Metabolism- Speed up your metabolic rate

Metabolism & Metabolic Rate

The word metabolism is something that often gets used in conversation around reasons for being overweight. You most likely have heard people saying they have a really slow metabolism which is why they put on weight. On the other hand, you might know someone who seems to be able to eat anything they want and still manages to not put on a single pound. In this article, I will discuss what metabolism is, what factors affect metabolism and how you can improve your metabolic rate.

Firstly, metabolism is defined as the chemical reactions in the body's cells that keep you alive/functioning. Metabolic rate is defined as the amount of energy your body uses to maintain these processes. When macronutrients are ingested, they go through a series of processes in order to be broken down and utilised for energy. Firstly, I will briefly discuss the process of the breakdown of each macronutrient (fats, carbohydrates & protein) within the body.

Carbohydrates are broken down mechanically (through chewing) and chemically (eg. enzymes). Carbohydrates are broken down into glucose, fructose and/or galactose, which are then absorbed into the bloodstream and transported to provide energy for the body. For times where the body does not require this additional glucose, it is then stored in either the muscles or liver in the form of glycogen. Glycogen is simply the stored form of glucose. The process of glucose to glycogen is called glycogenesis. Glycogen is then utilised to provide the body with fuel when blood glucose levels are low. This process occurs by glycogen converted back into glucose which is known as glycogenolysis.

Fats are broken down into triglycerides, these triglycerides are made up of glycerol and fatty acids. The enzyme lipase and bile help to emulsify fats. Fats are then used to provide the body with energy and is the primary source of fuel for low intensity activity.

Protein is broken down into amino acids. Most of the digestion of protein occurs within the stomach where hydrochloric acid and the enzyme pepsin cause most of the chemical breakdown, whilst further mechanical breakdown continues to occur until the particles are small enough to be absorbed into the small intestine. 

The breakdown of these macronutrients requires a certain amount of energy (calories). This will be further discussed in this article.

What makes up your metabolism?

Firstly, I want all of you to understand what contributes to your total daily expenditure. This is especially important when understanding your metabolism, how to increase your metabolic rate whilst understanding energy expenditure for the purpose of a body composition goal.

Energy requirements are split into resting and non-resting energy expenditure. 

Resting energy expenditure

Basal metabolic rate (BMR) is the amount of calories your body needs per day to fuel necessary bodily functions to keep you alive. BMR calculations allow us to determine the calorie requirements necessary for sustaining an individual's vital bodily functions. Even when your body is resting, in order to perform life sustaining functions such as breathing, cell regeneration, maintaining body temperature and circulation, your body uses energy. This typically accounts for two thirds of total energy requirements.

Non resting energy expenditure

Non exercise activity thermogenesis (N.E.A.T)- neat is the energy expended through the activity you complete each day outside of your ‘exercise’ window. Examples would include walking, standing, tidying your room etc.

N.E.A.T expenditure varies depending heavily on each person's lifestyle and occupation. An individual with an office job is going to have much lower N.E.A.T expenditure in comparison to someone who works a physically demanding job.

Typically neat makes up between 15 and 20% of total daily energy expenditure. Increasing non exercise activity thermogenesis is a great way to burn more calories, increase total daily expenditure and boost your metabolic rate.

Exercise activity thermogenesis (E.A.T)- is classed as planned and structured physical activity with the objective of improving health. Participating in sports or going to the gym falls in the E.A.T category.

The Thermal effect of food (T.E.F) Each macronutrient requires a certain amount of energy (calories) in order to be broken down and absorbed by the body, in order to be used for fuel. Carbohydrates typically use 5-15%, fats 0-5% and protein 20-35%. For example, if you consumed 100g of protein, 20-35 calories would be used in order to break down and absorb this macronutrient.

Factors that affect your metabolism

Genetics-There are several factors affecting metabolism that you can’t change. For example, your sex plays a role. Males typically have a higher basal metabolic rate than females. Age is also a factor, as metabolism tends to slow with age, largely due to loss of lean muscle mass. Some people are born with metabolic disorders that affect how they metabolise certain nutrients. Genetics play a role in determining muscle size and muscle capacity, both of which exert an impact on metabolic rate.

Physical activity-The more energy you expend, the more calories your metabolism must burn to keep up. As such, a high level of physical activity may serve to increase your metabolic rate. Resistance training causes an increase in muscle mass. This increase in muscle mass increases metabolism, this is due to muscle cells requiring more energy than fat cells.

Sleep – More recently, researchers have found a potential link between sleep and healthy metabolism. Studies have shown that a lack of sleep or poor sleep quality can negatively affect the hormones responsible for regulating your metabolism. 

Stress- High stress levels can also have an impact on your metabolism, In particular cortisol. This is commonly referred to as your stress hormone and can play a significant role in your metabolic rate. This is because when cortisol is released in times your body is under stress, this sends your body into fight or flight mode, temporarily pausing regular bodily functions and therefore slowing down your metabolism.

Food plays a pivotal role in nourishing a healthy metabolism, as it supplies essential nutrients such as vitamins, minerals, amino acids, and essential fatty acids. These nutrients must be sourced from external food intake for the body to function optimally. A deficiency in any of these vital elements can have repercussions on our overall health. A combination of diverse dietary choices and regular physical activity can contribute to an individual's metabolic rate. 

Notably, the energy demands of muscle cells surpass those of fat cells, which explains why individuals with higher muscle mass typically exhibit elevated metabolic rates. As individuals age, they tend to accumulate more body fat, which is one of the contributing factors to the gradual decline in metabolism over time.

Furthermore, distinctions between men and women are evident, with men generally possessing greater muscle mass, denser bone structure, and lower body fat percentages. Consequently, men typically require a higher daily calorie intake and, consequently, exhibit higher metabolic rates.

Metabolism for overweight humans

Genes unquestionably play a pivotal role in determining muscle size and one's capacity to build muscle, both of which exert an impact on metabolic rate. It's worth noting that overweight individuals may, in fact, have a heightened metabolism due to their increased energy requirements, necessary for maintaining their larger body size.

It's important to keep in mind that crash diets can have an adverse effect on metabolism. These "quick-fix diets" may cause rapid weight loss, but they often force the body to break down muscle for energy, which, in turn, reduces muscle mass and results in a slower metabolism. Reduced muscle mass and a sluggish metabolism make it easier to regain weight once the crash diet is discontinued.

Furthermore, research has indicated that people tend to underestimate their calorie intake. When asked to recall their food consumption over the past 24 hours, many individuals typically report consuming less than they actually did. This underreporting suggests that the more prevalent reason for weight gain is the consumption of more calories than the body expends throughout the day, rather than a genetically slow metabolism.

Boosting metabolic rate

The most effective means to boost metabolic rate is through an increase in physical activity. Numerous studies have consistently demonstrated that heightened levels of physical activity correspond to reduced obesity rates. For instance, the Copenhagen City Heart Study, which encompassed over 3,653 women and 2,626 men, revealed that both genders are less prone to obesity when they engage in moderate to high levels of leisure-time physical activity (Petersen et al., 2004).

To conclude

There are many factors that affect your metabolism, some of which are controlled by genetic factors. However, we can control certain variables that allow us to speed up our metabolism.

The main ways to do so are:

Engage in more physical exercise (E.A.T & N.E.A.T)

Engage in resistance training to increase muscle mass

Consume a high protein diet

Prioritise quality sleep (7-9 hours every night

Reduce stress levels

Jacob Smith

31/01/2024