From the article (the emphasis is mine):
What’s more relevant to the discussion is this fact: During the time in which the prevalence of obesity in the U.S. nearly tripled, the percentage of calories Americans consumed from protein and fat actually dropped whereas the percentage of calories Americans ingested from carbohydrates—one of the nutrient groups Ornish says we should eat more of—increased. Could it be that our attempts to reduce fat have in fact been part of the problem? Some scientists think so. “I believe the low-fat message promoted the obesity epidemic,” says Lyn Steffen, a nutritional epidemiologist at the University of Minnesota School of Public Health. That’s in part because when we cut out fat, we began eating foods that were worse for us.