Metabolism Definition: BMR, Process, and Disorders

Metabolism is the chemical reactions that take place in your body to convert nutrients into energy. It is an essential process for human life, but it is also necessary for all living things, including animals and plants.

According to the National Library of Medicine, the energy from metabolism supports physical activities. However, it’s also essential for bodily functions like breathing, blood circulation, energy storage, cell repair and replacement, and body warmth.

Here’s a closer look at how metabolism works, how it gets measured, and related disorders.

What Is Basal Metabolic Rate?

Basal metabolic rate (BMR) is the minimum amount of energy a person needs to maintain essential body functions. It doesn't consider any extra energy needs, such as standing, walking, or performing other necessary daily movements.

The easiest way to find your BMR is to use one of the two standard equations. These are the Harris-Benedict equation and the Mifflin-St Jeor equation. These equations use constants and variables for your height, age, weight, and gender.

The resting metabolic rate (RMR) is very similar to BMR. However, there are distinctions between the two. The RMR incorporates normal activities like walking and digestion. A person undergoing strict BMR calorimetry tests in a lab would have to remain almost motionless and fast for 12 hours. However, RMR tests would be much less strict, allowing the subject to observe normal meal times and expend energy on normal tasks.

Both these figures are important for measuring the appropriate daily calorie needs and planning a diet for weight loss or gain.

How Does Metabolism Work?

The basic steps of metabolism are similar for all living organisms. As we have already pointed out, metabolism supports both anabolic and catabolic functions.

The National Library of Medicine explains the process of converting food into energy for physical activity or necessary body functions. These steps include breaking foods down with enzymes, absorbing their nutrients, and transporting them to cells, where they get converted into usable energy.

Here’s a closer look at this process:

• Enzymes in the mouth and stomach begin breaking down proteins and carbs in food.
• The breakdown continues in the small intestine, which also absorbs nutrients. Carbohydrates are absorbed as glucose, proteins become amino acids, and fats turn into fatty acids.
• The nutrients then travel to cells throughout the body in the bloodstream.
• Once reaching the cell, they are converted into energy in the form of adenosine triphosphate (ATP), which are molecules that store energy.

Cells can then store or use the energy as needed.

Factors That Affect Metabolic Rate

Metabolism is a complex process. Different factors can affect the rate of nutrient breakdown, absorption, and energy production and storage.

Here are the factors that influence this process:

• Age can bring natural hormonal changes and lower muscle mass, both of which slow metabolic rates.
• Body composition also plays a role in metabolic rate. Muscle tissue burns more calories than fat tissue, leading to a faster metabolism for people with lower body fat and more muscle.
• Eating and diet are also important. This includes meal timing. Smaller portions, for instance, may give the body more time to properly absorb nutrients and filter waste.
• Nutrient-rich foods can give the body more usable fatty and amino acids and less waste to process. This can speed up metabolism.
• Proper gut health in the stomach and intestines can ensure the right balance of enzymes and beneficial microbes to efficiently break down and absorb nutrients and remove unneeded waste.

External factors, like temperature, can increase metabolic rates as the body works harder to regulate its internal temperature.

What Causes Slow Metabolism?

Some internal and external issues can slow down your metabolism and potentially lead to unhealthy weight gain and health problems.

Though slow metabolism can happen naturally as you age, when you're over 55, it’s more often the result of a sedentary lifestyle that leads to muscle loss and fat gain. Also, practices like dieting, often seen as good for metabolism, can actually slow the rate down. The body will try to conserve energy by limiting metabolic processes if it does not get enough nutrients.

If you have these problems, you can take steps to boost your metabolic rate.

How Does Metabolism Affect Weight?

Your BMR is an important baseline for any weight gain and weight loss efforts. Slow metabolism can lead to weight gain even if you have a normal diet. However, if you have a normal BMR, you should be able to better manage your weight.

For example, if someone needs 2,500 calories to provide energy for an entire day, they will lose weight if they either consume less than 2,500 calories or take steps to burn more calories through exercise. Many people may choose to do both. You might eat 2,200 calories and then exercise to burn an additional 400 calories, giving yourself a net total of 1,800.

How To Maintain a Healthy Metabolism

A healthy metabolism rate is essential for health and weight regulation. Fortunately, you can help maintain this vital body function.

Here are some simple steps to take:

• Exercise using weights or bodyweight calisthenics to build or maintain muscle, which will increase metabolism. Use cardio exercises to maintain a healthy weight and limit fat gain.
• Eat a balanced diet with protein, carbohydrates, and healthy fats. Dine during regular intervals during the day and count calories to avoid consuming more than your body needs.
• Manage stress and get enough sleep to ensure your hormonal system functions properly and doesn’t disrupt your metabolic processes.

You can also visit your physician to check thyroids, gut health, and enzyme levels to ensure your digestive and energy systems are functioning properly.

How To Gain Weight in a Healthy Manner

Many people find themselves struggling to gain weight. If you’re active, having more muscle tissue can raise your basal metabolic rate, meaning you burn more calories at baseline to begin with, and gaining weight can be difficult.

Here are some steps you can take to maintain a healthy weight:

• Change your diet to include more calories. Add more nutrient-dense foods so that your metabolic system gets enough energy.
• Time your meals so you eat more often, increasing your calorie intake without overeating at traditional meal times.
• Focus on weight training to build muscles. Muscles are denser than fat, so they weigh more in terms of volume. Combined with more protein, these exercises can lead to weight gain.

You can consult a dietician to find a specific balance of meal times, calories, and nutrients to gain weight without harming your health.

Conditions and Disorders Related to Metabolic Rate

Health conditions and hormone disorders can affect metabolism. These can lead to unexpected weight gain or weight loss and hamper your ability to stay healthy.

Here are the most common of these conditions:

• Thyroid disorders can disrupt metabolic processes. Producing too much or too little thyroid hormone could cause an overactive or underactive metabolic system.
• Diabetes involves the improper absorption of glucose. It can slow down your metabolic rate and lead to weight gain and other health problems.
• Obesity can slow down your metabolic rate as muscle gets converted to fat. Weight gain can also lead to other conditions, like diabetes, that lead to additional metabolic problems.

Consult medical professionals and find reputable health information sources to learn about metabolic rates and to find out how to maintain healthy metabolism through diet, exercise, and other practices.

Disclaimer:

The information provided on this website is for general informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional consultation, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. If you think you may have a medical emergency, call your doctor or emergency services immediately.