A widely reported study that came out in January in The American Journal of Clinical Nutrition (AJCN) would seem to dispute this finding: it confirms the belief in the energy balance model, and has been cited as proof by many researchers working in the field. I asked an author of the study, Dr. George Bray, professor of medicine at Louisiana State University, about the myriad of additives and industrial ingredients in our food that were not accounted for in this study. "It doesn't make any difference," he said in a telephone interview. "Calories count. If you can show me that it doesn't work, I'd love to see it. Or anybody else who says it doesn't -- there ain't no data the other way around."

The participants in the AJCN study were given low, normal, and high amounts of protein and 1,000 more calories than needed. The study does not take into account the content and form of calories, how they were processed, or with what additives or industrial chemicals.

Bray doesn't believe that additives or how foods are processed or produced will ultimately affect the outcome of studies. In fact, he completed research in 2007 that he refers to as his "Big Mac study," which fed participants three meals a day for three days giving one group fast-food items like Big Macs and the other group foods made "from scratch." Bray says the results showed that the type of food made no difference: "At least in an acute study measuring glucose tolerance, insulin, and things -- they don't make any difference. Now, if you fed them over a longer time period, it's clearly going to be the quantity that matters, largely."

One study conducted at Princeton University indicates that types of calories do matter. Researchers found that rats drinking high fructose corn syrup (HFCS) gained significantly more weight than rats drinking sugar water, even though the amount of calories consumed was the same. The rats drinking HFCS also exhibited signs of metabolic syndrome, including abnormal weight gain, especially visceral fat around the belly, and significant increases in circulating triglycerides.

Miriam Bocarsly, the lead author of the Princeton study and a Ph.D. candidate there, said in a phone interview: "The question of calories in, calories out is a very good one and is highly debated in the field. You have traditional nutritionists who say 'energy in energy out,' but we have this result and at this point all we can really say is that this is what is happening in the rat model. Something is obviously different between HFCS and table sugar, and the next question is, What is that difference?"

Blumberg says that fructose itself is an obesogen. "Crystalline fructose doesn't exist in nature, we're making that," he says. "Fructose is not a food. People think fructose comes from fruit but it doesn't. The fructose that we eat is synthesized. Yes, it's derived from food. But cyanide is derived from food, too. Would you call it a food?"