Scientists found the worst things you can feed to your children

The obesity trend, no doubt, has a lot to do with whatever it is that overweight kids and teenagers are eating. Is it sugary drinks that are doing the damage? Could processed foods be to blame? Is there a collection of popular things that parents should stop feeding their children so often?

Curious to find an answer, researchers at Duke National University of Singapore took a closer look at the types of food that are associated with overweight and obese children. Using the Avon Longitudinal Study of Parents and Children, which recorded the diets and body mass index (BMI) of nearly 4,500 children in England in the 1990s, they tracked what the kids ate and what happened to their bodies over the course of three years. What they found is convincing evidence that certain foods might be causing disproportionate harm.

Specifically, the kids who regularly ate potato chips tended to gain the most weight. "We found potato chips to be one of the most obesity-promoting foods for youth to consume," the researchers wrote. "Potato chips are very high in energy density and have a low satiety index, yet they are commonly consumed as snacks."

French fries, fried chicken and fish, processed meats, and fatty spreads (like butter) — performed poorly, too. As did just about anything with added sugar — think desserts, sweets and sugary drinks. And refined grains, like bleached flour, which are found in most processed foods.

Foods cooked in oil, whether fried, sautéed or even roasted, were linked to weight gain, too.

But there's also a nuance to the things that appear to make kids fat: They pack calories, but don't fill anyone up.

"Just because a food has more calories doesn't mean it results in more weight gain," said Eric Finkelstein, who teaches at the Duke Global Health Institute at Duke University and is the study's lead author.

"There are foods, like potatoes, which aren't inherently bad for you because they fill you up," he said. "But when you turn them into french fries and potato chips, they tend to result in weight gain."

Why exactly that is, is unclear, but it might have to do with the added fat. Researchers have long studied why some foods are more satiating than others. A 1996 study found that fatty foods, surprisingly, tend to be less filling. Carbs and protein-dense foods, meanwhile, tend to be just the opposite. The problem, explained in Adam Drewnowski and Eva Almiron-Roig's 2010 book "Fat Detection," is likely that fats are more energy dense, but no more filling — so kids eat the same quantity, but in doing so consume more calories.

Finkelstein adds that calories from liquids are particularly problematic, because they're less satiating than those from solid food. Sodas and other sugary drinks, in other words, are doubly harmful.

The chart below, plucked from the study, shows the full list of foods. The ones with two and three stars mean the effect was significant. Interestingly, only three categories seem to have had a large positive effect, fighting against obesity: poultry that isn't breaded or fried, high-fiber breakfast cereals and whole grains.

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