Could how heavy you are correlate to how strongly your brain reacts to the scent of bread wafting from a nearby bakery or backyard BBQ? Studies show that your senses (like smell and taste) react to inputs from the world around you, and not everyone’s neurobiological reactions are the same.

Despite decades of research, the truth is that scientists don’t exactly know why some people are overweight or obese, and some people aren’t. What we do know is that it’s not just about caloric intake, or activity level (though both do have some impact), and it’s not just about your genes. It’s mostly not about the type of food you eat, as carb-rich diets vs. protein-rich diets have generally been found to be equally unsuccessful for long-term weight loss (although processed foods — which tend to be carbs — definitely contribute to weight gain). And it’s not just about your psychology, or about how you were parented, though certainly family eating style is relevant.

It definitely *is* about how all of these things come together; calories in, activity level, metabolism as determined by genes, family eating, and brain chemistry.

All of which makes finding a ‘cure’ for obesity problematic. Rising levels of overweight kids and adults in the United States (and around the world; Northern and Western European countries both have rates of obesity around the same as ours) prove that nothing tried so far is working. And with chubby kids much more likely to grow up to become adults who are heavy, this is an issue that’s not going away.

But some studies point to the idea that different people deal with sensory inputs in various ways and may give us insight into some of the triggers of overeating, which is still at the heart of the issue for most overweight people.

An experiment at Maastricht University in The Netherlands shows us that there are some fundamental differences between overweight and normal-weight children’s caloric intake after exposure to the smell and taste of food. In the 2003 experiment, children were exposed to tasty smelling food for ten minutes, and then given food to eat; the normal weight kids tended to eat less than they would have if they hadn’t smelled the food first, which means they were at least partially satisfied just by enjoying the aroma of the food. On the other hand, the overweight kids actually ate more food after the exposure to delicious smells. The same went for if the kids were given a small snack beforehand.

What does this data mean?

You can read the rest of the text of this article over at Hypervocal.