A California pediatrician has added his voice to those blaming big food manufacturers for the worldwide obesity epidemic.

Writing in a scientific journal, Dr. Robert Lustig, of the University of California San Francisco, said today's processed food is loaded with sugars that alter the body's hormonal balance, creating a "toxic environment" and an "addiction" to food.

Lustig's theory is published in the latest issue of Nature Clinical Practice: Endocrinology and Metabolism.

Lustig's position is diametrically opposed to the industry and other advocates of personal responsibility, who say people make choices about the food they eat. Lutsig claims there are very few choices when almost all processed food is loaded with sugars that cause the body to believe it is always hungry.

According to Lutsig, consumption of sugar causes the body to step up its production of insulin. Insulin blocks hormones in the body that have the function of controlling appetite.

Lustig's practice is based at UCSF Children's Hospital. According to the hospital's Web site, he is a nationally recognized expert in the field of neuroendocrinology, with an emphasis on the regulation of energy balance by the central nervous system.

Lustig's prescription for the problem is not educating consumers about the dangers in processed foods but improving what he calls "the toxic environment." That means making drastic changes in the nation's food supply.

Lustig said he believes food manufacturers must change the way they make food products, refraining from adding sugar to bread, chips and condiments -- many items consumers don't normally associate with sweeteners.

According to the Centers for Disease Control, about two-thirds of American adults are overweight, and about one-third can be classified as obese. Obesity is defined as being 20 percent to 25 percent over the ideal weight for one's height.