Metabolism: What is it exactly and what can I do to increase mine?

Metabolism can be defined as the process by which our bodies convert what we eat and drink into the energy we need to fuel all the basic automatic processes like breathing and cell division as well as the energy needed to walk, run and all the other activities we choose to do. Metabolism tends to slow with age making it easier to add on a few pounds and difficult to get them back off again. But is this slow down due mostly to the normal aging process or is it more closely related to the lifestyle changes we make as we age?

There are four components of metabolism which determines the rate at which we burn calories and there are five lifestyle choices we make that influence those components and help determine if our calorie burn rate is more like a shiny new Ferrari or a 68 Volkswagen bus. If you want to learn a little something about metabolism and your body read on; if not, feel free to skip to the summary at the bottom of the article for the five choices you can make right now to speed up your metabolism.

In this section, I am going to break down what metabolism is and what we can do to influence how fast or slow we burn calories.

Resting Metabolic Rate (RMR)

This is how many calories you burn while resting or asleep. It is the lowest amount of metabolic activity to keep you alive. Many things contribute to how fast or slow this is such as your genes, hormones, diet composition and environmental impacts such as sleep and stress. This component is the one that is the most affected by aging and one article went as far as to attribute the slow down to the "aging of our internal components". WHAT?!?! Current research points to other reasons for metabolism slow down as being larger factors but yes, there is some component of our bodies becoming less efficient as we age as a reason for a slowdown in RMR. All of us over 40 know that at some point a switch got flipped while we slept because one day we realized we just couldn't bounce back the way we used to from that hard workout, or a long day of yard work or even a night out with friends. But to blame that extra 20 pounds on your frame or a new medical diagnosis on "a normal part of aging" is just misdirecting the blame. A big part of how fast your RMR is depends on how much muscle you have. We will discuss muscle mass more in a minute, but one interesting piece of research found that after accounting for differences in gender, muscle and fat, people aged 60-74 burned only 24 fewer calories per day than those aged 20-34.1

So with that in mind, age doesn't play that big of a factor in the slowing down of your metabolism but decreasing muscle mass as we age does.

Thermic Effect of Food (TEF)

This is a fancy term for how many calories are burned during the digesting, absorbing, transporting and storing of the food and beverages you drink. This is where diet plays a role in your metabolism.2,3

  • Protein

It has the highest TEF, so including adequate protein, every time you eat means more of the calories you ingested will be used digesting, absorbing, transporting and storing. Protein also keeps you fuller longer than carbohydrates so if you make a point to eat high-quality protein, you are less likely to overeat. The exception to this is if you are one of those people who inhales their food or mindlessly eats. If you are an inhaler - slow down, we are no longer scavengers. No one is going to take the food off of your plate. It takes approximately 20 minutes from your first bite of food for your brain to start releasing the chemical signals to tell you to stop eating. I know several people who pride themselves on their ability to eat quickly and I've witnessed them eat full, huge meals in under 15 minutes but then after 45 minutes they are miserably over full. Maybe you don't realize you are eating too quickly. Time yourself next time and see. Or maybe you mindlessly eat in front of the tv, at work, or whatever. You are eating out of habit or boredom and not hunger. When we do that, we can easily overeat hundreds of calories each day. Our protein needs also increase as we age but we tend to eat less of it for some reason. This is where making conscious choices makes a huge difference. Getting enough protein as we age may slow some of that "aging of our internal components". Eating adequate protein also helps our bodies hold onto existing muscle when we are restricting calories. Eating protein will make sure that the weight you are trying to lose is actually fat loss and not muscle. Have I convinced you to eat more protein yet?

  • Eat real food.

Sounds pretty simple, doesn't it? There is even a # for it. #JERF (Just Eat Real Food). Your body will generally burn more calories digesting real food, it will absorb the nutrients better and it will have fewer toxins to rid itself of if you stick to foods that your body actually recognizes as food. If the label has a ton of ingredients or words that you can't pronounce, then your body will probably not recognize it as food.

  • Drink more water.

Studies have shown that drinking 17 ounces of water will increase RMR by 10-30% for the next hour!4 Drinking cold water may increase that percentage because your body has to use energy to heat the cold water up to body temp. Water also fills you up, so you tend to eat less. Did you know that when you "feel" hungry you may actually be thirsty? It may be an evolutionary throw back our brain does to make sure we don't starve, but many times we are not hungry, just thirsty. Next time you feel hungry, drink some cold water and wait 30 minutes to see if you are still hungry before eating that snack. Individual water needs vary, but a good rule of thumb is to take your body weight in pounds and then drink half of that in ounces per day. So, a 140-pound person would need to drink 70 ounces of water per day at a minimum. Needs will increase with exercise, climate, illness, etc. If plain water is not your thing, you could jazz it up with fresh lemon, lime or oranges. You could drink herbal teas or green tea - just lay off the sweeteners. There are also healthy drink mix options out there now, just read the labels and stay away from the chemically ones. Chemicals are gross. Don't drink chemicals.

Non-Exercise Activity Thermogenesis (NEAT)

This is how many calories you burn through non-exercise activities like standing, fidgeting, washing dishes, etc. In other words, MOVE MORE. Sitting still burns fewer calories than standing still, so much so that some health commentators are calling sitting "the new smoking". Manufacturers have caught on and are making it easier to stand at work. Have you seen a standing desk? Sitting burns fewer calories because it takes fewer muscles to sit than to stand. To stand you have to engage your abdominals, glutes and leg muscles. Few of these muscle groups get any use while sitting.


This piece takes into account how many calories you burn during exercise. This is where you build the muscle mass to keep your RMR humming along while you sleep. Muscle mass tends to decrease as we age but it isn't because "that's just what happens as we age". It happens because we tend to stop exercising as much and we tend to eat less protein. See how all of this fits together? One study showed that regular exercise prevents metabolism from slowing down in healthy young people as well as older people (50-72 years).5

There are two main parts of exercise that you want to focus on:

  • Increasing your heart rate:

Always check with your doctor, but if you are healthy enough, getting your heart rate up for short amounts of time will increase calorie burn and increase overall heart health. One way to do this is with HIIT workouts. HIIT stands for High Intensity Interval Training. You may have heard about these workouts because they are currently all the rage and with good reason - they work! But if you are new to exercising, your HIIT will look vastly different than someone who has been regularly working out. Essentially you want to work hard for as long as you can or up to 30 seconds and then recover for up to 2 minutes before working again. You want to aim for 4-6 work and recovery sessions. That could mean walking or running as fast as you can for your work and then walk at a slower pace for your recovery. You just don't want to take the whole 2 minutes if you don't have to do so. You are aiming to get back to the "work" part as quickly as you can. You could do this with biking, swimming or even jumping jacks. You are only limited by your imagination.

  • Lift heavy things:

Muscle burns more calories than fat - period. So, the more muscle you have, the higher your RMR. You could take a weightlifting class at your local gym, maybe try CrossFit type workout or if either of those sound intimidating, do bodyweight exercises at home. Things like squats and push-ups can be done with no equipment. There are tons of videos online to show you modifications if that seems too difficult. If you have small children at home, you can squat with them in your arms for added resistance and picking them up and lifting them in the air is a wonderful way to work your arms and abdominals. Use your imagination!

The last lifestyle choice that makes a huge impact on your metabolism is sleep. Everyone's sleep needs are different, and it is now recognized that 8 hours is no longer the gold standard, but a vast majority of us need somewhere between 7-9 hours a night. Even that changes day to day due to stress, exercise, diet and if we are fighting an illness just to name a few. Modern society places very little emphasis on getting good sleep, so it can be hard to know how much we need. Lack of sleep has been linked to a major increase in the risk of obesity.6,7 Lack of sleep has also been linked to an increase in chronic disease.8 Sleep is when your body repairs all the damage that happened during the day. It was busy working, digesting and exercising, it didn't have time to repair. Short change the repair your body needs and you will decrease how well your body functions the next day, whether you feel it or not. Over time the sleep deficit builds up and things start to go wrong. And guess what? It also seems that poor sleep may increase muscle loss.9 And you know by now that decreased muscle mass means decreased RMR.


There are 5 choices you can make every day to increase your metabolism and burn more calories:

1. Eat real food: Make sure if what you are eating has labels that you can read them. NO CHEMICAL food! Eat more food without labels. Eat more protein. We tend to minimize how much protein we actually need.

2. Drink more water: Aim for half your body weight in ounces drank per day. Cold water may be even more beneficial because your body has to burn energy to raise the temperature.

3. Move more: Any kind of movement is beneficial, even choosing to stand over sitting. Getting your heart rate up with a HIIT workout can really increase your resting metabolic rate.

4. Increase your muscle mass: Lift heavy things, even if that is your own body weight. The only way to increase muscle size is to use those muscles, so do squats, push-ups, lift your kids or grandkids as high as you can!

5. Get your sleep: Most people need 7-9 hours a night. Make it a priority so your body can rest and repair the way nature intended.

I hope you found this helpful! If doing all this at once seems overwhelming, pick one of the five and start chipping away at it. You've got this!