Artificial sweeteners not so sweet after all

Many people can easily give up normal soda for Diet sodas that use a sugar substitute like Sweet-n-low, or Splenda. These low calorie solutions allow you to avoid taking in half the calories you eat in your drink.

However, new research shows that using all those sugar substitutes may be for nothing. From Time:

New research suggests that the body is not so easily fooled, and that sugar substitutes are no key to weight loss — perhaps helping to explain why, despite a plethora of low-calorie food and drink, Americans are heavier than ever.

Animals fed with artificially sweetened yogurt over a two-week period consumed more calories and gained more weight — mostly in the form of fat — than animals eating yogurt flavored with glucose, a natural, high-calorie sweetener. It’s a continuation of work the Purdue group began in 2004, when they reported that animals consuming saccharin-sweetened liquids and snacks tended to eat more than animals fed high-calorie, sweetened foods. The new study, say the scientists, offers stronger evidence that how we eat may depend on automatic, conditioned responses to food that are beyond our control.

What they mean is that like Pavlov’s dog, trained to salivate at the sound of a bell, animals are similarly trained to anticipate lots of calories when they taste something sweet — in nature, sweet foods are usually loaded with calories. When an animal eats a saccharin-flavored food with no calories, however — disrupting the sweetness and calorie link — the animal tends to eat more and gain more weight, the new study shows.

Before you dismiss this as simply a psychological thing that you could easily overcome with willpower, they also found a physical link.

The sugar-fed rats, for example, showed the expected uptick in core body temperature at mealtime, corresponding to their anticipation of a bolus of calories that they would need to start burning off — a sort of metabolic revving of the energy engines. The saccharin-fed animals, on the other hand, showed no such rise in temperature. The net result is a more sluggish metabolism that stores, rather than burns, incoming excess calories.

Also, there is evidence that this link will be found in humans.

A University of Texas Health Science Center survey in 2005 found that people who drink diet soft drinks may actually gain weight; in that study, for every can of diet soda people consumed each day, there was a 41% increased risk of being overweight.