Do You Have a Fast Metabolism?

No. You don’t. Nobody has a “fast” or “slow” metabolism.

I know I know, jerk move. But let me explain.

What is Metabolism?

Metabolism refers to the chemical reactions your cells carry out to regulate energy use. That can be burning energy (the conventional idea of metabolism) or storing it (its lesser known other half). The reality is, these reactions are lightning fast no matter how you spin the wheel, and they don't vary measurably between individuals.

People with “fast” metabolisms have numerous factors contributing to their apparent lack of fat gain – none of which relate to "metabolism speed". Let's get into it.

Fat Distribution

People might be shaped differently because of the way their bodies store fat. For example, some ladies have more fat stored in their breasts than others. Some people’s bodies want to store more fat in the thighs. Others want to store more in the abdomen.

These differences in fat distribution can make some people appear bigger than others. Somebody whose body stores fat in their breasts before their belly or hips will "look less fat" than another whose fat is more evenly distributed.

Basal Metabolic Rate

I know this has “metabolic” in it, but it’s not about how fast your cells go. Well actually, it is. But not in the way you think.

Basal metabolic rate (BMR) is a (generally) fixed number indicating how much energy your body needs to maintain itself per day, disregarding any physical activity. In other words, how many calories would you need if you were sleeping all day?

This depends on someone’s height, mass, and muscle mass (which can correlate with sex at birth). Generally taller, larger, male people (or people with lots of testosterone floating around) require more calories per day to exist. Taller/larger people have more numerous and perhaps larger cells. This requires more energy to maintain all of them.

As for the male/female difference, I attribute this to muscle:fat cell ratio. Men tend to have more muscle cells compared to fat cells than women, and muscle cells burn more energy (calories) than fat cells*.

Adorable. Guess who has the higher BMR?

Activity Level

When you're moving your muscles, you're burning calories.

People who move with high intensity for a long time and do it frequently will have higher energy needs than people who move with low intensity for short periods of time infrequently:

• Someone who runs will burn more than someone who walks.

• Someone who runs for 30 minutes will burn more than someone who runs for 10 minutes.

• Someone who runs 3x a week will burn more than someone who runs once a week.

The person who runs for 30 minutes 3x a week will burn much more than the person who walks for 10 minutes once a week.

(That said, walking, running, and other forms of cardio are not my recommended ways to shed fat and keep it off. Check out my article Exercise: a Broad Term.)

Your calorie needs for a given day can be calculated using: BMRx1.2** + calories burned from physical activity. Therefore, if you're regularly moving your muscles for a long time with high intensity, your calorie needs will be much higher than just your BMR.

Food and Lifestyle Habits

Have you ever studied the habits of one of those people who seem to be able to eat whatever they want, yet NEVER gain weight?

I have.

People who never gain weight usually do one or more of these things, consistently:

• Eat little for their size, muscle mass and activity level

• Eat low-calorie foods

• Fast for long periods of time

• Live a life that burns lots of calories (see Activity Level above)

Because of this, that one night when they've eaten the entire bowl of Cheetos and drank enough sangria to put your Aunt Marge to shame, it has little impact on their overall weight.

Put down the sangria, Aunt Marge.

It’s their consistency that counts. Most of the time, they're engaging in behaviours that keep their calorie intake about the same as (or lower than) their calorie output.

This is what it comes down to, folks.

You are not doomed by genetics.

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*From this, we can infer that increasing your muscle:fat cell ratio (ie. by weight training) can increase your basal metabolic rate regardless of height, mass, or sex.

**The multiplication by 1.2 accounts for the fact that you are not, in fact, sleeping during the day, and are walking around a bit, fidgeting, etc.