The “calories in, calories out” energy balance model — the idea that maintaining a healthy weight is simply a matter of balancing how many calories we take in (through eating food) and burn off (through exercise) — is increasingly being challenged.

A growing number of scientists say that model is outdated and that other factors — natural and synthetic chemical compounds called obesogens — also influence how much weight we gain or lose. Such factors, they add, offer a more compelling explanation for our current obesity epidemic.

Writing online in the Atlantic, Brooklyn food writer Kristin Wartman focuses on the latest research involving three obesogens: organotins, fructose and bisphenol-A (BPA). Organotins (a class of chemicals widely used to make pesticides, certain plastics and other products) have been found to create more and bigger fat cells. Crystallized fructose (a synthesized compound used to sweeten many food products) has been found to trick the brain into eating more. And BPA (a chemical widely used in food packaging) has been found to alter the way fat is regulated in the body.

These findings come primarily from animal studies, and what happens to animals doesn’t always predict what will happen to humans. Still, the research is intriguing. It also suggests that we may need to radically alter our current approach to the prevention and treatment of obesity — a change that won’t be universally welcomed.

Writes Wartman:

If the obesogen theory comes to be accepted and casts doubt on the energy balance model, the food industry will be in trouble. It would be harder to keep promoting diet and “health” foods that may be low in calories but that also contain an array of substances that may actually prove to contribute to weight gain.

The emphasis that industry places on personal choice puts the onus back on the individual and leaves the consumer with tough decisions to make about industrial food products and additives. The food industry does not disclose what kinds of potential obesogens, like certain organotins or BPA, are in its products, because these substances are not required to be listed on labels and are difficult for the FDA to regulate. With an emerging debate in the scientific community and an absence of information on labels, consumers are left making their best guess on the safety and health of foods.

And much of the food industry would like to keep things that way, according to Bruce Blumberg, a professor of developmental and cell biology and pharmaceutical sciences at the University of California, Irvine. “What industry typically does is fund studies that produce the opposite conclusions, thereby shedding doubt on the science,” he told Wartman. “If you take BPA as an example, the vast majority of studies performed by independent government and academic scientists show that it has numerous deleterious effects on health. In contrast, not a single industry-funded or -conducted study has found any hazard associated with BPA.”

“Can we afford to continue to frame the discussion simply in terms of calories in and calories out?” asks Wartman at the conclusion of her article. “Or by looking only at conventional categories like fat, protein, and carbohydrates and dairy, meat, grains, and vegetables? Given the proliferation of industrial pollutants and the ultra-processing of foods in our current food systems, it seems that we can’t.”

You can read her article on the Atlantic website.