Don't we hear the word 'metabolism' getting thrown around a lot these days?
If yours is too slow, you might gain weight. This is what we know. But what exactly does this all mean? And how does it work?
Technically.... “metabolism” describes all of the biochemical reactions in your body. It dictates how you take in nutrients and oxygen and use them to fuel everything you do and create energy.
Your body is incredible! It has the ability to adjust to tons of environments to grow, heal, and generally stay alive. Without this amazing biochemistry, you would not be possible.
Metabolism includes how the cells in your body:
Handle body functions you can control (e.g. walking, jumping, laughing, etc.).
Handle body functions you can't control (e.g. heart beat, wound healing, processing nutrients & toxins, etc.).
Store excess energy for later.
Combining these processes together into the big picture of your metabolism, I'm sure you can see that sometimes these processes can work too quickly, too slowly, or just right.
This brings us to the “metabolic rate”.
Metabolic rate = how fast your metabolism works.
Metabolic rate is also measured in calories (yup, THOSE calories.)... like how many calories you burn when you're in activity or at rest.
When you eat, calories go to one of three places:
Work (i.e. exercise and other activity).
Heat (i.e. from all those biochemical reactions).
Storage (i.e. extra leftover “unburned” calories stored as fat).
The more calories you burn as work or creating heat, the easier it is to lose weight and keep it off because there will be fewer “leftover” calories to store for later.
There are a couple of different ways to measure metabolic rate-- One is the “resting metabolic rate” (RMR), which is how much energy your body uses when you're not being physically active.
The other is the “total daily energy expenditure” (TDEE) which measures both the resting metabolic rate as well as the energy used for “work” (e.g. physical movement) in a 24-hour period.
What affects your metabolic rate? In two words: a lot!
1. The Thyroid
The biggest factor is the thyroid, that butterfly-shaped gland at the front of your throat that releases hormones & sends the message to your body to “speed up” your metabolism.
The more thyroid hormone there is, the faster things will work, and the more calories you'll burn. When you do things to make your thyroid happy and hum along, your metabolism will too. We'll talk more later about how you can support your thyroid.
But that's not the only thing that affects your metabolic rate.
2. Your weight definitely counts!
Larger people have higher metabolic rates; but your body composition is crucial!
Muscles that actively move and do work need more energy than fat does. So if you have more lean muscle mass, your body will burn more energy and your metabolic rate will naturally be higher... Even when you're simply sitting there - not even working out!
3. Exercises that affect metabolic rate
A major pitfall when people lose weight is that their metabolic rate often slows down too. You don't want to happen! So gradually offsetting that with more muscle mass while losing weight is generally a good idea.
This is why weight training is recommended so often in weight loss programs-- it's because you want muscles to be burning those calories for you.
Aerobic exercise (ex: running, swimming, endurance activities) temporarily increases your metabolic rate. Your muscles are burning fuel to move so they're doing “work”.
4. Foods that affect metabolic rate
Your body can burn calories while it's absorbing, digesting, and metabolizing your food - it's called the “thermic effect of food” (TEF). You can use it to your advantage when you understand how your body metabolizes foods differently.
For example, fats increase your TEF by 0-3%; carbs increase it by 5-10%.
Protein increases it by 15-30%.
By swapping out carbs for lean protein you could increase your metabolic rate.
Another bonus of protein is that your muscles need it to grow, repair, and for recovery. Working out your muscles and feeding them what they want will help you to lose weight and keep it off without going to extremes.
5. Other secrets that affect metabolic rate
There's a mind-body connection! Now, there's tons of research out there that shows the influence of how stress and sleep have on the metabolic rate.
When you are sleep-deprived for as little as a few days, it shows in your metabolic rate because your body is in energy-conservation mode. This also means your body may store energy less efficiently because it's unsure when or if things will return back to normal.
We've only just scratched the surface when it comes to metabolism, since there are countless other factors involved. Now, you've seen how so many different things can work to increase (or decrease) your metabolic rate.