How Does Your Metabolism Change As You Age?

The metabolism is a system of chemical reactions within the body that processes food into nutrients and energy. The energy conversion that takes place is used by the most basic functions of the body, such as breathing, circulation, and digestion. The energy that is left over from the food you eat is then utilized to help you get through the day, exercise, and live your life. But as you age, the speed of your metabolism begins to slow down. There are a few reasons behind those changes, so today let’s answer the question: how does your metabolism change as you age?

Metabolism and aging

As you get older, the metabolism doesn’t always work in the same way it did when you were a child or young adult. If you’ve ever reflected that you “can’t eat the same way you did when you were younger”, you’re aware of these changes!

The slowing of the metabolism comes down to a few different factors. They include:

  • The resting metabolic rate (RMR). Your RMR is the number of calories that your body needs to keep you alive. It is the energy needed to perform the most basic bodily functions.
  • Thermic effect of food (TEF). This is how much energy or calories are burned away through digestion or absorption of the food you eat. Even the process of fueling your body requires energy to put the food to good use.
  • Exercise. Exercise is one activity that everybody uses to burn calories, but the amount a person gets also effects their metabolism.
  • Non-exercise activity thermogenesis (NEAT). This is how many calories it takes to perform basic tasks such as standing, washing dishes, or other chores.

Of course, there are other factors that affect how a person’s metabolism functions, including height, hormones, age, and the amount of muscle a person has on their body.

older man and woman in flower field
Image by Jaddy Liu on Unsplash: Older adults tend to exercise less, and that plays a role in a slowing metabolism.

Why does your metabolism slow down as you age?

There are a few reasons why the metabolism will slow down with age. Some of those factors are lifestyle-related, whereas others are biologically driven. Although lifestyle factors can be changed, biological aging cannot be stopped.

Exercise and diet

One specific driver related to metabolism slowing with age is exercise. As people get older, their ability or drive to exercise becomes lower. Activity levels have such a big impact on metabolism that research has shown that exercise and non-exercise activity or movement can account for up to 30% of your daily calorie expenditure.

Although the connection between less activity and aging isn’t entirely clear, research has also found that people aged 50 and older don’t typically exercise outside of work at all. Older people also tend to eat less, which can affect the metabolism’s speed as well.

Muscle mass

A key lifestyle and biological factor that comes into play with a slowed metabolism is muscle mass. Since people are not exercising as much as they used to past a certain age, they are bound to lose some muscle. Combine that with the natural aging process and the average muscle loss that simply occurs as a result (also known as sarcopenia), and it shows exactly why the metabolism slows as a person gets older.

After a person turns 30, the average decline in muscle is anywhere from 3–8%. The reason this affects your metabolism is because muscle plays a large role in how many calories the body burns at rest (RMR). 


Hormones have also been shown to play a role in metabolism. As the body ages, the production of certain hormones such as estrogen, testosterone, and growth hormone begins to decrease. This deduction in hormone levels also slows the metabolism.

Cellular changes

As the body ages, cellular components and chemical reactions within it begin to change. Two specific cellular components that play a role in chemical reactions that affect the metabolism are sodium-potassium pumps and mitochondria. While mitochondria is tasked with creating energy for cells, sodium-potassium pumps help with the contractions of muscle and the heart as well nerve impulses. These two components begin to lose their ability to effectively perform as the body gets older.

Although these two things contribute to the slowing of the metabolism, they account for a small part of the slowing process when compared to activity levels and the amount of muscle a person has on their body.

older woman
Image by Anthony Metcalfe on Unsplash: How much does metabolism change with age?

At what age does metabolism peak?

Although the exact age of peak metabolic function varies from person to person, research has shown that the early 20s are the age that shows the most efficient metabolism. At this age, the number of calories burned by the body while at rest are the highest. This could be due to a lot of reasons, but like all ages and metabolism, it can most likely be attributed to exercise levels and muscle mass.

Is there anything you can do to stop metabolism changing?

Although there is nothing you can do to stop the cellular process of aging, there are ways around a slowing metabolism. Keeping up with regular exercise can be a great metabolism boost. Strength training, for example, is a great way to help build and maintain muscle mass and provides the overall benefits of exercise. Studies have shown that when older people do strength training, they can increase their RMR by close to 8%.

High-intensity interval training is also a great way to help the body burn calories. This is because it has been shown to cause the body to continue burning calories for as long as 14 hours following the end of the exercise session. 

Diet can also play a role in speeding up the metabolism. By eating a diet that has a lot of protein, you can increase metabolism. This is because protein-rich foods need more energy to be digested. And it’s not always what you eat that helps metabolism, but also how much you eat. Eating too little can cause the metabolism to slow down, because by eating too little calories, the body begins to reserve energy, leading to a decreased metabolic rate.

Fighting the passage of time is always going to be a losing battle, and aging is just a natural part of life. That doesn’t mean you have to give up on a healthy and speedy metabolism. By keeping up with exercise and muscle mass, you can help to combat the natural process of metabolic slowdown.

Featured image by Abigail Keenan on Unsplash

What Is The Longevity Gene And Can We Hack It?

As soon as life begins, the body begins the aging process. It’s a natural human process that everyone experiences. As people age, biological, psychological, and physiological changes occur. Some of these changes aren’t health risks, but others contribute to age-related health disorders.

It isn’t until adulthood that the aging process begins to lead to the deterioration of many organs, such as the brain. Research on exactly when the decline of cognitive function begins as in relation to aging is mixed, with some studies suggesting it begins as early as 27 while others say somewhere around 45 is more accurate. This is just one measurement of aging, as the process occurs within all cells, organs, and bodily systems.

Longevity isn’t part of the aging process, but rather the result of how quickly it occurs on a person-by-person basis. Some people age more slowly than others in many regards, while others aren’t as lucky. Longevity isn’t only dependent on the natural aging process, but also on other factors including genetics, environment, and lifestyle.

Longevity genes and aging

Researchers across the globe have been working tirelessly to find the secret to aging so that they might slow or even stop the process altogether. As it turns out, there is one specific gene that could lead to new discoveries in the anti-aging department. The gene in question is called SIRT6. Its role within the body is to assist in DNA repair through the organization and recruitment of both enzymes and proteins.

The gene itself has a range of potencies. Those with a stronger SIRT6 will live longer, while the opposite is true for those with a weaker version of the same gene. For example, mice have far less potency in their longevity gene than humans, whereas a bowhead whale is thought to have an even stronger SIRT6 than humans because of its impressive lifespan.

Age-related chronic diseases can also be a huge issue during the natural aging cycle, as they severely affect quality of life. The simple act of aging leads to heightened risk for developing chronic diseases such as cancer, cardiovascular disease, and Alzheimer’s disease. Since SIRT6 plays a role in DNA repair, some studies have found that the levels and potency of SIRT6 could be a contributing factor to neurodegenerative age-related disorders such as Alzheimer’s.

Vital RX - brain
Image by Robina Weermeijer on Unsplash: The human brain relies on the longevity gene to support it in the battle against cognitive decline.

Longevity: genetics vs. lifestyle

Genetics play a major role in the aging process, as well as the development of chronic diseases that could lead to increased risk of developing age-related conditions. But lifestyle is also a vital component when understanding how aging works and why not everyone ages at the same succession. 

Things such as the food a person eats, how well and often they exercise, and their avoidance of unhealthy behaviors such as drinking alcohol or smoking cigarettes will all influence the aging process. All these factors are vital when it comes to biological age (how old your body is in the aging process) over chronological age (how many years you have been alive).

Both genetics and lifestyle have an effect on how a person ages, but research has shown that the role of lifestyle is much bigger than genetics. Studies using twins have found that genetics is likely only a small piece of the puzzle when it comes to aging, and that although the SIRT6 gene plays a vital role in the aging process, lifestyle factors are the big thing to watch for when keeping the gene functioning at its best and curbing the aging process for as long as possible.

Can NAD+ reverse aging?

Nicotinamide adenine dinucleotide (NAD+) is found in all cells within the body and is a cofactor in metabolism function. It also contributes to the way the body regulates cellular function by acting as an assistant for proteins. Studies have shown that when levels of NAD+ are depleted, the risk of developing an age-related disease is greatly heightened.

Other studies have begun to research whether the effects of NAD+ could be even greater, in the sense that elevated levels of NAD+ could actually slow the aging process down. More research is needed in this department; studies have only found NAD+ to be effective in rodent trials, and only small-scale human trials have been done, which do not provide sufficient evidence to support that it can slow the aging process.

Synapsins and aging

Neurotransmitters are the messengers that allow the body to communicate on a cellular level. They are chemicals that are released and sent to synapses, the areas where nerve cells connect to receive messages from one another. Synapsins are proteins that help to regulate this process of communication. Aging can have a negative effect on this process, thus leading to synaptic dysfunction.

When neurotransmissions aren’t functioning as they should, problems can arise that lead to lowered cognitive function. This directly affects the aging process, because cognitive decline is a symptom of many age-related diseases.

Vital RX - healthy food
Image by Anna Pelzer on Unsplash: Is it possible to prolong life? A healthy diet is one of the easiest lifestyle habits to adopt to help ‘hack’ the body into staying younger for longer.

Is it possible to prolong life?

Considering lifestyle factors and the longevity gene, it is plausible to prolong life with healthy living practices and supplementation. Beyond the natural lifespan of humans, though, it’s still up for debate whether or not NAD+ or the addition of synapsin can lead to more years of life. They can, however, improve quality of life and help to decrease the risk of developing age-related diseases such as Alzheimer’s.

Featured image by Antevasin Nguyen on Unsplash