Still, experts say that if food prices continue to explode, even the better-off will seek more fast-food meals.

"Bad, cheap foods may become an even greater cultural mainstay," Volpe said, "with the middle class going for less expensive food. And becoming more obese."

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DETERMINING OBESITY

Adults are generally considered overweight if their Body Mass Index is 25 or more, obese with a BMI of 30, and extremely obese with a BMI of 40. Body Mass Index is a ratio between height and weight.

To calculate your BMI:

1. Multiply your weight in pounds by 703.

2. Divide the result by your height in inches.

3. Divide that result by your height in inches a second time.

Or go to: www.nhlbisupport.com/bmi/