Metabolism involves the body's conversion of what you eat and drink into energy. It powers all the bodily processes from breathing to moving, to repairing cells and regulating body temperature. It's firing all the time––when you're exercising at the gym, sitting at your desk, and even when you're sleeping. But it's not always functioning at the same rate because it signals to your body to use more or less energy at different times, for a range of reasons.1
When looking at someone's metabolism, doctors consider a person's basal metabolic rate (BMR), which is the average daily amount of energy (calories) that is used by the body when it is at rest.1b
At rest, the body uses energy to maintain basic processes like:
The amount of energy that your body uses depends on factors like:
Total energy expenditure (TEE) is a person’s BMR plus the energy needed to digest food and move throughout their day.3
Some people have metabolic disorders that can affect their weight. A metabolic disorder is a condition related to how your body uses energy to function. Some of these are mostly rare genetic conditions, but the vast majority of metabolic disorders are acquired later in life (such as Type 2 diabetes and thyroid conditions).1
While your metabolism will regulate itself to meet your body’s individual needs, in general:
It’s tempting to think about metabolism as something that can be easily manipulated to help you shed pounds, but it’s a complex system that goes beyond how many calories you burn, and metabolism alone is not responsible for weight loss or weight gain.1
Fact: A person’s metabolism is partly genetic and it’s largely outside of their control. The internet and social media are packed with suggestion for revving up your metabolism, particularly with exercise, but how much these hacks can truly help is debatable. In fact, the number of calories burned through physical activity is often overestimated.2 A 160-pound person walking at a pace of 6.4 kph (4.0 miles per hour) will burn about 383 calories. For comparison purposes, a breakfast bagel with ham, egg, and cheese provides about 483 calories of energy, offsetting the calories that were burned through 10,000 steps.2b Physical activity is highly recommended for a number of health reasons, but it needs to be combined with reduced intake of calories through healthy eating if weight loss is a goal.2c
Fact: You’ve probably heard that metabolism slows to a standstill in midlife. While it’s true that age can be a factor in packing on extra pounds in your forties and beyond, it’s not typically due to a dipping metabolism. New studies show that a person’s metabolic rate actually stays relatively steady between ages 20 and 60 and starts to decline after that. Between ages 40 to 60, weight gain is more likely caused by lifestyle changes like canceling your gym membership, skipping the walk to work, and differences in your diet at this life stage.3
Fact: It’s true that adding more sriracha to your burrito and wasabi to your sushi will heat up more than just your mouth. Spicy foods, particularly ones with jalapeno and other chili peppers, stimulate the sympathetic nervous system, increasing your body temperature (that’s why hot wings make you sweat!) and, in turn, your body’s energy expenditure. Studies have found that eating spicy foods can give your metabolism a small boost, but it’s only by an estimated five to eight percent, while you’re enjoying those meals. Researchers say the slight increase is unlikely to have a meaningful impact on long-term weight control.4
Fact: The opposite may be true. Larger people expend more calories than lean people during everyday activities, in part because it takes more effort to move around. But some people with obesity tend to be more sedentary due to their size, which means they may burn fewer calories in total over the course of a day.2
Fact: There are many products in the natural health and vitamin aisles that claim to “melt fat” and “boost metabolism.” Science does not support these claims—there is no magic pill to increase metabolism, and when misused, these products can pose serious risks to your health. But, even if these products contribute very little to weight loss, some natural health products may be safe and effective when used as part of a weight management program.5 Some key nutrients including B vitamins, vitamin D, vitamin C, iron, and magnesium are important for metabolic health.6 And some of these supplements also include green tea, which contains antioxidants that may support metabolic functions, too. (More on green tea below.) Ask your Rexall pharmacist if these products might be right for you.
Fact: Nibbling on smaller amounts of food more frequently can prevent dips in energy, stabilize blood sugar levels, and keep you feeling full. Swapping a typical breakfast, lunch, and dinner for multiple mini meals throughout the day will not affect your body’s metabolism, though. What’s worse, it can backfire as a weight-loss strategy because eating more often can easily turn into overeating, if you end up grazing all day long.7
Fact: Cardio workouts can play an important role in contributing to overall health. Burning calories is one of the main outcomes of metabolism, and aerobic workouts will get your metabolism revving during and immediately after your bike ride, brisk walk, or Zumba class. However, for meaningful weight loss to occur, a reduction in calorie intake is also needed. Don’t forget about other types of exercise that will support your metabolism and overall health in other ways. Strength-training workouts like lifting weights or a HIIT class will help you to build muscle, and more muscle composition will increase your body’s resting metabolic rate. Ultimately though, a well-rounded movement plan includes both aerobic and strength workouts to maintain strong muscles, bones, and to keep off extra weight.8 Health Canada recommends that adults ages 18 to 64 do a variety of physical activities adding up to at least 150 minutes per week and do muscle-strengthening activities at least twice per week.9
Fact: Studies have shown the compounds in green tea may support metabolic regulation, but so far, the effect seems to be negligible, and researchers can’t say how much you’d need to drink for it to increase your metabolic rate.10
Fact: Your mother may have told you that you need a nutritious meal to start your day, but research shows that most adults don’t require a hearty breakfast. A number of studies on intermittent fasting (an eating pattern where you cycle through periods of voluntary fasting) have shown that extending the overnight fast is linked to weight loss. A daily 16-hour fast is a common method of the many variations of intermittent fasting protocols. Intermittent fasting allows blood sugar and insulin levels to decrease so that fat stores need to be used for energy. Skipping the early meal in favour of a nutritious early lunch may support a successful weight loss journey.11 If you have a medical condition such as diabetes, be sure to consult with a health professional before starting on an intermittent fasting plan.
Fact: Weight gain, or a plateau in weight loss, is often blamed on having a sluggish metabolism. Regardless of whether your metabolism is speedy or slow, your body is designed to store excess energy in fat cells. A person with a slow metabolism will burn fewer calories throughout their day, including while sleeping, working out, and everywhere in between. Although this can make the process of shedding pounds more challenging, it is still possible to manage a healthy weight by focusing on eating less and moving more.12
Be sure to stop by and speak with your Rexall pharmacist if you have any questions about how your metabolism is impacting your weight management, and what you can do to support a healthy body weight.
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