In our increasingly diet-centric culture, there's a lot of talk about metabolic rate. However, much of this conversation fails to provide information about how metabolic rate relates to bodily function and instead focuses on how it affects the pace of weight loss.
But just like about every other body function, it's never as simple as black and white.
Metabolism and your body
According to the Cleveland Clinic, metabolism refers to the chemical (metabolic) processes that take place when your body converts foods and drinks into energy. It's a complex process that combines calories and oxygen to create and release energy.
"The metabolic rate describes the quantity of energy that the body is able to utilize in a certain period of time," explained Deena Adimoolam, M.D., a specialist in endocrinology, diabetes and metabolism at Mount Sinai Hospital in New York City.
She said metabolism provides us with energy that allows us to live. While people often think of metabolism only in relation to weight gain or loss, she said it has a much more important function. Metabolism refers to the use and storage of all forms of energy, including the glucose, proteins and fats the body needs to function.
Understanding that metabolic rate is a regular bodily function and not just a factor determining weight loss can help people have a more positive and balanced perspective of their health. Your metabolism is always at work: It doesn't rest when you do and it constantly provides energy for all bodily functions, such as breathing, circulating blood, digesting food, growing and repairing cells, managing hormone levels and regulating body temperature.
"Metabolism is like the engine of the body and can run faster or slower in different individuals," said Angela Marshall, a board-certified internist and metabolism specialist, and president and CEO of Comprehensive Women's Health in Silver Spring, Maryland. "Slow metabolism refers to a slower rate of chemical processing due to various factors."
Metabolic rate is a regular bodily function and not just a factor determining weight loss—your metabolism is always at work.
However, Adimoolam explained that everyone's metabolic rate is different.
"A slow metabolism suggests that the body takes longer to utilize energy," she said. "A fast metabolism suggests that the body takes a shorter time to utilize energy."
Metabolism is affected by many factors, such as glucose production and expenditure, fat production and expenditure, energy expenditure, body weight, insulin, growth and overall health. Other factors include age, gender, muscle versus fat composition, hormones—including thyroid, leptin and others—physical activity and many others.
Promoting a healthy metabolism is important to help maintain general health and well-being. While there are some forms of fasting that are popular and seem to help some people with portion control and diet, your body may eventually adjust to skipping meals, which can cause you to potentially lose out on important nutrients, depending on activity levels and other health issues. Your primary care provider may give you a referral to a nutritionist to determine if fasting is appropriate for you.
The better approach is to fuel your metabolism with fresh fruits and vegetables, lean proteins, healthy carbohydrates and fats. It is also important to quit smoking because that can slow your metabolism and contribute to many other chronic conditions.
What it means to have a metabolic disorder
"There are many rare disorders of metabolism due to genetic mutations which impact the metabolism of certain types of proteins [amino acids], fats, etcetera," Adimoolam said. "The most common disorder of metabolism, though, is type 2 diabetes, which impacts the metabolism of glucose, a major source of energy."
Marshall added that in general, metabolic disorders usually arise from defects or an absence in production of the enzymes, that is, basic chemicals necessary to process most of the chemical reactions in the body.
"There are over a thousand different enzymes in the body, so there are many things that can be wrong," Marshall said. "Some examples include lysosomal storage disorders like Tay-Sachs, Fabry disease, Hurler syndrome, Niemann-Pick and more."
Metabolism is regulated by the endocrine system, so any endocrine disorder affects metabolism. Examples include Cushing syndrome, which occurs when the body has too much of the hormone cortisol over time, and hyperthyroidism, which occurs when the thyroid gland makes more thyroid hormones than the body needs.
How metabolic rate affects your sex life
Metabolism affects every single function of your body, and that includes the energy you need for sex.
"Metabolism can cause disruption in your sex life," Marshall said. "One example of this is hemochromatosis, which causes an abnormal buildup of iron deposits in the testicles, leading to sexual dysfunction and erectile dysfunction."
However, it's important to note that barring a metabolic disorder, it is unlikely that your metabolic rate will negatively affect your sex life.
Despite everything you may have heard about metabolic rate, the best action you can take is to focus on a healthy diet and exercise to maintain your body's normal metabolism. If you have an underlying genetic condition, you may want to talk to your doctor about questions related to treatments and their impact on health, diet and well-being.
As always, if you have any concerns regarding your metabolism or general health—such as extreme fatigue and unexpected weight loss or gain—speak with your primary healthcare provider.