Americans drink lots of diet soda and Americans are facing an unprecedented obesity epidemic. This has caused all sorts of medical experts and even Oprah to investigate whether diet soft drinks can make you gain weight.

It seems paradoxical that a product with no calories could result in gaining weight. In fact, most of us don’t believe this to be the case. But the untold secret of diet beverages is this: weight gain is complicated. It’s not strictly a matter of what you ingest, it’s what your body thinks you ingested.

Artificial sweeteners, particularly aspartame, can trick the body into thinking that sugar is being ingested, which causes the body to release extra insulin to help metabolize that sugar. That would be appropriate if you actually were eating sugar. This insulin spike causes the body to remove glucose from the blood stream and store it away as fat. Meanwhile, the body now realizes that there are no calories coming, but it’s too late because the insulin has already hit your blood stream. This sets the stage for low blood sugar, which, in turn, triggers your urge to grab something super-sweet.

If this happened once in a while, your body could manage. But if this is a daily or several-times-a-day occurrence, your blood sugar and appetite can get severely out of whack while your pancreas exhausts itself trying to produce the large amounts of insulin it thinks you need.

The University of Texas Health Science Center in San Antonio researches obesity issues and they also are investigating that artificial sweeteners may increase your risk of obesity in that these sweeteners play head games with you. That is, something in their chemical structure that may alter the way the brain processes serotonin, a powerful neurotransmitter that helps tell us when we’re full. If you eat natural foods, serotonin steps in and turns off your appetite at the brain level. But if an artificial sweetener has messed up serotonin levels, your appetite stays on long after it should have switched off.

While researchers cannot prove conclusively how diet sodas make you gain weight, it is clear that a nation of diet-soda lovers is getting fatter and fatter.

So what can you do?

• Stop drinking diet sodas—actually switch over to water. And don’t use artificially sweetened flavors in your water. If you need something to flavor your water try natural lemon or lime juice
• Eliminate artificial sweeteners as much as possible from the rest of your diet
• Try to increase the natural foods you eat; you don’t need to go to a health spa! Just pick up fruits and veggies at the grocery store
• Build a sensible diet and exercise program that does not revolve around sugar-free diet products