What is a Calorie, and Should I Count Them?

what is a calorie

Jessica Halper MPH, RNutr, always has health on her mind. Today, she’s making a case for looking beyond calorie count when planning a meal.

“Rose is a rose is a rose,” the American novelist Gertrude Stein once said. Although the sentence was first written in 1913, this truism carries through to today. Things are what they are. “A is A” and “B is B” and, as such, everything appears as it is. 

In the world of dietary health, many have applied this logic to calorie counting—a practice of managing one’s weight by tracking “calories in” and “calories out.” If each thing is identical with itself, then a calorie is a calorie. Thus, whether enjoying 100 calories of steamed veggies or 100 calories of potato chips, all is equal and all is right. As long as you stay within your daily allotted calories, you can eat anything you want right?  What a world that would be. Sadly, it’s more complicated than that.

By its simplest definition, a calorie is a unit of energy equivalent to 4.184 absolute Joules. In popular press and food labeling practices, a food calorie actually refers to a kilocalorie, or 1000 cal. That is, 1 food cal equals 1 kcal, or the amount of energy needed to raise 1 kg water from 15 to 16°C.

The first law of thermodynamics states energy can neither be created nor destroyed, only transformed. By this law, consuming foods identical in caloric content should produce identical amounts of energy, and result in identical weight changes, independent of the foods’ nutritional profile. This line of thinking informed methods of calorie counting in which the type of calories consumed (steamed veggies vs. potato chips) is ignored. 

While the notion that we can subsist, or even lose weight, on a diet of sweet and salty treats is appealing, it’s not true. The human body is not a perfect engine. It’s a multifaceted and messy machine equipped with varying biochemical processes. Different foods are metabolized through different pathways, some of which are more efficient than others. For example, the body is much more skilled at processing carbohydrates than protein. This suggests that the body is able to extract more energy from carbohydrates. 

Confused? You’re not alone. The field of nutrition is notoriously confusing and constantly evolving. Even though foods should not be evaluated purely by their caloric content, there are benefits to tracking your intake and remaining mindful of the calories you consume versus those you expend. If you’re looking to lose weight, your diet will likely rely on a calorie deficit in regards to a baseline, which can be caluclated based on your size and sex. 

Whatever your health goals are, it’s always important to assess the quality, not just the quantity of your caloric intake. Even if you’re seeking to reduce calories, always choose a balanced diet to ensure your body is meeting its nutritional needs. Steer clear of packaged foods, and be wary of unsubstantiated health claims. Remember, just because something is low in calories, doesn’t mean it’s healthy. Instead, opt for fresh, minimally processed foods such as fresh produce and whole grains. View your diet as a whole, rather than the sum of its parts.

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