Sugars have long been believed to bring about an amphetamine-style chemical change in the human brain. The exact nature of the supposed "sugar high" has been disputed, but there's little doubt that it can become a problem bordering on addiction and that environmental conditioning requires one to consume more and more sugar to reach the same levels of sucrose satisfaction. New research shows that rich, calorie-heavy foods invoke a very similar response. These findings imply that the brain can accurately gague caloric content and that the positive response to and subsequent desire for these foods supersedes the appeal of taste.
In the most recent study surrounding this topic, Duke University researchers focused on the preferences of a group of lab mice engineered to lack sweet-taste receptors. These altered mice were still found, on the whole, to prefer real sugar to artificial, non-caloric sweeteners, and their preferences stemmed from the only substantive difference between the two substances: caloric content. While the diet-conscious primarily think of high calorie foods as treats we should avoid, the body seems to have an underlying ability to gague the amount of calories in a particular form of food when it's consumed. Animals will return to these high-calorie foods without fail. Why? They're are simply more filling, and lab rats and wild mammals aren't terribly concerned with retaining their youthful figures.
Given an initial choice between sucrose-based sugar water and pure H20, the engineered mice did not show a preference for either. Both they and the control group were then deprived of sustenance for a period until they were both hungry and thirsty. Because sucrose-water contained more calories, both sets of mice initially preferred it, and they continued to draw more from the sucrose sipper after both containers were refilled with plain water, hinting at their sensitivity to the substance. However, when the entire experiment was run again and an artificial sweetener was substituted for the sucrose, the patterns changed: control mice still preferred the sweet water, but engineered mice showed no preference. These tasteless mice couldn't distinguish any nutritional difference between the two liquids because there is none. The researchers' conclusion: both groups of mice were drawn to the sucrose water because it provided more calorie-based sustenance. Drinking sugar water would satisfy both the thirst and the hunger of these mice more fully than water alone, sweetened or not. And they were able to determine this fact without considering the taste factor. Researchers also noted differences in the sugar-dopamine release pattern indicating that this reaction is not only prompted by taste. Control mice displayed elevated dopamine levels when drinking the artificially sweetened water, but engineered mice only saw the same dopamine infusions when consuming the sucrose. The calories themselves, then, provoked a desirable internal response.
"Comfort" food, it would seem, is just that. Not only does it facilitate increased dopamine production and have a momentary effect on mood, it also reassures us through familiarity. We know exactly what it will look and taste like, and that degree of comfort may lead us to eat more of it even when its health effects are particularly undesirable. But the initial tendency to prefer these foods quite possibly stems again from the evolutionary survival instinct, as animals learned to seek out richer foods that would last longer in a hunter-gatherer schema. It also illustrates another reason why our biological impulses have yet to catch up with the reality of present-day society, and how these very basic instincts facilitate unhealthy behavior. We're driven to eat as if it's a matter of life or death, and we're growing consistently overweight because of it.
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