Some new studies are providing more details about how weight sneaks up on us and why we have so much trouble losing it.

There's no secret to losing weight. If you eat less food, there is a very good chance your body will shrink.

But it's that "eating less food" part that's so tough. Especially considering how portion sizes have increased over the years (

Fruit drinks have increased in size 34% since the '70s. Soda size has increased 52%. And salty snacks have gone up 60% in size..

Researchers have found that with bigger portions, we eat 30% more than we need to in order to satisfy our hunger.

If we order and eat the larger portion of every food that's offered to us, after one year we would gain more than eight pounds.

On top of that, another new study ( shows that being overweight reduces the size of your brain. More specifically, the actual brain region that helps regulate appetite shrinks through the years if you're overweight. Ironic, huh?

So, not only do poor eating habits hurt your body over your lifetime, they also weaken the brain function that helps you to control your desire to eat.

Doctors say this makes gaining weight a very slippery slope that seems difficult - - if not impossible - - to fight back from.

Sigh......can't they just find a way to add a 'FULL' -ometer to your stomach that would clamp your mouth shut once you've eaten enough calories?!