In most people’s minds, a fast metabolism translates to thinness and easy weight loss. That’s why there are countless teas, pills and powders that claim to boost metabolism, and just as many media headlines pertaining to the topic. I frequently talk clients through misconceptions about metabolism and the belief that "mine must be slow" if you are attempting to change your weight. (The truth is more likely to be that the calories they are consuming outweigh their body’s needs.)
With all of this conflicting noise out there, how can you really know what to believe? In this post, I'm breaking down the top five metabolism myths for you and giving you the facts to work with.
But first, let me define it for you quickly: metabolism is the process by which our bodies convert the calories we consume into energy to support its functions and keep your heart beating, lungs breathing, and every cell working.
Several factors affect your metabolic rate, including your age, gender, weight, hormones, and genetics. While some of these factors are out of your control, there are still ways to maintain a healthy metabolism through diet and lifestyle habits.
Know Your Metabolism Myths & Facts
Myth: Certain Superfoods Increase Metabolism
FACT: You’ve probably seen claims about the idea that certain superfoods or supplements have the ability to fire up your metabolism. This meta-analysis did find a significant positive effect on energy expenditure after consuming caffeine, catechin, found in green tea, and capsaicin, found in hot peppers and ginger, the truth is that those impacts are small and for short periods of time (5, 6, 7).
However, one moderator of these results was BMI; those with a higher BMI at baseline corresponded to higher energy expenditure. One randomized controlled trial among overweight women found that taking green tea, capsaicin and ginger supplements each day for eight weeks had beneficial effects on weight, BMI, markers of insulin metabolism and plasma GSH levels.
So as you can see, there is some validity to these claims, but they are often overhyped. If you enjoy green tea, coffee, or hot peppers, there’s no harm in adding them to your diet (in moderation).
However, clear evidence on the benefits of caffeine pre-exercise is noted in exercise physiology. Drinking a cup of black coffee (ahem-that’s minus the milk, sugar and syrup) 30-60 minutes before exercise aids in performance, endurance and possibly a reduction in pain, supplying about 200 mg caffeine.
MYTH: Eating Smaller, More Frequent Meals
It’s a common belief that eating smaller, more frequent meals throughout the day boosts your metabolism more than the traditional breakfast, lunch, and dinner. However, there is no substantial evidence to support this myth (4).
The thermic effect of food (TEF) is the energy we expend to process, use, and store the nutrients from our meals. However, the temporary boost in our metabolic rates is directly proportional to how much and what types of foods we eat. So, while eating six small meals over the course of a day would slightly increase your metabolism six times, eating three larger meals per day can result in a similar overall effect through three proportionally larger boosts.
MYTH: Late Night Snacking Causes Fat Gain
FACT: As far as metabolism myths go, this one seems reasonable. We lie in bed while we sleep, so it stands to reason that we don’t burn many calories during that time. If we eat right before sleeping, wouldn’t that cause your body to store the meal as fat rather than burning it off, as it would be more likely to do if you were up and about.
There are two issues with this premise; first, our metabolisms do not slow down, even when we are sleeping. Our bodies are very active at night, keeping us functional and healthy through processes like breathing and maintaining our heartbeat. This study shows that metabolism actually increases during sleep in leaner individuals, while slowing down in people with obesity.
Secondly, our bodies are in a constant state of flux when it comes to using or storing energy. Our bodies are constantly switching between anabolism – building, and catabolism – breaking down. They’re pulling energy from stores when needed and refilling the stores constantly.
In short, having a late dinner or snack at night won’t automatically lead to a slowed metabolism or weight gain. However, you may be more likely to snack mindlessly in the evenings while watching television which will possibly cause a calorie surplus.
MYTH: You Have No Control Over Your Metabolic Rate
FACT: It's true that genetics help determine your metabolic rate, but so do your eating and exercise habits. New studies have shown that we have more control over our metabolism than we previously believed. Strength training, such as lifting weights, boosts your metabolism by increasing your lean muscle mass.
Muscle mass has higher metabolic activity compared to fat mass. While women certainly need both muscle and fat for good health, regularly incorporating strength training into your routine can help support a healthier metabolism. Picking up the weights also help you counteract a declining metabolic rate as you age by preserving your muscle mass.
MYTH: Lean people have faster metabolisms.
FACT: Fast metabolism is often associated with weight loss, but thin people don’t necessarily have a quicker metabolic rate. People at heavier weights actually require more energy at rest than thinner people, just by nature of having more body mass.
It takes more energy (and calorie consumption) to move a 200# frame throughout the day compared to one that weighs 125#. Indeed, a 200# woman will burn 106 calories walking a mile, while one weighing 125# burns only 67. However, the number of calories burned per day is most affected by the amount of muscle a person has.
And remember what we just said about lean muscle being more metabolically active? At the same weight, a thin person with more muscle mass will burn more calories than someone with less lean mass. As you can see, both total body weight and body composition matter.
The Bottom Line
What exactly dictates your metabolism isn’t entirely understood, but it appears that genetics, age, and modifiable factors like body composition play a role.
So instead of falling for one of the latest metabolism myths, aim to eat a nutritionally balanced diet with enough calories and protein, stay active, and work on building and maintaining muscle mass. Other practices that will positively affect metabolism include:
- Making sure you get the recommended amount of sleep each night
- Drinking more water and less sugary beverages like soft drinks and juice
- Drinking a cup of coffee – especially before workouts!
- Making sure your diet includes a healthy amount of calories, including protein; severely restricting calories can actually make it harder to lose weight, too
Try some of these simple changes, and see what a big difference they can make in your weight loss goals.
