There are increasing numbers of studies that suggest our bodies may learn to associate certain tastes with higher or lower calorie levels.¹ When we eat something that tastes like it should be higher in calories, such as a diet soda, our bodies expect to get those calories. And when our bodies don't get those expected calories associated with the sweet taste they go on the search to find them. The body could have a metabolic response simply by craving those missing calories and could therefore produce weight-gaining hormones whether those calories are attached to the sweet taste or not so it's a good idea not to trick your body with diet foods that do little more than add to your weight problems.² This isn't to say that diet foods necessarily cause weight gain, however, there is increasing evidence that no-calorie sweeteners may be just as guilty as sugar in our weight control struggle.

A zero-calorie drink or snack could produce a metabolic response simply because it tastes sweet. It can condition you to develop a preference for sweet things, which can lead to weight gain or metabolic syndrome. So something that is sweet could produce a metabolic effect even if it doesn't have a lot of calories. Numerous blood glucose tests have shown that the body senses the sweet taste of artificial sweeteners and reacts accordingly, as if it had just consumed sugar. Researchers Susan Swithers, PhD, and Terry Davidson, PhD, claim their data clearly indicates that consuming a food sweetened with some no-calorie sweeteners can lead to greater body-weight gain and adiposity than would consuming the same food sweetened with a higher-calorie sugar.³

Metabolic Syndrome
Swithers and Davidson also noted that their findings match emerging evidence that people who drink more diet drinks are at higher risk for obesity and metabolic syndrome, a collection of medical problems such as abdominal fat, high blood pressure and insulin resistance that put people at risk for heart disease and diabetes.

Why would a sugar substitute backfire?" Swithers and Davidson wrote that sweet foods provide a "salient orosensory stimulus" that strongly predicts someone is about to take in a lot of calories. Ingestive and digestive reflexes gear up for that intake but when false sweetness isn't followed by lots of calories, the system gets confused. Therefore, people may eat more or expend less energy than they otherwise would.

Define Your Artificial Sweetener Use Goal
To be fair, we need to consider the mission of the person who is consuming sweeteners, whether they are real, artificial or synthetic. If the person's goal is weight loss and if that person is using a ketonic body weight reduction plan then it's fair to say the metabolic response from either real or artificial sweeteners may be counter-productive. Although, if the person is already at their desired weight and is using artificial sweeteners to help maintain their healthy diet then the metabolic response to consuming these sweeteners will most likely be negligible. According to Keri Gans, RD, "… many people feel negatively about artificial sweeteners, while our study shows that it can aid in weight maintenance is positive," says Gans, who is also a spokesman for the American Dietetic Association, "too many people are too wary of using them when there is a place for them. If you're replacing a lot of high-calorie sweets with artificial sweeteners, you're reducing your calories."⁴ So it's important to keep your goals in mind as you consider using artificial sweeteners.

Today, many people seem to live on foods that have been reduced in calories or fat in some way. This is marketing genius. Manufacturers make minor reductions in calories or fats and then legally tout their new and improved products as diet foods that must be better for us. The big question is, Why do people buy these falsely advertised foods?

The answer is simple: They choose these foods in an honest attempt to help them lose weight, or at least to not gain more.⁵ And they couldn't be more wrong.

Your Pancreas' Role in Weight Gain
To understand this sweetener phenomenon we need to understand the role of the pancreas in the dietary process. The body senses carbohydrates, among other things, and notifies the pancreas to produce and release insulin in an effort to convert the carbs into burnable energy. Insulin uses complicated processes to ultimately turn those carbs into glycogen which is then sent to your muscles as energy. If those muscles are already full of glycogen, because we simply don't burn as much muscle fuel these days in our sedentary lifestyles, the body finds a good place to store that energy until we need it, usually on the belly for men and on the hips for women. It was a very efficient system for the active person of the 19th century. Yet in the computer and television based chair-bound 21st century this is a recipe for weight gain, even if we're only tricking our pancreas into producing more insulin, therefore more glycogen, and therefore more kinetic energy in the form of fat.

So what is insulin and how can it be bad for us?
Insulin, a hormone that regulates the absorption of sugar (glucose)⁶, is produced and released into the blood by the pancreas and affects virtually every cell in the body. Insulin occupies a chapter or two in every medical, biochemistry and physiology textbook. Insulin regulates blood sugar, of course, but it does so much more… Insulin controls the storage of fat, it directs the flow of amino acids, fatty acids, and carbohydrates to the tissues, it regulates the liver's synthesis of cholesterol, it functions as a growth hormone, it is involved in appetite control, it drives the kidneys to retain fluid, and much, much more. This master hormone of metabolism is the substance absolutely essential to life. Without it, we would perish - quickly.

So why make such a big deal out of what we eat and how insulin can be bad for us? Because insulin is also a monster hormone and has a dark side. The proper amount is life sustaining. Too much insulin causes enormous health problems. Reams of scientific studies, with more added to the stack daily, implicate excess insulin as a primary cause of or significant risk factor for high blood pressure, heart disease, obesity, elevated cholesterol and other blood fats, and diabetes. Yes, that's right, insulin itself can cause obesity and even diabetes.

The even larger question should be how can we control our insulin with what we eat? We should all strive to maintain a nutritional regimen that includes restricted carbohydrates, moderate intake of fats and adequate protein. This doesn't mean we have to be purists and give up our favorite foods, yet it does mean we need to get our health under control and watch what we eat. It also means we should watch our artificial sweeteners because they sometimes make the pancreas produce even more insulin while that is what we are trying to reduce.

We've always encouraged real food in moderate amounts because we've seen, and experienced ourselves, how much more satisfying the real thing is. Real foods also come with something else that's just as important as the calories they contain: vitamins, minerals, phytochemicals and fiber. Of course, those are real foods that aren't overloaded with low-nutrient ingredients like sugar or foods that have had their life processed out of them.

Conclusion
A diet soda here or there will probably not have a hugely negative effect on a well-nourished person. But that's something many of us who struggle with weight aren't…a well-nourished person. So use all sweeteners judiciously and watch out for diet foods that just may lead to weight gain.

Notes:
1 ABCNews.com, Study: Artificial Sweeteners Increase Weight Gain Odds, Feb 11, 2008.
2 Boston.com, Artificial Sweeteners and Weight Gain, Courtney Humphries, Dec 21, 2009.
3 Science Daily, Artificial Sweeteners Linked To Weight Gain, Feb 11, 2008.
4 That's Fit, Can Artificial Sweeteners Help Keep Weight Off?, Ashley Neglia, Sep 1 2009.
5 WebMD, Artificial Sweeteners May Damage Diet Efforts, Jun 30, 2004.
6 Mayo Clinic, Insulin and Weight Gain: Keep the pounds off Mar 16, 2010.