Fat, carb, protein - does it really matter what form a calorie

comes in? 

According to the tidy

little illusion of calorie math, no. We treat calories like currency – all

totals being equal whether counted in coins, bills, or silver bars.

Yet, is a

calorie really a calorie, no matter the form or source?

Under all conditions to all individuals

at all times?

It’s tempting to think

this way. Yet, science begs to differ. 

Technically speaking,

a calorie is a measure of how much energy something releases when it’s

combusted in a closed system (called a bomb calorimeter in laboratory

settings). 

One calorie is the

amount of energy required to raise the temperature of one gram of water by one

degree Celsius.

The calories reported

on food labels are actually kilocalories, often written with a capitalized “C.”

(That’s why you’ll see me capitalize references to Calories for the rest of our

discussion (or list them as kcal).

But the real question is this: is a Calorie really a Calorie, no matter what? Let’s break it down.

Article ShortcutsQuestionable Calorie CountsThermic Effect and SatietyWe are what we eat, digest, and absorb.Should you ignore

calories?

Questionable Calorie Counts

I hate to break it to

you, but the calorie counts we see on food packages are flawed. Maybe this explains

why some struggle to manage their weight despite meticulous “calorie counting”?

The USDA maintains one of the most extensive, free food databases in the world. The calorie numbers measured in lab settings - which are tightly-controlled, closed systems where energy cannot be "lost" - don't always behave predictably when applied in real-world settings.

Our bodies are open biological systems, so the exact calorie dynamics observed in lab settings don’t carry over perfectly.

The scientists who

perform the lab analyses to determine the Calorie content of foods recommend

the public treat these numbers as estimates at best.

Go figure. 

To report calories on

a food label, a food manufacturer can either perform its own bomb calorimeter

testing (costly and time-consuming) or use existing ingredient data from the

USDA database to extrapolate the data to their product (quick and dirty

method). To control costs and maximize profits, which method would you follow?

When reporting final Calorie counts for labels, these values are required to be accurate within 20% of actual measures, but in all reality no one really checks this before a product reaches our shelves. 

Calorie accuracy is all over the map when researchers compare actual calories against labeled amounts on commercially prepared foods.

A more truthful name

for 100-calorie packs could be “somewhere around 80- to 120-Calorie

packs – we think.”

To muddy the waters a bit more, many free calorie-counter apps source their data from the huge USDA database and allow their millions of users to also create custom foods for all other users to select from. This explains why there may be upwards of 30 choices for chicken breast when you go to log your food. Your Calorie counts are only as accurate as Joe-user’s interpretation or best guess.

Sadly, even if you have the best intentions by trying to track your Calories accurately, your 1500-Calorie plan could really be supplying anywhere from 1200 to 1800 Calories!