy better when it is well rested.
• Regular movement and consistent eating habits over time matter far more than individual tricks.