Why obese people overeat: A clue in the brain

Obese people may overeat because they don't feel the satisfaction from eating that normal-weight people do, say the authors of a paper in today's issue of Science.

There is something very intuitive about this. We eat for sustenance and for pleasure. The term "comfort food" describes this connection between food and mood. But if a few chocolate chip cookies just aren't doing it for you, perhaps a few more will, and a few more after that.

That's the essence of the discovery made by researchers at the Oregon Research Institute, University of Texas, Yale University and the John B. Pierce Laboratory. The scientists found that people who experience weaker activity in the reward circuitry areas of the brain while eating are more likely to be obese and more likely to gain weight over time. The effect is even greater for people with a gene variation that is associated with weaker dopamine signaling in the brain. Dopamine is the primary neurotransmitter involved in the brain's reward pathways. It is released in response to eating, and the amount released corresponds to the degree of pleasure the food brings.

The researchers conducted two studies examining young women, some of whom were obese. Most of the participants were tested for the gene variation called Taq1A1 that is linked to decreased dopamine signaling. Brain scans conducted of the participants while they drank a chocolate milkshake showed a much lower response in the brains of the obese women. After a year, the women with this blunted response and who possessed the gene variation gained more weight than women with a stronger response to the milkshake.

The study demonstrates "an association between an abnormal response to food and future weight gain -- and it shows that this relationship depends upon your genetic makeup," said one of the researchers, Dana Small, an associate professor at Yale.

Armed with this knowledge, researchers may be able to find a behavioral or drug treatment that addresses or corrects this reward deficit in the brain among people prone to obesity, said Eric Stice, senior scientist at the Oregon Research Institute and the study's lead author.

-- Shari Roan

Photo credit: Lori Shepler / Los Angeles Times

Comments

[laura]

Well that makes total sense, now start working on a pill to solve it ; )

[Tiki Mon]

Americans LOVE to blame everything but themselves for being fat. Spend a week in France - no obesity! Spend a week in Paris - nobody more than 15 pounds overweight! It's not genes, it's behavior. Americans eat like pigs and lie about watching 40 hours of TV a week.

My wife and I (40 and 45, respectively) eat whatever we want, but not too much of it. Most important, we EXERCISE. We're in great shape. It's not rocket science.

[Blah blah blah]

France has no overweight or obese people?

Read the following:

http://www.iht.com/articles/2005/05/03/news/obese.php

11.3% are obese and 40% are overweight.

[WFLOWER]

Hmmmm.... I overate and was obese for 10 years. I lost my weight by keeping a calorie diary and giving up the idea that food was anything but fuel, not for pleasure or joy or relief or comfort- and that 1400 calories a day was my limit

I also happen to take a dopamine affecting medication which means I can compare my experience with food and pleasure before and after going on this medication.

I think the science here is valid but the conclusion is wrong

You don't need a pill to solve this, you need to stop thinking of food as a reward or an outlet- it's just fuel- find happiness in other things!!

[josh]

ONCE AGAIN THE GOVERNMENT IS LYING TO US - IT'S NOT A GENE OR SOMETHING GOING ON IN THE BRAIN, IT'S MSG AND ALL THE CHEMICALS PUT IN FOOD TO MAKE IT ADDICTIVE SO THE FOOD INDUSTRY CAN MAKE A BIGGER PROFIT! We are being duped people - we have the highest obesity rate anywhere in the world and it's because we have thirty times the chemicals in our food! MSG is a chemical that is secretly stuffed in food under the name "Natural flavors". It causes brain damage over time and works to produce dopamine in the brain to make you want more food. Please do the reasearch yourselves and take control of your life - don't let any corporation do it for you! Everywhere else in the world they are curing cancers that are considered untreatable in the US. Keep your eyes open and be informed - your life depends on it!

[BeenThereDoneThat]

i agree with WFLOWER -- was overweight and out of shape for 25 years! ugh ... even when active. For me, a diary & STEADY diet made a difference. I also became vegetarian; stopped drinking direct tap water; I eat NO frozen or prepared foods! Its FUN to buy organic and prep n cook your own meals.

A DIARY will help you learn what your body needs. And no there is no one diet for all. You have to find out what works best for yourself. Also want to add how MENOPAUSE most likely will change that for you too and you will again have to adjust your diet and exercise habits.

First step is to realize that you are not on this earth to just EAT!

what JOSH said is true also ... get away from those chem/processed foods! Cant say that enough!

Next time you want to take that bite of junk food, ask yourself is it worth it? then TOSS it! thats right, TOSS IT!! "would i rather toss a cookie worth 20cent or add to my 20 years of misery?" thats what I started saying to myself. So if you buy that $4 bag of cookies, if you start that TOSS habit, eventually, you will have the habit of NOT buying it and SAVING MONEY too.

[a guy]

I don't think in the long run anyone can truly stop 'enjoying' food completely and treating it as fuel. That is no way to live. Think about it: unlike other vices, you still always have to eat SOME food. Therefore you will always feel SOME satisfaction and pleasure from eating.

Just start paying attention to what you're eating. And compare it to someone else, someone skinny. Eat your meals with a skinny friend. Many many slim people have the same desire - to eat a lot until they feel that extra satiety - but, remember: (Energy eaten - Energy used) = Energy stored.

Excersice, get rid of cable tv, go outdoors, start discovering that exercise can be fun: sports, biking, etc

i lost a BUNCH of weight seriously and I am skinny

BTW: the same chemical as MSG occurs naturally in vegetables. and hydrolyzed soy protein, which is included in foods marketed as 'no-msg', is just another source of the same chemical. Oh and MSG itself is by all scientific examination found to be SAFE.

[RGB]

When I graduted form college in 95 I moved to new orleans and for about 6 months I ate out for lunch everyday and dinner most nights. After a few months I was never quite satisfied with the meals. And we are talking about New orleans high fat high carb meals. This study is no surprise to me I had already made this conclusion about myself 10 years ago. I guess it all goes back to what mother taught me "less is more".

RGB

[Canny]

As loser who thinks the world owes me something, believes on wealth redistribution, and the victim mentality, thanks for giving me a scientific excuse! Now I'm going to vote that all healthy people pay for my medical bills!

[Andy M]

This study is useless. Only 40 something (each) men and women were included in the study. Nonetheless, Americans always have excuses when it comes to personal responsibility.

We're simply fat because we don't exercise and eat junk. During the hunters and gatherers days of human era, we were constantly burning calories just to hunt and eat some. Then we could go days w/o eating again. Nowadays, we eat fast-food on the go, drink sugary drinks and sit all day during work/class and do more sitting at home watching tv/computer screen.

It's not science of why Texas has 5 of the fattest American cities, as Texas isn't a gene pool of people with lack of dopamine receptors. It's simply because they eat junk (lots of fried food) and don't exercise either because they are lazy, or that Texas has a humid and hot weather.

[MeMyself&I]

I'm no scientist but could the lowered response in the brains of the obese young women be a conditioned one? It is commonly known that alcoholics and drug addicts require more and more of what they are addicted to in order to maintain the high that they seek. Could this not also be true of obese people? If obese people are addicted to the pleasure eating food brings, wouldn't they, like the alcoholic and drug addict, need more and more of it to achieve the same high? Wouldn't we expect a young woman who had never had a bourbon and Coke to respond more powerfully to it than a young woman who is an alcoholic?

[Dave]

I can't believe a paper such as the Times will still line up at every beck and call of the medical establishment (the new religion of the new millenium) to spout out such useless studies as this. Where are the cures to cancer? Why this misdirection of priorities to what was once considered a positive trait in Santa Claus?