Diet soda health risks may be greater than previously thought. Diet soda may ruin metabolisms-and even increase weight gain.

A growing body of evidence suggests that diet soda health risks outweigh the benefits. Researchers are learning that diet soda may be associated with weight gain and other harmful problems.

Weight gain, as awful as it may sound, is just the tip of the diet soda health risk iceberg.  Susan Swithers wrote in a new opinion piece published in the journal Trends in Endocrinology and Metabolism, "accumulating evidence suggests that frequent consumers of these sugar substitutes (such as aspartame, sucralose, and saccharin) may also be at increased risk of ... metabolic syndrome, type 2 diabetes and cardiovascular disease."

Swithers also says, "Frequent consumption of high-intensity [artificial] sweeteners may have the counterintuitive effect of inducing metabolic derangements."

By "metabolic derangements", Switehrs means that diet soda may make the body confused in response to real sugar because it can't process the fake sugar.

Hormones that say "sweet stuff coming, get ready to digest!" to the gut when diet soda hits the mouth go haywire. After a while, "we may no longer release the hormones" needed to process sugar, said Swithers; the body can't predict what's coming and whether it's real.

The San Antonio Heart Study found plausible correlation between diet soda consumption and weight gain over time years ago.

"On average, for each diet soft drink our participants drank per day, they were 65 percent more likely to become overweight during the next seven to eight years" said Sharon Fowler to press.

"The take-home message is for people to be much mindful of how much sweetener, whether artificial or sugar, they're actually consuming," said Swithers.

Some studies suggested diet and non-diet soda may be equally harmful. And people who order diet soda may justify overindulging with food because of the diet soda.

"Are diet sodas worse for you than regular sodas? I think that's the wrong question," said Swithers. "It's, 'What good are sodas for you in the first place?' "