I THOUGHT I KNEW WHAT A CALORIE WAS.
A calorie is not a calorie, as least, not the way we’ve come to know it. When I think back to health class in high school, I learned that a gram of protein, carbohydrate and fat have 4, 4, and 9 ‘calories’, respectively. These numbers represent the average energy absorbed by my body when I digest one gram of each type of food.
From my many physics classes, I learned that one calorie is the amount of energy required to raise the temperature of on gram of water by one degree Celsius (and what we commonly refer to as a ‘calorie’ is actually a kilocalorie, or a thousand calories.)
So when it comes to taking care of myself, all I have to do to lose (or maintain) weight is to workout and diligently count calories and then I’ll be great, right?
Well, sort of. It’s true that what you put into your body plus what you burn is the ultimate equation for you to balance. In college, I lost a decent amount of weight by using my love of Excel and diving into the USDA nutrition database to record everything I ate, weighed or portioned out to measure exact calories when possible. I wanted to make sure I wasn’t eating too much—or too little. (Fortunately, now there are plenty of fitness tracking apps, such as MyFitnessPal.)
But what happens when what you think you’re putting in your body turns out to not be totally accurate?
THEN WHAT IS A CALORIE?
New studies, and some not-so-new studies, have shed a bit more light onto what we think we’re consuming. The short of it is that the average calorie counts of 4 and 9 were developed by chemist Wilbur Olin Atwater in the 19th century. There is one key factor to notice here: average.
Any two foods may be digested in various ways, even if they look the same. In fact, just because a food has the same grams of fat, protein and carbohydrates, it may actually be harder to digest resulting in a lower net calorie count than a seemingly comparable food. (E.g., in a study by the USDA, they found that almonds actually result in 129 net calories as opposed to the 170 reported on the label.) Aside from natural composition, how the food is treated and processed will affect the net calorie count.
Here are just a few factors that affect the net calorie count of food:
- Digestion efficiency (evolved by food or your genetic ancestors)
- Traditional cooking method (boiling, baking)
- Modern cooking method (microwave)
- Preservatives or other food treatments
- Level of digestion-assisting bacteria in your stomach
DOES THIS MEAN I AM SCREWED?
No. My take** on this is that I will do three things to better understand how to optimize my calories eaten + calories burned equation:
(1) USE TRADITIONAL CALORIES AS A BALLPARK
Although the traditional calorie counts aren’t necessarily accurate, I can still use them to roughly estimate what you’re eating – and helps me have a better way to compare the potential “goodness” of various types of foods.
(2) EAT MORE WHOLE AND RAW FOODS
Clearly, cooking breaks food down to make it more easily digestible. Similarly, the more processed a food, the less energy that needs to be expended by my body in digestion, potentially resulting in higher actual net calorie count than expected.
(3) LISTEN TO MY BODY
Because each person may digest food differently, it’s important to be constantly learning and improving my relationship with food. What works best for my body? How do certain foods make me feel? What kind of energy do they give me?
Ultimately, it’s about feeling as healthy and happy as possible—and that means being true to my “eating self.”
FURTHER RECOMMENDED READING
If you’d like to read more, below are some studies and articles I suggest you explore.
Postprandial Energy Expenditure in Whole-Food and Processed-Food Meals: Implications for Daily Energy Expenditure. Sadie B. Barr and Jonathan C. Wright in Food & Nutrition Research, Vol. 54; 2010.
Discrepancy between the Atwater Factor Predicted and Empirically Measured Energy Values of Almonds in Human Diets. Janet A. Novotny, Sarah K. Gebauer and David J. Baer in American Journal of Clinical Nutrition, Vol. 96, No. 2, pages 296-301; August 1, 2012.
The Hidden Truth About Calories, Scientific American, August 2012.