Metabolism and You

Most of us believe that our metabolism is at its peak during our teenage years and early twenties. Who can forget getting ready to go out at 10:00 p.m. and the late nights out with friends? Unfortunately, as we age, that 10:00 p.m. turns into getting ready for bed instead of a nighttime adventure.

We believe that certain life milestones affect our metabolism – puberty, menopause, and middle age – the reason behind our drive and ability to enjoy those late nights in our younger years. However, it is just not true.

Researchers found that metabolism increases as babies grow and peaks around age 1, when babies burn calories 50 percent faster than adults, almost triple the rate at birth. Metabolism then gradually declines roughly 3 percent throughout your childhood and teen years. Once you reach adulthood, it remains consistently level (depending on your activity and diet.) Then, it starts its decline once again during senior years.

With this in mind, your “middle-aged spread” is strictly due to your lifestyle, not your metabolism. As we get bigger, we burn more energy – there are more cells to fuel, and we need more calories. Our role in deciding how our metabolism will react is strictly up to us – the food we eat and the exercise we do.

What is a Metabolism?

Photo: Sara Jobling

Simply put, your metabolism is all the chemical reactions that keep your body alive.  It is a complex process that combines oxygen and calories to create and release energy that fuels your body’s functions.  Your metabolism never stops, even when your body is at rest.  It provides the energy that helps you breathe, allows your blood to circulate, and regulates your body’s temperature.  It grows and repairs damaged cells and manages your hormone levels.  While eating, it helps digest your food. 

Why the change then? If metabolism helps with essential functions like breathing, why would it change?    The speed of your metabolism is affected by four key factors1 that change as we age for various reasons.

Resting Metabolic Rate (RMR)

RMR determines how many calories you burn while resting or asleep and is the least amount of energy needed to keep you alive and functioning.  Two cellular components drive RMR – mitochondria and sodium-potassium pumps.  Mitochondria is a biochemical process in our bodies where respiration and energy production occur.  Older adults have 20% fewer mitochondria, and those they did have were 50% less efficient at using oxygen to create energy.  Sodium-potassium pumps found in our cellular membranes help generate sodium ions.  Sodium ions are essential for generating action potentials – a rapid sequence of changes across a membrane – in nervous and cardiac tissue.  They act to regulate blood volume and blood pressure in your body.

Thermic Effect of Food (TEF)

TEF is a thermogenetic process that defines the number of calories burned through digestion and absorption of food (usually 10% of your daily caloric intake.)  Some calories you eat are digested, absorbed, and metabolized.  Others are stored, and some burn off as heat. By consuming calories, you increase the rate at which your body burns calories.  The key, however, is what you eat.  You want to ensure the ratio does not lean towards fatty foods that turn into stored calories.


Exercise is the level of calories burned through physical activity. 


Non-exercise activity thermogenesis or “NEAT” includes caloric expenditure with activities such as standing or performing household chores.

What Affects Our Metabolisms?

Your metabolic processes are necessary to maintain your body and your living state. Along with genetics, our metabolic rate determines our body’s shape. Many factors affect how your metabolism will work. First, our muscle mass – it takes much more energy to build and maintain muscle than fat. The more muscle mass you have, the faster your metabolism. Now, this does not mean you should go out and get a body builder’s physique but instead that you ensure your body fat measurement (BMI) is low.

Your age and genetics also play a role in metabolic rates. As we get older, we lose muscle mass, slowing down our metabolism. Women naturally also have less muscle mass than their male counterparts. Finally, let’s not forget about genetics. The genes you inherit from your parents play a role in your size and ability to build muscle mass.

Perhaps one of the most critical factors affecting metabolism is physical activity. As you move, you burn more calories than if you are sedentary.  Burning calories ensures your metabolism remains high or fast, resulting in more calories burned even while at rest.  A high metabolism allows you to eat more without gaining weight. Now, if that’s not reason enough to exercise, I don’t know what is.

Although I don’t recommend it, nicotine also speeds up your metabolism. Smoking, however, has serious health consequences that far outweigh any benefit you get from burning a few extra calories.

Boosting Metabolism with Food

Food, glorious food. No wonder we love to eat. It fuels our bodies in ways we never thought. Maintaining our muscle mass as we age is essential, and the good news is that there are foods that will help you do this. Your first friend is protein. Protein helps you burn more calories around the clock, and burning more calories leads to a higher metabolic rate. Protein is found in foods like meat, fish, eggs, nuts, and seeds. Beans and legumes like lentils, peas, chickpeas, black beans, and peanuts are all naturally high in proteins. This high protein content requires your body to burn more calories for digestion.

After protein, mineral-rich foods, specifically those high in iron and selenium, should be on your list. Iron is a significant component in hemoglobin, a protein in red blood cells that carries oxygen from your lungs to all body parts. Without enough iron, there are not enough red blood cells to transport oxygen, which leads to fatigue. Selenium helps your thyroid gland, which regulates your metabolism to function properly. Foods you should be looking for once again include meat, seafood, nuts, and seeds.

Certain foods that are neither high in proteins nor minerals are better than others in increasing your metabolic rate. This list includes chili peppers with a high level of capsaicin, a neuropeptide-active agent that can boost metabolism, amongst a host of other benefits. Surprisingly, coffee and tea are also on this list. Caffeine in coffee and tea raises the blood levels of epinephrine (adrenaline) and promotes the release of fatty acids from fat tissues. Teas also have a type of flavonoid called catechin that helps break down body fats quicker.

Certain spices are also better for your metabolism. Ginger or gingerols help digest food faster, stimulate the body to speed up food digestion in the colon, and have an anti-obesity effect. Studies have suggested ginger may boost your metabolism by as much as 20% for about three hours after a meal. Cayenne, which is basically the spice form of chili peppers, helps burn fat and increase your metabolism. Cumin is the little spice that could. It contains a unique active ingredient – thymoquinone – a naturally occurring chemical that targets free radicals in your body. Not only does it cleanse your body of toxins, but it helps burn off excess body fat.  

Ensuring You Maintain a Healthy Metabolism

We already know that you are what you eat, but did you know that you should eat to maintain a healthy metabolism?  Skipping meals is not a good thing for your metabolism.  If you over-restrict your caloric intake, your body starts to break down muscle for energy.  Loss of muscle mass slows down your metabolism.  Fuel your metabolism with fresh fruits and vegetables, lean proteins, healthy carbohydrates and fats, and healthy spices.  Not only does this ensure your metabolism stays healthy, but it will also help maintain a healthy body weight.

Ensure that you are well hydrated.  According to one review, drinking just two glasses of water (17 ounces/500 mL) will increase your RMR by 30% for one hour2.  In addition to water, get plenty of sleep.  Lack of sleep affects the body’s levels of ghrelin, the hunger hormone, and leptin, the hormone that controls fullness, in addition to negatively affecting the hormones that regulate metabolism3.  Stand whenever you can – long periods of sitting burn fewer calories.  (If you work in an office-type environment, stand up as often as possible during the day.) Finally, exercise – build your muscle mass with weight-resistance type exercises.  If you are not the fitness type, visit your local mall and walk around for an hour or two. Any activity is better than no activity at all. 

It’s All Sunshine and Roses from Here

I used to think I could blame age on my increasing aches, pains, and waistline. It turns out it’s just my metabolism. The good news is that you can fix your metabolism. The bad news is it may take time and effort. Following a nutritious, well-balanced eating plan is the first step. Physical activity is the next—time to visit my local mall for some weight-lifting—shopping bags, not dumbbells.





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