Artificial sweeteners were developed incidentally but are now commonly used in food and beverage production. Saccharin, discovered at John Hopkins during research with coal tar derivatives, was originally marketed as a product for diabetics. Sugar shortages and the popularization of a thin physique led to advertisement of saccharin and new artificial sweeteners as diet aids. It was assumed that consuming artificial sweeteners in place of sugar would cut calorie consumption and lead to weight loss. Counterintuitively, studies have found positive correlation between intake of artificial sweeteners, weight gain, and increased BMI.
This correlation may result from differential processing of sugar intake versus artificial sweetener intake in the brain. With intake of sugars such as sucrose or glucose, the perceived pleasantness of sugars decreases, subsequent caloric intake decreases, and food reward pathways involved in satiety are activated. Intake of artificial sweeteners, like aspartame, acesulfame potassium, and saccharin, do not produce these effects. Notably, differences in artificial sweeteners’ activation of food reward pathways may lead the body to increase, rather than limit, overall caloric intake.
Natural and artificial sweeteners are perceived as tasting roughly the same because they activate the same taste receptors their subsequent pathways through the thalamus to the insula/operculum and orbitofrontal cortex. While the sensory perception is similar, however, postingestive processing differs. The hypothalamus works to regulate this process, secreting neuropeptides that affect energy, osmotic balance, and feeding behaviors. Ingestion of natural sweeteners leads to signal depression in the hypothalamus, along with greater activation of the insula, orbitofrontal cortex, and amygdala. Artificial sweeteners, in that they lack the caloric component inherent in natural sweeteners, only partially activate these pathways. Consequently, they result in a lack of satiety and fail to quell animals’ inherent craving for sweetness.
In addition to increasing appetite and cravings for sweetness in the short term, artificial sweeteners ingested over time elicit sugar dependence. Habitual use leads to a shift in flavor preferences. Systematic reduction of artificial sweetener use can reshape these preferences. “Unsweetening the world’s diet,” ie altering flavor preferences to less sweet foods, will be key in overcoming the current obesity epidemic.