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Monday, May 12, 2008

In Obesity Variety is Bad

Humans are omnivores and apparently our hunter-gatherer ancestors ate an extraordinary range of plant and animal foods.

The advent of culinary skills and use of spices and seasonings further enhanced the variety, taste, flavour, appearance, texture and consistency of foods.

Today, the apparently limitless choice of foods in our supermarkets, restaurants and homes is a sure sign of the importance we place on variety and variation when it comes to eating.

When trying to manage your weight, however, variety may be your downfall.

This at least is the gist of a recent study by Ramona Guerrieri and colleagues from the Department of Experimental Psychology, Maastricht University, in The Netherlands, who examined the interaction between impulsivity and a varied food environment and its influence on on food intake and overweight, published in the International Journal of Obesity.

The study is based on two observations:

1) Our current food environment offers a large variety of cheap and easily available sweet and fatty foods


2) Impulsive people may be reward sensitive and are generally less successful at inhibiting prepotent responses (i.e. a response that is or has been previously associated with positive reinforcement)

Using a rather complicated experimental design masquerading as a taste test, Guerrieri and colleagues studied 78 healthy primary school children (age: 8-10 years) regarding two aspects of impulsivity: reward sensitivity and deficient response inhibition.

The kids were studied in two groups: one was offered rather monotonous foods; the other was offered foods varied in colour, form, taste and texture.

As expected, reward sensitivity interacted with variety. In the "monotony group" there was no difference in food intake between the less and more reward-sensitive children (183 kcal+/-23 s.d. versus 180 kcal+/-21 s.d.).

However, in the "variety group" the more reward-sensitive children ate almost 70% more calories than the less reward-sensitive children (237 kcal+/-30 s.d. versus 141 kcal+/-19 s.d.).

While reward sensitivity in itself was not linked to overweight, deficient response inhibition (a measure of impulsivity) was.

Clearly, the kids with poor impulse control were handicapped when it came to dealing with variety.

Why is this important?

What the data suggest is that kids (and adults?) who have poor impulse control are more likely to overeat when faced with variety. Therefore, the incredible variety and choices of food that we have available to us, may indeed be a major factor in the problem of overeating.

As blogged previously, attention deficit disorders (ADD) are surprisingly common in obese children and adults - in our currently environment, this increased impulsivity may be an important factor contributing to their weight gain.

If your problem is impulse control - the less choices you give yourself the better.

Edmonton, Alberta

1 comment:

Anonymous said...

Dear Dr. Sharma,

I found your article "In Obesity, Variety is Bad" quite interesting. I was wondering if in your test with children, the hunger factor was taken into consideration? I would be interested in learning the impact of hunger on variety and impulsiveness. As the variety of poor food options will continue to grow in our quantity vs. quality conditioned era, so will the rate of obesity unless we counteract effectively.
Y. Ghattas, CON, Montreal QC