Metabolism and motivation

Hey there, time traveller!
This article was published 21/08/2021 (1518 days ago), so information in it may no longer be current.

Does your metabolism slow down with age?

You’re probably convinced your metabolism slows down as you get older. Hormonal changes later in life make it worse. And women have it harder than men. Right? Right?

All wrong, according to a paper published recently in Science. The authors evaluated data from 6,421 people from 29 countries, all ages and walks of life, to assess metabolism changes over the years. When all variables were considered, metabolism remained constant from age 20 to 60. There were no differences between men and women.

All of the research centres involved in the project were studying metabolic rates with a method considered the gold standard — measuring calories burned by tracking the amount of carbon dioxide a person exhales during daily activities.

Central to their findings was that metabolism differs for all people across four distinct stages of life.

● There’s infancy, up until age one, when calorie burning is at its peak, accelerating until it is 50 per cent above the adult rate.

● Then, to about age 20, metabolism gradually slows by about three per cent a year.

● From age 20 to 60, it holds steady.

● After age 60, it declines by about 0.7 per cent a year.

Once the researchers controlled for body size and the amount of muscle people have, they found no differences between men and women.

Of course, this data assessed averages. There are genetic and medical factors (and some medications) that make weight loss harder for some people more than others. In those studied, some had metabolic rates 25 per cent below the average for their age and others had rates 25 per cent higher than expected. But these outliers do not change where the majority averaged out.

The researchers also expected the metabolism of adults to start slowing when they were in their 40s or, for women, with the onset of menopause, but researchers found that wasn’t the case. My theory is hormonal changes may result in redistributing body fat to the “menopause muffin” but that’s complete speculation.

In the end, this paper challenges the widespread belief that your metabolism declines throughout your adult life naturally. And while the aging process does introduce its fair share of challenges, a slowed metabolism is more a product of our lifestyle changes over the years than the aging process itself.

You’re under more pressure and time constraints, so you move less and sleep worse. This compounds into craving and eating the wrong foods more often and missing (or never doing) workouts.

At the end of the day, the same methods that work at 20 will work at 60, you’ll just need more diligence later in life to make time for it. In my line of work, I’ve yet to meet someone who can’t lose weight when they follow a plan with persistence and patience.

I’m going to outline a few key things you can do to keep your metabolism revved up as you get older.

1) Your activity level. This is a sneaky one, because you might not actually notice you’re moving less each day.

How active you are each day (including your workouts and your normal activities of daily living) makes up about 10 to 30 per cent of your daily calorie burn.

Very active people can actually burn up to half their daily calories from activity. That’s why a roofer burns a ton more calories than someone who weighs the same but sits at a desk all day.

Studies show that as we get older, we tend to move less, both in terms of exercise and our general daily living.

More than 25 per cent of people over 50 don’t exercise, and by the time we reach 75, that number jumps to more than 35 per cent.

Plus, studies show we also move less in general, burning almost 30 per cent fewer calories through non-exercise activity thermogenesis (NEAT).

While the other components of your metabolism are pretty much set and you can’t do much to change them, especially in the short term, activity — and particularly NEAT — is the one component you do have control over.

Another study comparing women aged 21-35 with women ages 50-72 showed when the older women engaged in regular exercise, their metabolic rate was comparable to the younger women.

The takeaway: start a regular exercise habit you enjoy and can stay consistent with, and find active hobbies. Having these habits in place will set a strong foundation for continued movement as you get older.

2) Muscle loss. This next major cause of a slower metabolism is called sarcopenia — age-related muscle loss.

It’s tied in with your activity level, since being less active is one reason you lose muscle.

On average, adults lose between three and eight per cent of their muscle mass each decade after the age of 30.

One reason this matters — beyond your general strength and ability to move easily — is because muscle burns slightly more calories (even at rest) than fat and it can also be a good “fail safe” when you over-indulge, helping you store excess carbs in the muscle instead of fat cells.

So even if your weight isn’t increasing over the years, your body composition and metabolism at rest is likely getting worse if you aren’t doing things to hold onto that precious muscle.

You can help maintain and build muscle as you age with consistent strength-training workouts: free weights, machines and even some fitness classes (not Zumba, sorry).

The most important part is to create some resistance for your muscles to work against on a regular basis.

The takeaway: get in a few strength-training workouts a week that work all of your body’s major muscle groups.

3) When and what you eat makes a difference!

Eating in a depleted state — such as post-exercise — will mean the calories will be digested differently by your body than a big binge sitting in front of the TV. Your body needs to replenish stored energy in the muscle and liver first, with fat cells a last resort, after hard exercise.

And make sure you eat enough protein. As people get older, they tend to eat less protein. Aim for 20 to 35 per cent of your total daily intake. The thermic effect of the foods you eat is the reason for that. This is the energy expended through digesting and storing food. Carbs, fat, and protein each have different thermic effects, with protein the clear winner with as much as 30 per cent of the calories you eat from protein burned off in the digestive process.

For example, if you eat 100 calories of protein, you’ll only use and absorb about 70-80 calories of it (remember that embarrassing episode of “meat sweats” at the Brazilian barbecue joint? Yeah, this explains it.)

Yes, you may think this is bad news because you have a sedentary job. You sit in a car, at a computer and on a couch for big chunks of the day. But that doesn’t mean you can’t plan your day, take some calls walking around and waking up earlier to squeeze in a workout. We make time for the things that matter and your health should be near the top of that list.

Mitch Calvert is a Winnipeg-based fitness coach for men and women like his former self, struggling to slay their weight-loss demons and become the healthy, fit version they deserve. Visit mitchcalvert.com to grab a free metabolism jumpstart or inquire about his coaching program.