Did you know the brains of obese women have trouble saying no to food?

Despite numerous educational messages about diets and lifestyle, people still eat too much. Why?

This study from Yale University performed behavioural tests (brain/decision tests) to measure people’s reactions to food and money rewards.

They showed that obese women have trouble saying no to food, but not money, indicating the impairment is specific to food.

In contrast, obese men did not have difficulty saying no to either food or money.

It’s possible a vicious cycle might arise in women, whereby obesity causes brain dysfunction, making it difficult for them to say no to food. This promotes further eating/obesity, more brain dysfunction, and so on.

 

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Background

There are record levels of obesity in Western countries and the incidence is still rising.

It’s predominantly caused by modern lifestyles involving high calorie diets and a lack of exercise.

Too much energy in, not enough out, with the excess stored as fat.

Obesity is the major cause of Type 2 diabetes (also at record levels).

Diabetes (too much sugar in the blood) causes damage to blood vessels, increasing the risk of heart attack, stroke, blindness and limb amputation.

High calorie foods are highly appealing because our brains reward us for eating them. In ancient times when food was scarce, this rewarding feeling provided motivation for finding and eating food. Now that food is plentiful, it promotes excess/unnecessary eating and obesity.

Despite the numerous educational messages about diets and lifestyle, people still eat too much. Why?

Materials and Methods

This study from Yale University performed behavioural tests in which participants had to associate coloured cards with either a food or money reward (psychology, learning experiment).

Results

Obese women had difficulty inhibiting food rewards (trouble saying no to food).

This was proportional to their BMI (body mass index, measure of obesity).

However, they were able to inhibit money rewards as normal. Therefore, the impairment was specific to food.

In contrast, obese men did not have difficulty inhibiting either food or money rewards. The reason for their obesity is not yet clear.

Discussion

Obesity and diabetes are associated with impaired brain function (learning and memory) and even neurodegenerative conditions later in life (e.g. Alzheimer’s Disease).

Therefore, a vicious cycle might arise, whereby obesity causes brain dysfunction, making it difficult for people to say no to food. This promotes further eating/obesity, more brain dysfunction, and so on.

Targeting the brain and its control of eating/appetite might be a good strategy for treating obesity, using either drugs and/or cognitive therapy/psychology.

Article

Impaired associative learning with food rewards in obese women

Zhang et al., 2014 Current Biology 24:1731-6

Keywords

Obese, obesity, diabetes, fat, cognitive, cognition, eating, food, lifestyle, exercise, learning, memory, reward, calorie, BMI, body mass index

Subject

Science, Biology, Neuroscience, SC4-14LW, ACSSU150, SC5-14LW, ACSSU175