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Calorie Density: Too Good to Resist
Almost everybody loves high-calorie foods, but does this mean we’re instinctively attracted to foods that are jam-packed with calories? You bet it does. Calories are king all over the world, in every culture. In the west, we love brownies, doughnuts, chips, cheese and hot fudge sundaes. In China, the most popular foods are braised pork bellies, meat-filled dumplings, fried dough and fried scallion pancakesthe highest-calorie foods available. Even in Africa, where calorie-rich foods are generally hard to find, people seek out the most calorie-laden things they can get their hands on, such as white bread made from imported flour, and add oil to any recipe when it can be afforded.
An affinity for foods loaded with calories was an asset during early human development, when the next meal was an unpredictable event. It made sense back then to eat calorie-rich foods because they provided the most energy. Today, however, our instinctive attraction to those foods stands directly in the way of controlling our weight.
The other thing to realize is that we’ve been blindsided. People have always loved calories, but opportunities to enjoy them have increased dramatically. Forty years ago, few people ate outside of mealtimes and regular snack times. And with the exception of an occasional ice-cream cone, almost no one ate while walking down the street. Nowadays, it’s hard to make a quick trip to the mall without encountering the enticing odor of a Cinnabon (730 calories a roll). We can’t undo the world we live in, but we can learn to use the best strategies that science can offer to help us avoid giving in to our perfectly natural love of calories.
That Food-Is-Bliss Feeling
Contrary to what you might think, there is no magic in the actual taste of the high-calorie foods we love. As shown by Adam Drewnowski of the University of Washington, the story is simple. The more calories per ounce a food has, the more we prefer it. The more we prefer it, the more tempting it looks on our plate.
We love high-calorie foods because when we eat them the reward center in our food brain releases feel-good chemicals like dopamine. Our brain is remarkably good at learning to anticipate what tastes come with what calories. We quickly learn that, say, brownies release pleasing chemicals in our brain, so we learn to like the way they taste and when we see that food again we want to gobble it up.
Interestingly, it doesn’t seem to matter whether our calories come from fat, carbohydrates or protein. In fact, the most popular foods are actually a mixture of all three of these. Most of us are not simply “carboholics” but “calorieholics,” and our strongest preferences are for foods containing some of those rapidly digested white carbs, with a little fat and protein thrown in for good measure.
The Power of Leptin
Here’s something you may be confused about now. If we instinctively love calories, how can we ever truly hope to enjoy food that helps weigh loss? Won’t a brownie always taste better?
The answer to this riddle is emerging from new research studies, and leptin is a key player. Leptin is a hormone secreted from fat cells to help control various processes, like whether you feel hungry or full. When you’re overweight and overeating, leptin is secreted in excessive amounts. The more you eat, the more leptin in your bloodstream, and one of the things it does is suppress neuronal firing in both the cortex and midbrain areas where your taste and reward sensations occur. This means that when you’ve gained weight, you can’t enjoy food a much because leptin is damping down your pleasure centers and pretty soon only really indulgent foods taste good. But as you lose weight, your leptin levels drop, your neurons are released from their leptin prison and healthy food starts to taste good. This explains something we’ve noticed at Tufts, which is that during and after weight loss our volunteers become more sensitive to food pleasure and lower-calorie foods taste better and better. Sure, calorie-rich foods will always taste good if you keep eating them, but when lower-calorie foods start tasting as good as those high-calories goodies once didwhy bother?