The Metabolism Myth: Separating Fact from Fiction

Debunk: This myth is actually true to a certain degree. But, like most things, it is much more complicated beneath the surface. A good example is green tea. Studies show that this caffeinated beverage can increase energy expenditure by 4.7-4.8%. The rate at which your body burns food is not sped up, but the amount of energy you’re burning is increasing. This value can be measured as NEAT, Non-Exercise Activity Thermogenesis, seen as fidgeting, leg shaking, typing, walking up the stairs, etc. These, amongst millions more, are small things that require energy and thus burn more “calories” (but really, ATP: see myth 8). So, next time you have a caffeinated tea and notice that you’re more fidgety when sitting down, this could be an effect of that “metabolism booster” quality.

Debunk: If you are eating in a caloric deficit, your metabolism will slow down very quickly in response. Back in human hunter days, food was way less available - they didn’t exactly have grocery stores around the corner. If there was a tougher week with less food in their area, metabolisms would slow to keep them alive. Without this adaptation, one’s body would still require the same amount of energy, burn through all the stored adipose tissue and then muscle, until they die. Though this is a more extreme instance, it is the same as skipping meals. Not eating lunch here and there will not hurt you, but routinely skipping dinner will push that “panic” button in your brain and stimulate metabolism-slowing procedures. If you wish to speed up your metabolism to lose weight, focus on building muscle (see: myth 6) and eating well and balanced.

Debunk: With less body mass to operate, a leaner person’s metabolism is slower. Yes, if they have a lot of muscle mass (see: myth 6) their metabolism may be significantly faster, but speaking of generally “skinny” people, this is the opposite. Odds are, they get fuller faster and stay active, therefore maintaining their weight easier. The amount of energy required to pump their blood, help them walk across the street, and digest the – smaller quantities of – food they eat is less than that of a higher-BMI individual. A good way to think about this is the car analogy again. A small sedan going 60 mph takes less energy than a large SUV going 60 mph because it has less mass to move. As a result, the sedan’s gas tank is smaller and mileage is higher - it can go further on the same amount of gasoline. In that manner, a thinner person may eat less food and metabolize it slower, being able to walk more distance on the same chicken sandwich they ate at lunch.

Debunk: A calorie is the amount of energy it takes to raise 1g H2O by 1 degree Celsius, not the amount of energy in a blueberry. The FDA uses calories to measure how much energy content is in a certain quantity of a certain food. But your body doesn’t know what a calorie is, rather it knows that a slice of bread will give it 15 grams of glucose molecules that can be used to help your brain remember what was taught in math class on Tuesday. The process utilized to break down these foods into glucose for your cells is called Cellular Respiration, in which one glucose molecule is turned into ATP, adenosine triphosphate, which stores potential chemical energy within its bonds. (You can read more about what happens at the cellular level here.) This potential energy is released when the intramolecular bonds are broken and that is how your body metabolizes food into energy.