Hey Fit Family! 

There are so many lies that swirl around the word Metabolism. 

I hate these lies because they generally just leave people frustrated, angry, and confused without a way to take action. 

Perhaps, one of the most unhelpful of these myths has just been debunked by the largest metabolism study to date.

A new study in Science found that in both men and women total calories burned in the day does not seem to go down until the age of 60! 

And, even after 60 the decrease in the amount of calories we burn can likely be significantly blunted by staying active and maintaining our muscle mass. 

Another key finding from this study that has now been found on multiple occasions is that whether someone was male or female had no independent effect on the number of calories they burned when controlling for body composition. 

Given that on average men do have more fat-free mass and are 15 to 20% bigger than women they will still on average burn more calories per day, but the differences look to be due primarily to body composition. 

Thus, the number one determinant of your resting metabolic rate and the total amount of calories you burn in a day seems to be the amount of Fat-Free Mass on your frame! 

When it comes to the word Metabolism focus on Movement and Muscle, not unhelpful fatalistic narratives that give you no way to move forward and leave you blaming yourself for things outside of your control. 

We vote with our actions today and with lifelong physical activity we are capable of preserving our muscle mass, bone density, strength, and independence into old age! After 30, if we do not exercise we will lose an average of 3-8% of our muscle mass per decade and this accelerates to possibly more than 10% decade after the age of 50! 

This loss of muscle will likely lower the calories we burn in the day and has been identified as an independent predictor of hospitalization, disability, and death. BUT, physical activity and preserving muscle mass look to be protective against chronic disease and death for everyone. None of this is guaranteed. 

This is why we recommend maintaining higher levels of daily movement (>8,000 steps) and some form of resistance training or exercise at least twice per week...FOREVER. Because if we don’t use it…we lose it.

#GIVEAFIT

REFERENCES:

1. Pontzer, H., et al., Daily energy expenditure through the human life course. Science, 2021. 373(6556): p. 808-812.

2. Pontzer, H., et al., Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans. Curr Biol, 2016. 26(3): p. 410-7.

3. Hopkins, M., et al., Modelling the associations between fat-free mass, resting metabolic rate and energy intake in the context of total energy balance. Int J Obes (Lond), 2016. 40(2): p. 312-8.

4. Careau, V., et al., Energy compensation and adiposity in humans. Current Biology, 2021.

5. Wroblewski, A.P., et al., Chronic exercise preserves lean muscle mass in masters athletes. Phys Sportsmed, 2011. 39(3): p. 172-8.

6. Mitchell, W.K., et al., Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review. Front Physiol, 2012. 3: p. 260.

7. Abramowitz, M.K., et al., Muscle mass, BMI, and mortality among adults in the United States: A population-based cohort study. PLoS One, 2018. 13(4): p. e0194697.

8. Valenzuela, P.L., et al., Joint association of physical activity and body mass index with cardiovascular risk: a nationwide population-based cross-sectional study. Eur J Prev Cardiol, 2021.

9. Srikanthan, P., et al., Sex Differences in the Association of Body Composition and Cardiovascular Mortality. J Am Heart Assoc, 2021. 10(5): p. e017511.

10. Tarp, J., et al., Fitness, Fatness, and Mortality in Men and Women From the UK Biobank: Prospective Cohort Study. J Am Heart Assoc, 2021. 10(6): p. e019605.

11. Volpi, E., R. Nazemi, and S. Fujita, Muscle tissue changes with aging. Curr Opin Clin Nutr Metab Care, 2004. 7(4): p. 405-10.