Surprising Findings About Age and Metabolism

by Marixie Ann Obsioma
Published on May 18, 2022 and last updated for accuracy on June 10, 2022

You’ve probably heard that as you get older, you can’t continue eating like you did when you were younger.

Because your metabolism often slows down as you get older, you’re more likely to gain weight (1).

Loss of muscle mass, decreased physical activity, and the natural progression of aging metabolic processes are some of the reasons for this phenomenon.

You may, thankfully, fight back against the slowing of your metabolism that comes with advancing age in several different ways.

This article discusses why your metabolism slows down as you get older, as well as some solutions to the problem.

Why Does Your Metabolism Slow Down As You Get Older?

To put it another way, metabolism refers to all the chemical events that occur in the body to help it stay alive (1).

It also plays a role in determining the total number of calories that are burned each day. The greater the speed of your metabolism, the greater the number of calories that you burn (3).

Unfortunately, slowing metabolism is a common observation among the elderly. Even your basal metabolic rate decreases. As you grow older, it is more difficult to keep a healthy weight because you burn less calories.

Four primary components, namely, determine the rate at which your metabolism works:

  • RMR stands for resting metabolic rate, which refers to the number of calories burned while a person is resting or asleep. It is the minimum quantity essential for maintaining your life and bodily functions (2).
  • The thermic effect of food, also known as TEF, refers to the number of calories burned during the process of digesting and absorbing food. TEF is typically equal to ten percent of your total daily calorie expenditure (2).
  • The number of calories burned is a result of participating in physical activity (2).
  • The NEAT (non-exercise activity thermogenesis) talks about the number of calories burned while doing tasks that do not involve physical exercise. These activities include standing, fidgeting, washing dishes, and doing other chores around the house (2).

Your metabolism can also be affected by factors such as your age, height, the amount of muscle mass you have, and even hormones.

Unfortunately, research has shown that as you become older, your metabolism will gradually slow down. A decrease in physical activity and or energy expenditures, a loss in muscle mass, and the natural aging process are some reasons for this phenomenon (3).

Your metabolism is made up of all the different chemical interactions your body goes through to stay alive. Your metabolic rate is determined by several factors, including your resting metabolic rate (RMR), the thermic effect of food (TEF), your level of physical activity, and your level of non-exercise activity thermogenesis (NEAT) (3).

As people get older, they typically become less active.

Your metabolism rate is subject to a large amount of influence from your activity levels.

Activity, which includes exercise and non-exercise, accounts for between 10 and 30 percent of the calories you burn daily. This number can reach as high as 50 percent in persons who engage in much physical activity (4).

NEAT stands for “non-exercise activity thermogenesis,” which refers to burning calories by activities other than exercise. This includes standing, washing dishes, and performing other chores around the house (4).

How many calories do older people burn? Unfortunately, older folks tend to be less active than younger adults and burn fewer calories due to their activity levels.

According to research, more than a quarter of people in the United States aged 50–65 don’t exercise outside work. This rises to more than a third for people older than 75 (4).

According to the findings of other studies, people of advanced age burn approximately 29 percent fewer calories with NEAT.

Keeping up with your average activity level might help prevent this slowed metabolism.

One study involving 65 healthy young people ranging in age from 21 to 35 years and older people from 50 to 72 years found that engaging in regular endurance exercise avoids a slowdown of the metabolism associated with aging (4).

According to research, people tend to become less active as they get older. Your metabolism might dramatically slow down if you do not maintain a healthy activity level because it is responsible for burning 10–30% of the calories you consume daily (4).

The average person loses muscle mass as they get older.

After 30, maintaining muscle mass becomes a problem. A typical adult loses between 3 and 8 percent of their muscular mass per decade.

Studies have shown that by the time a person reaches the age of 80, they have approximately 30 percent less muscle than they did when they were 20 (5).

This age-related loss of muscle mass, also known as sarcopenia, can result in broken bones, decreased strength, and even mortality at an earlier age.

In addition, sarcopenia slows down your metabolism, which is counterintuitive given that having more muscle typically results in a higher resting metabolic rate (5).

According to a study involving 959 participants, persons over the age of 70 had a resting metabolism that was 11 percent slower and had less muscle mass by 20 pounds (9 kg) than people in their forties (5).

One of the reasons why you lose more muscle as you get older is because you become less active, which is one reason your muscle mass is affected by your activity level (5).

The consumption of fewer calories and proteins, as well as a reduction in the production of hormones: estrogen, testosterone, and growth hormone, are two more explanations for this phenomenon (5).

Your resting metabolism will be higher if you have more muscle mass. On the other hand, when people become older, they become less active, their diets alter, and their hormone synthesis slows down, which all contribute to a loss of muscle (5).

The aging process causes a slowing of metabolic processes.

Chemical reactions within the body determine the metabolic resting energy expenditure (RMR).

Your cell’s sodium-potassium pumps and its mitochondria are the two components responsible for driving these events.

While the mitochondria are responsible for the production of energy for your cells, nerve impulses and muscle and cardiac contractions can be generated by the sodium-potassium pumps (5).

According to research, both components become less effective with increasing age, which slows down your metabolism (5).

One study, for instance, compared the rate of sodium-potassium pumps between 27 younger men and 25 older men. The younger men had a faster pace. The pumps were 18 percent slower in older persons, which led to a reduction of 101 calories in daily caloric expenditure (5).

In another study, researchers compared alterations in the mitochondria of 9 younger people (with an average age of 39) to changes in the mitochondria of 40 older adults (average age of 69).

Researchers discovered that older adults have approximately 20% fewer mitochondria than younger adults. In addition, the mitochondria in their cells where the metabolism uses oxygen to generate energy, a process critical to the functioning of the metabolism (6).

The effect of these internal factors on your metabolism rate is less significant when compared to the impact of activity and muscle mass.

Components of cells, such as mitochondria and sodium-potassium pumps, lose some of their effectiveness as we grow older. However, the impact on metabolism is still far smaller than that of activity and muscle loss (5).

How Much Does It Take for Your Metabolism to Slow Down When You Get Older?

Your exercise level, the amount of muscle mass you have, and some other factors contribute to the speed at which your metabolism works. As a direct consequence of this, people’s metabolic rates differ (5).

One study, for instance, compared the RMR of individuals between the ages of 20 and 34, 60 and 74, and over 90. People aged 60–74 burnt approximately 122 fewer calories than the youngest group, and those aged 90 and beyond burned about 422 fewer calories than the youngest group (6).

However, when scientists considered gender differences and the amount of muscle and fat present, they discovered that those aged 60–74 burnt only 24 fewer calories per day on average. In comparison, people above the age of 90 burned 53 fewer calories daily (6).

This demonstrates that keeping your muscle mass as you age is of the utmost importance.

In yet another study, they monitored 516 older adults (aged 60 and over) for twelve years to determine the degree to which their metabolism slowed down each decade. When muscle and fat variations are considered, the average resting calorie burn for women has decreased by 20 over the past decade. In contrast, men’s average resting calorie burn has been reduced by 70 (5).

How Can You Prevent the Normal Age-Related Sluggishness of Your Metabolism?

You can do many things to battle against the natural slowing down of your metabolism that comes with getting older. Here are stuff you can try to prevent your metabolism from slowing down as you age.

1. Give strength training a shot.

Lifting weights or participating in another form of resistance training is an excellent way to prevent slowing the metabolism.

It provides the advantages of exercise while also helping to maintain muscle mass, two aspects influencing the rate at which your metabolism operates.

The resting metabolic rate (RMR) of 13 healthy males between 50 and 65 rose by 7.7 percent after 16 weeks of weight exercise performed three times per week (6).

Another study with 15 participants between the ages of 61 and 77 indicated that six months of weight exercise performed three times per week resulted in a 6.8 percent rise in RMR.

2. Participate in several high-intensity interval training sessions.

Interval training at a high intensity, or HIIT, can help prevent the metabolism from slowing down. It is a method of physical preparation consisting of alternating bouts of strenuous anaerobic activity with brief rest periods.

HIIT also helps you continue to burn calories for a long time after the workout is over. The term for this phenomenon is the “afterburn effect.” This is because your muscles require a more significant amount of energy to recover after exercise (6).

Studies have shown that high-intensity interval training can burn up to 190 calories in the 14 hours following exercise.

Research has shown that high-intensity interval training can help your body create and maintain muscle mass as you age.

3. Get a sufficient amount of sleep.

According to several studies, not getting enough sleep can make your metabolism run more slowly. This effect, however, can be neutralized by getting a sufficient amount of sleep.

According to the findings of one study, the average person’s metabolism is slowed by 2.6 percent for every hour less of sleep they get. Thankfully, a night of extended sleep (about twelve hours) helped to reset the body’s metabolism (6).

It also appears that a lack of quality sleep may contribute to increased muscle loss. Because muscle affects your resting metabolic rate (RMR), decreasing muscle might cause your metabolism to slow down (6).

If you have a hard time staying asleep, try turning off all electronic devices at least one hour before bed. You could also try using a sleep aid like a supplement.

4. Eat more protein-rich foods.

Consuming more foods that are high in protein can assist in the battle against a sluggish metabolism.

This is because your body expends more calories in consuming, absorbing, and digesting food high in protein. The term for this phenomenon is “thermic effect of food” (TEF). Diets high in protein have a greater TEF than foods high in carbohydrates or fat (6).

Studies tell that increasing the amount of protein that makes up 25–30 percent of your daily calories can increase your metabolism by up to 80–100 calories per day, compared to diets that contain less protein.

Combating sarcopenia also requires a sufficient amount of protein. Therefore, a diet high in protein can slow down the aging process of the metabolism by helping preserve muscle (6).

Including a source of protein with each of your meals is a straightforward method for increasing the amount of protein you consume daily.

5. Ensure that you consume an adequate amount of food.

A diet low in calories can cause your metabolism to slow down because it puts your body into “starvation mode.”

When you’re younger, dieting can be helpful, but as you age, it’s more vital to focus on keeping your muscle mass than you did when you were younger.

Additionally, older people typically have a smaller appetite, resulting in a lower calorie intake and a slower metabolism.

If you have trouble getting enough calories in your diet, you should consider eating more frequently but in smaller portions. It is also beneficial to keep high-calorie foods such as cheese and almonds readily available (6).

6. Drink green tea.

A four to five percent rise in metabolism is possible while drinking green tea.

This is because green tea includes plant chemicals and caffeine, which have been demonstrated to enhance your metabolism even while you are at rest.

In a study with ten healthy men, researchers found that giving them green tea three times a day accelerated their metabolism by 4% over a day.

There are many different techniques to deal with the fact that your metabolism will slow down as you get older. This includes weight training and high-intensity interval training, obtaining plenty of rest, eating a diet high in protein and calories, and drinking green tea (6).

The Nutshell Numerous studies have demonstrated that your metabolism naturally slows down as you get older.

Slow metabolism is caused by a combination of factors, including inactivity, the loss of muscular mass, and the natural aging of the body’s constituent parts.

The good news is that numerous strategies are available to combat aging effects that come from a slower metabolism.

This includes lifting weights, engaging in high-intensity interval training, consuming an adequate amount of calories and protein, sleeping a proper amount, and drinking green tea (6).

If you want to help keep your metabolism going strong and perhaps give it a boost, you should try incorporating a few of these tactics into your daily routine.

Interestingly, men and women have become less active over the past decade, resulting in 115 fewer calories burnt from physical exercise. This demonstrates that remaining active as you age is essential to keeping your metabolism in check (6).

One study, however, concluded that there was no variation in RMR amongst women of varying ages. Yet, the oldest group of people in the survey lived exceptionally long lives (over 95 years), which is considered because their metabolisms were more incredible (6).

Takeaway

In a nutshell, the data seems to indicate that the most detrimental influence on your metabolism occurs when you engage in less physical activity and experience a loss of muscle mass.

According to research, the two primary contributors to a slower metabolism as you get older are the loss of muscle mass and an overall reduction in physical activity, hence you experience weight gain. Everything else has a relatively insignificant impact when contrasted with these two criteria (1).

References:

  1. https://www.health.harvard.edu/blog/surprising-findings-about-metabolism-and-age-202110082613#:~:text=Adulthood
  2. https://scitechdaily.com/surprising-findings-show-the-unexpected-ways-metabolism-changes-with-age/
  3. https://www.everydayhealth.com/diet-nutrition/metabolism-may-not-decline-with-age-as-previously-thought/
  4. https://www.nytimes.com/2021/08/12/health/metabolism-weight-aging.html
  5. https://www.nbcnews.com/health/health-news/metabolism-adulthood-does-not-slow-commonly-believed-study-finds-n1276650
  6. https://www.bbc.com/news/health-58186710
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