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Why Artificial Sweeteners Can Cause Overeating


Although we may believe food and drink made with artificial sweeteners help us lose weight, research suggests the opposite is true.

The reason diet foods can trigger overeating and weight gain has to with a hormone called leptin. Leptin is an appetite regulating hormone that signals our brain when we have taken in enough calories and are “full.”

Artificial sweeteners such as aspartame and saccharin can fool our taste buds into registering sweetness, but they do not signal our brain to dish-out hunger suppressing leptin.

Natural vs. Artificial Sugars

When we consume something sweetened naturally (e.g., table sugar, honey) our brain releases the neurotransmitter dopamine. This stimulates a sense of pleasure, and our appetite, because dopamine activates our brain’s reward center.

Naturally sweetened food also signals the brain to release a supply of leptin. The leptin eventually lets us know we should be sensible and stop eating, though the food may taste heavenly.

Eating foods containing a non-caloric artificial sweetener, our reward center is also stimulated by dopamine. We experience pleasure, and an increased appetite, but nothing signals our leptin to step up its production and start circulating.

Without available leptin we do not get an “I’m full” signal from our body to put the brakes on our eating pleasure, and people tend to overeat.

A Note About Fructose and Weight Gain

Many food products and drinks today are sweetened with the sugar fructose, often as high fructose corn syrup. Because of this, many of us are consuming more fructose than is good for us. Eating too much glucose can be harmful too, but glucose affects our body differently than fructose.

The sugar glucose stimulates the action of leptin and has a dampening effect on the hormone ghrelin that tells us when we are hungry. However, fructose interferes with the release of leptin and does not suppress the appetite hormone ghrelin. So, people ingesting a lot of fructose-laden food and drink are more likely to overeat.

Photo credit: Steve Snodgrass