For some reason, I can’t eat a pint of ice cream every night like I could when I was 20! What’s up with that? Well, it has something to do with metabolism. Let’s take a look at what ‘metabolism’ means and how it changes with age.
The word metabolism is derived from the Greek words μετα (meta) and βάλλω (ballo), meaning "to change" or "to throw across". Metabolism is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabolism are:
In order for an organism to live, it must perform these vital functions through specialized enzymes that catalyze each reaction. Enzymes are proteins that lower the activation energy required for a reaction to occur. That means that they make chemical reactions happen faster than they would otherwise. The speed at which a particular enzyme can catalyze a reaction is called its turnover number or kcat. A high kcat means that a lot of product can be made very quickly. Some enzymes have extremely high kcats—on the order of millions per second! Other enzymes are much slower, with kcats on the order of one per second or less. The efficiency with which an enzyme converts substrate to product is called its yield or turnover rate (Km). A high yield means that most of the substrate is converted to product before it has a chance to diffuse away from the active site. If an enzyme has a low Km, that means it can efficiently use substrates present at low concentrations—such as those found inside cells. Allosteric enzymes have two or more binding sites for substrates and/or products and can exist in multiple conformations. These different shapes allow allosteric enzymes to regulate their own activity by modulating how easily their substrates can bind to their active sites
Okay, that’s enough science talk! Let’s look at how metabolism applies to you and your life.
A person's metabolism changes while they age for a variety of reasons. The most common reason is that people naturally become less active as they age. This means that they burn fewer calories and their bodies become more efficient at storing energy, which can lead to weight gain. Additionally, hormone levels change as we age, which can impact our metabolism. For example, thyroid hormone levels decline with age, which can result in a slower metabolism. Finally, our muscle mass decreases with age, and since muscle burns more calories than fat tissue, this also contributes to a lower metabolic rate.
There are several things you can do to offset the impact of these changes and keep your metabolism ticking along nicely as you age. Here’s some of them put together into a nice list for you:
Aging is framed as some terrifying and sad truth that we all must face, but it doesn’t have to be like that! Aging can be fun and genuine and you don’t have to lose yourself in the process.