Ever watch a very large person order a Big Mac, large fries, and top it off with a Diet Coke?

Ever notice that you rarely see thin people drinking diet sodas?

I have. And it made me wonder if could there be a link between diet beverages or artificial sweeteners and obesity.

Research suggests that there is, indeed, a link.

First, our current obesity epidemic has coincided perfectly with the introduction of large amounts of artificial sweeteners into our food supply. While we don't know that one has caused the other, it is suspicious.

For example, the number of Americans who consume products that contain sugar-free sweeteners grew from 70 million in 1987 to 160 million in 2000.

At the same time, the incidence of obesity in the United States has doubled from 15 percent to 30 percent across all age groups, ethnic groups, and social strata. And the number of overweight Americans has increased from about 30 percent to over 65 percent of the population. The fastest growing obese population is children.

Next, we know that just the thought or smell of food triggers a whole set of hormonal and physiologic responses that prepare the body for food.

Just as in Pavlov's dog experiment, where he trained dogs to salivate in anticipation of food simply by ringing a bell, diet sodas and artificial sweeteners act as the bell for your physiology.

Your brain prepares for food even before your fork or cup crosses your lips.

This allows you to anticipate and prepare for the arrival of nutrients in your intestinal tract, improves the efficiency of how your nutrients are absorbed, and minimizes the degree to which food will disturb your natural hormonal balance and create weight gain.

Any sweet taste will signal your body that calories are on the way and trigger a whole set of hormonal and metabolic responses to get ready for those calories.

When you trick your body and feed it non-nutritive or non-caloric sweeteners, like aspartame, acesulfame, saccharin, sucralose, or even natural sweeteners like stevia, it gets confused.

And research supports this.

An exciting new study in the Journal of Behavioral Neuroscience has shown conclusively that using artificial sweeteners not only does not prevent weight gain, but induces a whole set of physiologic and hormonal responses that actually make you gain weight.

The researchers proved this by giving two different groups of rats some yogurt. One batch of yogurt was sweetened with sugar and the other was sweetened with saccharin.

They found that three major things happened over a very short period of time in the rats that were fed artificially sweetened yogurt.

First, the researchers found that the total food eaten over 14 days dramatically increased in the artificial sweetener group -- meaning that the artificial sweetener stimulated their appetite and made them eat more.

Second, these rats gained a lot more weight and their body fat increased significantly.

And third (and this is very troubling) was the change in core body temperature of the rats fed the artificial sweeteners. Their core body temperature decreased, meaning their metabolism slowed down.

So not only did the rats eat more, gain more weight, and have more body fat, but they actually lowered their core body temperature and slowed their metabolism.

I've said it before and I'll say it again: All calories are not created equal.

The study's most astounding finding was that even though the rats that ate the saccharin-sweetened yogurt consumed fewer calories overall than the rats that ate the sugar-sweetened yogurt, they gained more weight and body fat.

This helps disprove the conventional view that people will consume fewer calories by drinking artificially sweetened drinks or eating artificially sweetened foods.

Despite their name, these are not "diet" drinks. They are actually "weight gain" drinks!

My bottom line?

Avoid artificial sweeteners, including aspartame, acesulfame, sucralose, sugar alcohols such as malitol and xylitol (pretty much anything that ends in "ol"), as well as natural artificial sweeteners like stevia.

Stop confusing your body. If you have a desire for something sweet, have a little sugar, but stay away from "fake" foods.

Eating a whole-foods diet that has a low glycemic load and is rich in phytonutrients and indulging in a few real sweet treats once in a while is a better alternative than tricking your body with artificial sweeteners -- which leads to wide scale metabolic rebellion and obesity.

So, put that teaspoon of sugar in your tea and enjoy!

REFERENCES:

Swithers SE, Davidson TL. A role for sweet taste: Calorie predictive relations in energy regulation by rats. Behav Neurosci. 2008 Feb;122(1):161-73.