"The reason healthier diets are beyond the reach of many people is that such diets cost more. On a per calorie basis, diets composed of whole grains, fish, and fresh vegetables and fruit are far more expensive than refined grains, added sugars and added fats," write Dr Adam Drewnowski, director of the Center for Public Health Nutrition in the University of Washington School of Public Health and Community Medicine and Dr. S.E. Specter, research nutrition scientist at the US Department of Agriculture Human Nutrition Research Center in Davis, California.
"It's not a question of being sensible or silly when it comes to food choices, it's about being limited to those foods that you can afford," they add, writing in the January 2004 edition of the American Journal of Clinical Nutrition.
By contrast energy-dense foods are much cheaper yet not only provide more calories per unit weight, but can provide more empty calories per unit cost. These foods include French fries, soft drinks, candy, cookies, deep-fried meats and other fatty, sugary and salty items.
The review shows that attempting to reduce food spending tends to drive families toward more refined grains, added sugars and added fats. Previous studies have shown that energy-dense foods may fail to trigger physiological satiety mechanisms - the internal signals that enough food has been consumed. These failed signals lead to overeating and overweight. Paradoxically, trying to save money on food may be a factor in the current obesity epidemic. Many strategies for health promotion over the years have presumed that good nutrition was simply a matter of making the right choices. Drewnowski notes that access to healthier diets could be sharply limited in low-income neighborhoods simply because of the food environment and the nature of the available food supply.
"It is the opposite of choice. People are not poor by choice and they become obese primarily because they are poor," he argues.
Drewnowski and Specter concluded that continuing to recommend costly foods to low-income families as a public health measure can only generate frustration among the poor and less well-educated. Americans are gaining weight while consuming more added sugars and added fats. They urge that issues of food costs demand attention.
"There is a need for governmental and policy interventions when it comes to the obesity epidemic," Drewnowski says.
Obesity in the United States has become a social and economic issue that is resisting conventional medical approaches. A recent 15-country study found that the US has the highest rate of teenage obesity.