The Science Of Small: Why Your Height Is Affecting Your Weight Loss

Have you ever suspected that your height may be hindering your fitness goals?

While losing weight is hard for everybody, it’s especially difficult for petites.

We have what I call the Tiny Trifecta, which are three scientific factors that underscore our need for a different approach to fitness. Together, these three little principles add up to have a huge and sneaky impact on our weight over time.

PRINCIPLE 1: Eating in a caloric deficit is hard—even for tall people.

Albeit an oversimplification, the following equation has been used for decades to illustrate the body's use of calories.

Calories in (through food and drinks, including alcohol) – Calories out (through exercise and your metabolism) = Your weight

Of course, if losing weight were as simple as the equation above, we'd all have the same slender figure walking down the street.

In reality, many biological factors play a role in weight loss, from genetics, to physical activity, sleep, stress and hormones. 

This equation remains important for the sake of this article to help illustrate some simple math problems.

In many weight loss and fitness programs, people are told that they need to manipulate this equation so that the calories in is less than the calories out, which is called being in a caloric deficit. Most people can achieve this using a combination of diet and exercise, but either way, it requires a conscious effort and the willingness to change one’s lifestyle.

For most, this is the largest obstacle they will face when trying to get into shape, and it’s no small challenge by any means. But for petites, this is just the beginning. We have so much more to overcome from a scientific standpoint.

PRINCIPLE 2: We petites have a minuscule calorie maintenance.

Everyone has a specific number of calories they can eat in a day to maintain their current weight. This is called maintenance calories, and for petites, it tends to be much lower than that of our taller friends. It’s simple math.

Let’s calculate the maintenance calories, or Basal Metabolic Rate (BMR), of my friend Skyler, a 5’1” petite who works a 45-hour workweek and rarely has time to work out.

We’ll use a formula called the Harris Benedict Equation for estimating BMR:

BMR = 650 + (4.35 x Skyler’s weight in pounds: 140) + (4.7 x Skyler’s height in inches: 61) – (4.7 x Skyler’s age in years: 25)

= 1428.2 calories. This is how many calories it would take Skyler to maintain her weight if she did not exercise.

Stick with me for a moment. Now let’s factor in Skyler’s activity level to see how many calories it actually takes to keep her body up and running. Since she exercises maybe once a week, her lifestyle or activity multiplier would be 1.2 (refer to the appendix for the full list of multipliers), which I’ll now multiply by her BMR:

1428.2 (her BMR) x 1.2 (her lifestyle multiplier)

= 1713.8 daily calories to maintain her current weight.

If Skyler wants to lose weight, she would need to eat less than 1713.8 calories a day, which could easily translate into two measly meals, or three small, 450 calorie meals a day, with no snacking.

Ugh! It’s just not fair.

PRINCIPLE 3: We have less room for error.

It's about to get even worse for us. Get ready for the third scientific obstacle in the Tiny Trifecta that we have to worry about that our tall friends don’t.

Skyler’s boyfriend Ben is a chap with a 2,500-calorie maintenance. He decides to go on a diet of 2,000 calories per day. This means that over the course of a week, Ben eats a total of 3,500 calories less than usual, and after one week, he loses one pound (1 pound = 3,500 calories).

On week two, Ben “messes up” one night. He goes out to dinner and then drinking with the bros and ends up eating 3,500 calories in one day. So how does this affect his goal of losing one pound per week?

The other six days of the week, he had met his goal of eating in a 500-calorie deficit, for a total of 3,000 calories still under maintenance. On the night he overate, he ate 1,000 calories over his maintenance.

So, 3,000 – 1,000 = 2,000 calories still under maintenance by the end of the week, even though he completely “messed up” that one night.

And the result? Ben still loses over half a pound!

Compare this to Skyler when she “messes up” one night:

Recall that Skyler’s calorie maintenance is 1,700, rounded down. Skyler goes on the same calorie deficit as Ben, knocking 500 calories off of her maintenance for a daily goal of 1,200 calories per day.

Skyler also “messes up” and eats the same 3,500 calories that night as Ben, putting her over her maintenance by 1,800 calories. She still ate a 500-calorie deficit the other six days, coming out to 3,000 calories still under maintenance.

3,000 – 1,800 = 1,200 calories still under maintenance. What happens to Skyler this week?

Skyler loses .3 pounds! A negligible amount. Skyler’s whole week gets thrown off by one night, whereas Ben’s result hardly counts as a set-back.

The Bottom Line

Unfortunately, the math matters more for us.

As petites, we have fewer calories we can play with in a day, which makes our margin for error much smaller, and our caloric balance more likely to tip into a surplus, which contributes to weight gain.

While we are not all made the same, and there is much more to weight loss than a simple equation, it certainly doesn't help us that one aspect of the math rules out of our favor. 

The culmination of these three scientific hurdles is what I call the Science of Small, and it just means that we petites need to get smarter about how we approach our bodies.

To take the next step and learn how to harness the Science of Small to get your best body, check out my fitness and nutrition E-books.


The Harris Benedict Equation

To determine your total daily calorie needs, multiply your BMR by the appropriate lifestyle multiplier, as follows:

  • Sedentary (little or no exercise): BMR x 1.2

  • Lightly active (light exercises/sports 1-3 days/week): BMR x 1.375

  • Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55

  • Very active (hard exercise/sports 6-7 days/week): BMR x 1.725

  • Extra active (very hard exercise/sports & physical job or 2x daily training): BMR x 1.9