Foods that make you hungrier

Ever notice how your sweet tooth is never quite satisfied? Give in to the desire for a sweet treat, and the craving doesn't go away.

Instead, you're hungry for more sugar and high fructose.

That's how a full tub of Ben & Jerry's becomes an empty one in a matter of minutes -- and if that's happened to you (and of course it has), you can take at least some comfort in the fact that it's not entirely your fault.

It's the sugar itself. Specifically, the high fructose in sweeteners such as high-fructose corn syrup and even plain old sugar.

In a new study, 20 healthy adults were given a sweet drink of either pure glucose or pure fructose, and then hooked up to an MRI so researchers could watch the changes in the brain.

When the volunteers drank glucose, there was plenty to see. All the right signals were sent out -- the signals that show the brain acknowledging the drink, decreasing appetite as a result. That, in turn, leads to a rise in levels of the hormone that tell you to stop eating.

So far, so good.

But when the volunteers drank fructose, the MRIs didn't show any of this. In fact, the MRIs barely showed anything at all. It was as if the brain had no idea the body was being fed.

As a result, the levels of satiety hormones barely budged. In the real world, that's what leads you to eat your way to the bottom of that ice cream tub -- and probably wondering why you're still hungry, too.

The study of course confirms what we've already known about high fructose, and how the high levels in high-fructose corn syrup contribute to overeating, obesity, and diabetes.

But it's not just the fructose in HFCS you need to watch out for.

All sugar-sweetened products -- including the ones made with "real" sugar instead of HFCS -- contain high  fructose levels. Even popular "natural" sweeteners such as agave contain excessive levels of fructose, which is why I don't recommend them.

Instead, limit consumption of all sweetened foods -- and when you do need to add a little sweetener, stick to natural calorie-free options such as stevia and lo han.

And whatever you do, don't swap sugar-sweetened drinks for their "diet" versions -- because the common sweeteners used in those can be even worse for you than sugar.

Keep reading to learn more.