Why Counting Calories is #FakeNews

Would you base your diet on science from a time when The Pony Express was the only way to send a letter? Or before the Stock Exchange even existed?  Probably not, but if you’re counting calories for weight loss that’s exactly what you’re doing.

The concept of the calorie was originally introduced by German scientists in the 1860s as a way to measure the efficiency of steam engines. Yep, you read that correctly. Steam engines. A calorie is simply the unit of energy needed to raise 1 kilogram of water by 1-degree Celsius. American agricultural chemist Wilbur Atwater later applied the calorie to food in order to measure energy absorbed and expended by the body.

He also came up with the idea of macronutrients – carbs, proteins, and fats – and sealed a bunch of college students in chambers to find out how much energy was in each macronutrient. He estimated, key word estimated, that carbs and proteins have approximately 4 calories per gram and fats have approximately 8.9 (rounded up to 9 for convenience…).

He took this information and published “Diet and Health,” one of the earliest diet books that utilized the calories in vs calories out approach, essentially deducing foods to numbers and allowing people to quickly compare apples to oranges to candy bars to fries without any factors other than calories taken into consideration.

The US government hopped on board with the calories in vs calories out approach due to the ease and convenience of universal comparison. In response to rising obesity rates that correlated with the low fat craze of the 90’s, the government recommended people track and count their calories as a tool for weight loss or weight management. 

Sounds simple enough, right? You track what goes in and what goes out, make sure you’re in a deficit for a long enough period of time and BAM, you hit your goal weight.

Raise your hand if this has been your experience with calorie counting.

No one? Yea, me either.  

So, what’s the problem?

If you’re relying on food labels to track your calories, think again. Food labels are off by as much as 20-25%, with an average of 8% error according to Susan Roberts, a nutritionist at Tufts University in Boston. Furthermore, food manufacturing companies are legally allowed to underestimate their calorie counts by up to 20%. Yikes.

If you think that’s enough variability to throw off your calculations, buckle up. Calories from foods are absorbed in different amounts based on many factors.

  • Calories are more readily absorbed from foods that are chopped or ground first, so the amount of calories absorbed from 10g of raw almonds is different from 10g of almond butter

  • Fruit and vegetable calorie counts vary based on their ripeness when harvested

  • Calorie counts in many complex starches decrease once a food has been heated, cooled, and reheated

  • The soil conditions in which fruits and vegetables were grown in impacts their caloric density

  • An animal’s diet and living conditions plays into the calorie count of a piece of meat

  • The length of time food was stored or transported before being processed makes a difference

  • Variations in cooking processes from batch to batch can throw of food labels  

That’s a ton of variability already, but it doesn’t stop there. Two people of roughly the same size and lifestyle habits could eat the exact same thing and both absorb different amounts of calories based on: 

  • the length of their large intestine

  • their stress level

  • sleep profile and

  • the types and amounts of bacteria in their gut 

If you know of an app that takes large intestine length into account, let me know.

What about calories out?

That being said, we’ve only covered the “calories in” portion of the “calories in vs calories out” equation. If you need more convincing that counting calories is a silly tool for weight loss, read on.

The “calories out” portion is divided into four parts:

  • Resting Metabolic Rate

    • How many calories you burn at complete rest

    • 60-75%

  • Physical activity

    • Calories burned at the gym or working out

    • 15-30%

  • Non-Exercise Activity Thermogenesis

    • Calories burned through fidgeting, standing up, brushing your teeth, etc.

    • 10-15%

  • Thermic Effects of Feeding

    • Calories burned digesting your food

    • 10%

Most people only think about the Physical Activity portion when calculating their caloric needs for weight loss and don’t realize that it only accounts for a small 15-30% of total calorie expenditure.

Additionally, fitness trackers are off, WAY off, when it comes to accuracy, according to a 2017 Stanford Medicine study. Researchers tracked the accuracy of 7 popular fitness trackers and found that the energy expenditure estimates had a margin of error of 27%. The least accurate device was off by a whopping 93%.

Now I’m admittedly not great at math, but if one number (calories in) is off by about 20%, and the other (calories out) is off by about 27%, you’re looking at calculations that could be off by almost 50%. No wonder people struggle to lose weight by counting and tracking calories!

The weight loss dogma that is CiCo (Calories In, Calories Out) is attractive because it’s simple. It gives us nice guidelines to follow with numbers, labels, and apps to take the guess work out of weight loss. However, it simply doesn’t work. We are not robots. Food is not perfectly portioned pills. We are complex organisms that cannot be boiled down to a simple equation. The CiCo method sets us up to fail and leaves us feeling guilty over a willpower problem that doesn’t actually exist, and can harm our metabolism and relationship with food in the process.  

So the next time you’re feeling lousy about not being able to count calories to reach your goal, remember: it’s not you, it’s math. Really shitty math. 

Stay tuned for next week as I dismantle the oh-so-outdated BMI.

With love,

Kate

Additional resources:

The Economist - Death of the Calorie

The Economist - Why Calories are a Con (Video)

Precision Nutrition - The Surprising Problem With Calorie Counting (Infographic)

Kate Telge