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by Dr. Chad Kerksick PhD September 01, 2021 3 min read

I am a strong advocate of teaching ‘calories in vs. calories out’ as the foundation of weight loss and weight gain.

Sure, other factors contribute, but if a coach or trainer does not understand and does not work with a client on understanding their balance between calories in and calories out, the ability for that client to achieve results will most certainly be negatively impacted.

It’s paramount and foundational to success. I’ve even heard some suggest it’s unethical to coach someone on weight loss and not address these things.

Does Your Metabolism Decrease As You Get Older?

Recently, a study was published that evaluated the energy expenditure of 6,421 people (36% male, 64% females) from 29 different countries who ranged in age from 8 days to 95 years (1).

The figure below highlights their findings. You can see a sharp increase in total daily calories (aka, TEE or total energy expenditure) from birth until approximately 20 years of age (black line).

From there, you can see that daily energy expenditure stayed the same from 20 years of age until 60 years of age (red line) before seeing a progressive decline through end of life (purple line).

Energy Expenditure by Age

Here is the part where people may have a hard time swallowing these findings: daily calories burned from 20 years to 60 years old did not change!

How many times have you heard someone say, “My metabolism has slowed down” or “Ever since I got in my 40s…”?

Well, these results tell us that a natural decline in how many calories someone is burning each day is probably not a good place to point to explain a gain in body fat or loss of fitness.

"So Why Have I Gained Weight?"

So, where do we go to find solutions? For me, the answer comes back to behaviors and what has changed since your 20s.

And once I say that, any diet or weight loss coach should immediately start thinking about increasing physical activity and modifying one’s diet.

Certainly, people won’t like to hear this, but if you package this news along with a game plan to see the result they want, progress will occur.

So, what is to blame? In my opinion, nothing magical. Exercise and physical activity gets harder as we get older.

We start to work and that job requires a large time commitment, but it also sometimes includes a commute, traffic delays, getting ready for work, etc.

Many people also start a family and having children creates another time and energy vacuum.

Finally, as you progress into your 40s and 50s, your parents increase in age and now you may need to spend some time and energy helping them.

These are not excuses, but challenges and each person has to figure out how to navigate those challenges.

If there is good news or silver lining, we know that metabolically our bodies are holding up quite well and if you get the lifestyle things in order, the body will still be able to mow through energy.

When is the best time to start?  Right now!  Stop reading and go for a walk, plan a meal, etc. Make it a great day!

Reference

1. Pontzer H, Yamada Y, Sagayama H, Ainslie PN, Andersen LF, Anderson LJ, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808-12.

About the Author

Chad Kerksick is currently an Associate Professor of Exercise Science and Director of the Exercise and Performance Nutrition Laboratory at Lindenwood University. Dr. Kerksick earned his PhD in Exercise, Nutrition, and Preventive Health in 2006 and since that time has worked as a university professor teaching classes and conducting research in areas related to exercise and nutrition. He is currently recognized as an academic fellow, the highest academic honor given by professional societies, of the American College of Sports Medicine (FACSM), National Strength and Conditioning Association (FNSCA), and the International Society of Sports Nutrition (FISSN). He also is certified as a strength and conditioning specialist (CSCS*D), personal trainer (NSCA-CPT*D), and sports nutritionist (CISSN). His laboratory, the Exercise and Performance Nutrition Laboratory (www.lindenwood.edu/EPNL), conducts rigorous, high-quality research investigations devoted to examining the impact of exercise and nutritional interventions of health, performance, and recovery of a large number of populations.

Follow Dr. Kerksick (aka, Dr. Chad) on social at: Facebook: Chad Kerksick • Instagram: @chadkerksick • Twitter: @chadkerksick • Lindenwood EPNL: @LindenwoodEPNL

Dr. Chad Kerksick PhD
Dr. Chad Kerksick PhD