Common knowledge has always been that your metabolism decreases with age. But new scientific study’s published on Science.com and reviewed on Harvard Medical School’s website cast doubt on this belief.
We do know that growth hormone decreases over time, your hormones (testosterone, estrogen, progesterone, etc.) change as you age, and conventional wisdom and science has always been that your metabolism slows down with age, and weight gain is almost inevitable.
But new science is casting doubt over this firmly held belief. Take a look at what some new scientific studies have found.
What does this mean to firmly held beliefs?
Do you need to dig deeper to find the truth?
Or do you need to reassess what you have held true for so long and look at this with an open mind?
Surprising Findings About Metabolism and Age
A recent study published in Science and reviewed on Harvard Medical School claims, “results strongly suggest that we may no longer be able to blame weight gain in middle age (20-60 years old) on a slowed metabolism.” The study goes on to state that metabolism accelerates rapidly up to about 1 year old, slowly declines until about 20 years old, remains constant until about 60 years old, and then declines the rest of our life.
This sure has me reassessing my claims about my metabolism falling off a cliff when I hit 40!
Okay…so I have a few questions I would like answers to then:
- What does this study define as “metabolism?”
- Why am I gaining weight so much easier in my 30’s, 40’s, 50’s, etc… than I did in my teens and 20’s?
- What can I do to increase my metabolism, lose weight, and feel great?
What is metabolism?
When you talk about your metabolism you are generally referring to your basil metabolic rate (BMR). BRM is also used interchangeably with resting metabolic rate (RMR) – or the number of calories needed for your body to function at rest. More simply put, this is the number of calories you need to consume each day to neither gain or lose weight.
Other factors play a role in your BMR and total daily calorie needs such as genetics, activity level, and body composition (muscle vs fat ratio) to name a few. Read on to learn how much genetics, muscle, and exercise play in effecting metabolic rate.
Why am I gaining weight so much easier now that I am no longer in my 20’s?
There could be multiple things going on, but the most common change in your body that makes you gain weight as you age is the loss of lean mass (muscle). Since metabolism is affected by the amount of lean mass you have, it goes down when your lean mass goes down.
When you are a child, even through college and a few years beyond, you are constantly on the go. Playing sports, riding bikes, walking to classes, etc… When you are young you are moving and using our muscles. Moving around helps you maintain your muscle mass. Once you get older and get a desk job, your lifestyle can become more sedentary, which results in less muscles being used so they start to wither away. Throw in having kids, lack of sleep, and busy stressful schedules and you have a perfect storm of muscle decaying impacts.
Couple this with the popular method to lose weight quickly by decreasing calories (without getting enough protein to feed your muscles) and doing large amounts of cardio and you have a muscle eroding perfect storm.
It only makes sense that over 10-15 years, crash diets 3 times per year, crazy stressful lives, and a more sedentary work life that we lose muscle and our metabolism slows down and we gain weight.
How do you calculate how many calories you need each day?
The first step in controlling weight is to figure out how many calories you need to consume each day. Generally speaking, it is fairly easy to calculate your daily caloric needs. Check out this resource by Healthline to calculate your daily calorie needs. I am sure there is also a website that does this for you too!
Once you have this number you can begin testing if it works for you or not based on your goals, and we highly recommend you speak with your doctor, a registered dietitian, or nutritionist before making changes to your diet or calorie intake.
How do you naturally raise your metabolism?
Before jumping into what actions to take to raise your metabolism, we looked at what factors impact your metabolism. Here is what Science Direct found:
- Body Composition plays the biggest role in metabolic rate with roughly 80% of the variability in BMR (basil metabolic rate) for individual differences explained by how much lean and fat tissue an individual has. Lean tissue is muscle, bone, connective tissue, etc..
- Genetics play a much smaller role than conventional wisdom suggests accounting for roughly 10% variability for individual differences.
- Other factors like obesity, starvation or anorexia, hypogonadism, adrenal insufficiency, Cushing’s syndrome, immobilization, and sedative drugs are known to decrease BMR.
The other big factors are gender and overall body size (height). Not much you can do to impact genetics, gender or height, so let’s dig into Body Composition because this is the single biggest factor you can influence to increase your metabolism.
Muscle accounts for roughly 25% of your RMR, and jumps to 80-90% during exercise. On the other hand, adipose tissue (also known as fat) is a minor contributor to RMR. In fact, muscle mass is roughly 4 times more metabolic than fat.
So, the goal is to lower your fat and increase your muscle if you want to increase your metabolism.
Ready to start losing fat and gaining muscle? Here are 4 blogs we wrote on the best ways start your health journey.
- LOSE WEIGHT WITHOUT BEING HUNGRY – THROUGH A REAL, WHOLE FOOD DIET: eating a healthy, balanced diet consisting primarily of whole foods in the form of fruits, vegetables, lean protein, and whole grains
- HOW TO GET A TONED & LEAN BODY AT ANY AGE: maintaining an active lifestyle with a goal of at least 150 minutes of physical activity a week, including strength training to increase or maintain lean muscle mass
- THE IMPORTANCE OF SLEEP ON YOUR HEALTH: getting adequate rest, which for most individuals is seven to eight hours of sleep daily
- FEELING STRESSED? YOU'RE NOT ALONE: managing stress through mindfulness, meditation, or other relaxing activities.
The last thing we want to mention is that we need to drop the “all or nothing” mentally that surrounds weight loss. Sustainable methods create sustainable results. I like to remind people that it took years to get to the place you are and there is no quick fix. Making small consistent changes over months that become part of a new healthier lifestyle is how you achieve lasting weight loss and improved health. Don’t rush the process. Trust the process!
Live for it.
Duke
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References:
- https://www.health.harvard.edu/blog/surprising-findings-about-metabolism-and-age-202110082613
- https://www.science.org/doi/10.1126/science.abe5017
- https://www.healthline.com/health/what-is-basal-metabolic-rate#estimating-bmr
- https://www.sciencedirect.com/topics/immunology-and-microbiology/basal-metabolic-rate
- https://www.unm.edu/~lkravitz/Article%20folder/metabolismcontroversy.html#:~:text=In%20fact%2C%20scientific%20estimation%20of,about%2020%25%20body%20fat).