03 Feb

“I wish I had your metabolism”, “Oh my metabolism isn’t near what it used to be”, sound familiar? A drop in metabolism is one of the most common concerns that are brought up to me as a fitness coach and likely something that you’ve heard countless times as well. Is there any truth to it? Does metabolism change with age? Do different people have different metabolisms? The short answer is yes, but as you will discover in this quick read, its not as clear cut as you might think. Before we dive into this topic, a little bit of background is required. The calories that a person burns in a day can be broken down into 4 main categories: 

  • Resting metabolic rate (RMR) – the energy your body uses just to stay alive (i.e. basic bodily functions, brain functioning, etc.)
  • Exercise activity thermogenesis (EAT) – energy burned from intentional exercise.
  • Non-exercise activity thermogenesis (NEAT) – energy burned from activity that doesn’t pertain to exercise (e.g. fidgeting, walking around the house, doing chores)
  • Thermic effect of food (TEF) – energy required to break down food

 In the discussion of metabolism, we’re mainly referring to resting metabolic rate (RMR). As mentioned before, RMR does change with age but this age but the literature shows that this isn’t actually until age 60! In other words, from age 20-60 there are no significant changes in individuals’ metabolism? (1)  Why then, do we see the general trend of an increase in weight from early to late adulthood? The answer is simply that we move less. We decrease the amount of exercise and discontinue sports and recreation – decreasing exercise activity. We contain ourselves in offices and work from home, decreasing the amount that we inadvertently move throughout the day – decreasing NEAT (which has been associated with increased rates of obesity (2)). The cherry on top is that we are likely the most sleep deprived generation that’s ever existed. With this decrease in sleep comes laziness, sedentary behavior, and a lack of motivation to move! Let me put this into perspective for you. A reduction in the amount of walking around that one does by 20 minutes per day equates to about a 100-calorie reduction in energy expenditure. Over the course of a month, this is 3000 calories – equating to 1 pound in a month. Moving 20 minutes less each day, therefore could lead you to be 12 pounds heavier over the course of just one year! As was mentioned before, RMR also varies between people, with the general trend being the larger an individual and the more muscle mass, the greater their metabolism. Even at the same bodyweight and muscle mass, individuals will have up to a 26% difference in RMR (3). So yes, some people are genetically more fortunate with a “greater metabolism” and each person must consider this when planning any body composition goals. The main takeaway here is that there are variations in everyone’s resting metabolism. This being said, that metabolism likely does not change until around age 60, with changes in weight likely attributable to changes in lifestyle and activity. Regardless, we can hold ourselves accountable and take steps to be proactive about our health. Hiring a trainer is a great way to do so, but by no means the only way. A reminder that just because you were dealt the best genetic cards doesn’t mean that you’re exempt from being healthy! 


  1. Pontzer H, Yamada Y, Sagayama H, Ainslie PN, Andersen LF, Anderson LJ, Arab L, Baddou I, Bedu-Addo K, Blaak EE, Blanc S. Daily energy expenditure through the human life course. Science. 2021 Aug 13;373(6556):808-12.
  2. Chung N, Park MY, Kim J, Park HY, Hwang H, Lee CH, Han JS, So J, Park J, Lim K. Non-exercise activity thermogenesis (NEAT): a component of total daily energy expenditure. Journal of exercise nutrition & biochemistry. 2018 Jun 6;22(2):23.
  3. Johnstone AM, Murison SD, Duncan JS, Rance KA, Speakman JR. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. The American journal of clinical nutrition. 2005 Nov 1;82(5):941-8.
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