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Metabolism slower in old age? These are the reasons why!

You’ve probably been told that as you get older, you can’t eat the way you did when you were younger. That’s because your metabolism slows down as you age, making it easier to put on a few extra pounds and harder to get rid of them. Some reasons for this are muscle loss, lack of exercise, and the natural aging of the metabolism. Fortunately, there are many things you can do to counteract these age-related metabolic changes. In this article, you’ll learn why your metabolism slows down as you age and what you can do about it.

What is metabolism actually?

metabolism changes in old age

Simply explained, your metabolism is the set of chemical reactions that keep your body alive. It also determines how many calories you burn per day. The faster your metabolism is, the more calories you burn.

The speed of your metabolism is influenced by four key factors:

  • Resting metabolic rate (RMR): How many calories you burn while you rest or sleep. This is the least amount you need to stay alive and functioning.
  • Thermic effect of food (TEF): How many calories you burn by digesting and absorbing food. TEF is usually 10% of calories burned each day.
  • Exercise: How many calories you burn through exercise.
  • Non-exercise thermogenesis (NEAT): How many calories you burn through non-exercise activities, such as standing, fidgeting, washing dishes, and other household chores.

Other factors that can affect your metabolism include age, height, muscle mass, and hormonal as well as genetic predispositions. Unfortunately, research shows that metabolism slows down as we age. Some reasons for this include lack of exercise, muscle loss and aging of internal organs.

Metabolism slows with age because you move less

metabolism slows down in old age due to less exercise

Research shows that physical activity decreases with age. Less exercise can significantly slow down metabolism, as it is responsible for 10-30% of daily calorie consumption. In very active people, this percentage can be as high as 50%.

Non-exercise thermogenesis (NEAT) is the calories burned by activities other than exercise. This includes activities such as standing, washing dishes and other household chores. Unfortunately, seniors tend to be less physically active and burn fewer calories through exercise. An active lifestyle can prevent these metabolic changes.

A study (1) of 65 healthy young people (21-35 years) and older people (50-72 years) showed that regular endurance training prevents metabolic slowdown in old age.

Not only metabolism, but also muscle mass decreases with age

muscle mass decreases with age

The average adult loses 3-8% of their muscle every decade after 30 years. In fact, research shows that you have about 30% less muscle at age 80 than you did at age 20. This age-related muscle loss is called sarcopenia and can lead to bone fractures, weakness and early death. Sarcopenia also slows metabolism because more muscle increases resting metabolic rate.

A study (2) of 959 people found that people aged 70 years had 9 kg less muscle mass and an 11% slower resting metabolic rate (RMR) than people aged 40 years.

Since muscle mass depends on activity level, lack of exercise is one reason people lose more muscle as they age. Other reasons include lower calorie and protein consumption and reduced production of hormones such as estrogen, testosterone and growth hormone.

Metabolic processes slow down with age

metabolism slows down in old age

How many calories you burn at rest (RMR) , is determined by chemical reactions in your body. Two cellular components that control these reactions are the sodium-potassium pumps and the mitochondria.

The sodium-potassium pumps help generate nerve impulses and muscle and heart contractions, while the mitochondria generate energy for your cells. Research shows that both components lose efficiency with age, slowing metabolism.

metabolism slows down from 45

For example, one study (3) compared the speed of sodium-potassium pumps in 27 younger men and 25 older men. Pumps were 18% slower in older adults, resulting in them burning 101 fewer calories per day.

Another study (4) compared changes in mitochondria between 9 younger adults (average age 39 years) and 40 older adults (average age 69 years). The researchers found that older adults had 20% fewer mitochondria. In addition, their mitochondria were nearly 50% less efficient at using oxygen to produce energy – a process that drives metabolism.

However, compared to physical activity and muscle mass, these internal components have a smaller impact on metabolic rate.

How much does metabolism slow down with age?

how metabolism changes in old age eklärt

How fast your metabolism works depends on your physical activity level, muscle mass, and several other factors. Therefore, metabolic rate varies from person to person.

For example, one study (5) compared the basal metabolic rate of three groups: 20- to 34-year-olds, 60- to 74-year-olds, and over 90-year-olds. Compared with the youngest group, the 60- to 74-year-olds burned about 122 fewer calories, while the over-90s burned about 422 fewer calories. However, after accounting for differences in gender, muscle and fat, the researchers found that the 60- to 74-year-olds burned only 24 fewer calories, while the over-90s burned an average of 53 fewer calories daily. This shows that building and maintaining muscle as we age is incredibly important.

It is important to stay physically active in old age

In another study (6), 516 older adults (over the age of 60) were followed for twelve years to determine how much their metabolism decreased per decade. Taking into account the differences between muscle and fat, women burned 20 fewer calories per decade at rest, while men’s caloric expenditure decreased by 70 calories. Interestingly, both men and women were equally less active, burning 115 fewer calories per decade through activity. This shows that staying physically active as we age is critical to maintaining metabolism.

In short, research seems to show that low physical activity and muscle loss have the greatest negative impact on metabolism.

How can you prevent your metabolism from slowing down as you age?

strength training in old age helps to prevent a slowdown in metabolism

Although metabolism slows down as we age, there are many ways to combat this. Here are 6 of them:

1. try strength training.
This form of exercise improves muscle strength and endurance and can help prevent metabolism slowdown.

2. or with high-intensity interval training.
High-intensity interval training (HIIT) is a training technique that alternates intense anaerobic exercise with short periods of rest.

3. get enough sleep
Research shows that lack of sleep can slow down your metabolism. Fortunately, a restful night’s sleep can reverse this effect.

Eat more protein foods to boost metabolism as you age

4. eat more protein-rich foods.
Eating protein-rich foods can boost metabolism as you age because the body burns more calories when digesting and absorbing them. This is known as the Thermic Effect of Food (TEF). High protein foods have a higher TEF than high carbohydrate and high fat foods.

5. make sure you eat enough
A low-calorie diet can slow metabolism by putting the body in “starvation mode.” Older people also have less appetite, which can reduce calorie intake and slow metabolism. If you have trouble eating enough calories, try eating smaller portions more often. It’s also good to keep high-calorie snacks like cheese and nuts handy.

6. drink green tea
Grüner Tee kann Ihren Stoffwechsel um 4-5 % steigern. Das liegt daran, dass grüner Tee Koffein und Pflanzenstoffe enthält, die nachweislich den Ruhestoffwechsel erhöhen.

metabolism changes with age

1) Studie in The Journal of Clinical Endocrinology & Metabolism / (1997)
2) Studie: Auswirkung der Abnahme der Muskelmasse auf altersbedingte BMR-Veränderungen (1977)
3) Studie: Die Aktivität der Natrium-Kalium-Pumpe trägt zum altersbedingten Rückgang des Ruhestoffwechsels bei (1993)
4) Studie: Oxidative Kapazität und Alterung im menschlichen Muskel (2000)
5) Studie: Altern, Ruhestoffwechsel und oxidative Schäden: Ergebnisse der Louisiana Healthy Aging Study (2009)
6) Studie: Längsschnittliche Veränderungen des Energieverbrauchs in einer älteren deutschen Bevölkerung: ein 12-Jahres-Follow-up (2009)