Metabolism 101

We talk about metabolism A LOT. Mostly, we say things like, “I think I have a slow metabolism!”.

This is one of the subjects that deserves a careful review.  When I teach, I say simply that it’s the body processes that keep us living another day.

Some of the functions are in construction (anabolism) like building new cells and some are involved in destruction (catabolism) like removing waste products or making energy.

The body functions that fall under this category include circulation, respiration, cell production, pancreatic manufacture of digestive enzymes, body temperature – continuous processes within the body to live another day. These are INVOLUNTARY functions in the body. We have no control over them.

We measure metabolic rate as calories or Calories or kilocalories or joules (if we’re really science-y). We’ll use “calories”, because it’s an easy and familiar term.

So, the number of calories you burn in a day is primarily those devoted to metabolism. Seems odd because exercise seems so important. But a majority, about 70 percent(!), of the calories you use daily are not under your control.

Briefly, you can imagine that babies have the highest metabolic rate – they are making new cells at a very rapid rate. Growth spurts and pregnancies are other metabolically active periods. I bet you’re already guessing what happens at the other end of the life cycle…

Age, gender, height, weight, genes, hormones (thyroid gland primarily), body and environmental temperature, and health status are primary factors. Saving the best for last – BODY COMPOSITION.

If we consider the body as part fat and part fat-free (muscles, organs, bones) you would be right to guess that fat burns very few calories to live another day compared to fat-free mass which costs us many calories to maintain. The fat-free tissues are busy working and spending calories readily. The fat cells are just sitting around so maintaining them costs very few calories.

So, the only way we can increase our metabolic rate (assuming we love to eat), is to maintain or increase our muscle mass. Exercise does not directly increase metabolism, it INDIRECTLY effects it by creating new cells or maintaining cells devoted to exercise.

Darn, I knew I should have written this blog standing up to be well.



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