science of us

# Are Calories Pointless?

Photo: BSIP/UIG via Getty Images

Counting calories is very ’90s. Eighteen-nineties, that is. But also 1990s, and the whole time in between, and maybe up until right now. What if it’s all been basically pointless? If I hadn’t been counting calories, might I get back weeks — months — of my life?

In the latest issue of The Economist’s 1843 Magazine, writer Peter Wilson outlines the rise and, now, fall — and possibly “death” — of the concept of the calorie. There is mounting evidence that the idea of “calories in and calories out” is so “dangerously flawed,” Wilson writes, that it’s time to rethink the whole thing. One-hundred calories in a banana, 190 calories in two tablespoons of peanut butter: Are these not facts I needed to memorize? Are they not even facts?

Mathematically, a calorie is the amount of energy required to heat up one gram of water one degree Celsius (or 1.8 degrees Fahrenheit). Using calories to measure the fueling capacity of food dates to the 1860s, and using calories to measure food’s capacity to heat/fuel the human body in particular dates to 1887, when an American agricultural chemist determined via some dramatic experiments on college students (who were each sealed voluntarily into an underground tomblike chamber to eat, sleep, lift weights, and be monitored) that a gram of protein contains four calories, a gram of carbohydrate four calories, and a gram of fat nine-ish calories. These numbers have remained the standard since.

One of the problems with this, Wilson writes, is that “each body processes calories differently.” It’s why my friend and I could both eat the same thing and have entirely different digestive reactions. Some factors that go into this are the amount of sleep we’ve gotten, the time of day we eat, our particular microbiomes (the bacteria in our individual guts), and the sizes of our intestines. “The more we probe,” Wilson writes, “the more we realize that tallying calories will do little to help us control our weight or even maintain a healthy diet.” (I knew it, I and probably most people thought while reading Wilson’s story.)

It was especially interesting/disconcerting to learn, for instance, that the calories in certain freshly cooked foods (like pasta and bread) are more readily absorbed than the calories in the exact same food that’s been left to cool and then reheated. “As starch molecules cool,” Wilson writes, “they form new structures that are harder to digest.” This would all be funnier if so many people hadn’t based their whole lives around calorie-counting.

Wilson asks why the concept of the calorie persists if it’s so outmoded. It could be, as one of his interviewees proposes, because the idea of a fixed, quantifiable calorie is good for business, since it basically lets the makers of sugary and processed foods “off the hook.” If a calorie is a calorie, then it doesn’t matter where you get them. (I would like to imagine that I inspired Wilson to do this work with my influential 28-word 2011 story “Wine Calories.”)

Wilson doesn’t explicitly suggest an alternate course of action, but threaded through his article is the story of a man who at first counted calories religiously but only lost weight when he abandoned that to instead eat whole foods more intuitively.

I appreciated the playful but serious detail at the end of the story, in Wilson’s bio, in which he reveals that he lost almost 29 pounds during the course of researching the story.

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Are Calories Pointless?