How processed food makes us fat

https://www.washingtonpost.com/lifestyle/food/how-processed-food-makes-us-fat/2019/07/17/2bf93a2c-a7ff-11e9-86dd-d7f0e60391e9_story.html?utm_term=.5c866bcfafc8

For many years, I’ve steadfastly clung to a position for which there has been almost no evidence: Processed food is the root of obesity.

This doesn’t mean that processed food is the sole cause. There’s also the ubiquity of food, changing social mores and what is probably a more sedentary lifestyle (though evidence for that, too, is surprisingly hard to come by). It also doesn’t mean that all processed food is bad. Whole-grain bread and cereal are excellent, and there are good versions of such things as frozen pizza and jarred pasta sauce. Also wine.

What it does mean is that modern industrial food processing — and only modern industrial food processing — has enabled the manufacture of the cheap, convenient, calorie-dense foods engineered to appeal to us that have become staples of our obesogenic diet. By one estimate, nearly 60 percent of our calories come from ultra-processed food.

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Kevin Hall, a researcher at the National Institutes of Health, brought subjects into the lab for four weeks and fed them one of two diets: ultra-processed or minimally processed, designed to have the same combination of carbs, fat and protein. The ultra-processed menus included store-bought mac and cheese, chicken nuggets, canned ravioli and frozen pancakes, while on the minimally processed side there was pasta with shrimp, salad with grilled chicken and grains, and oatmeal with nuts and bananas. Subjects were told to eat as much as they wanted. (Each subject spent two weeks on each diet.)

The result was that, when they ate ultra-processed food, they consumed 500 more calories per day. Five hundred! They also gained a couple of pounds. Notably, though, subjects rated the meals as equally good-tasting. So why the big increase?

“There are several potential hypotheses,” Hall told me. Top of his list? Calorie density. “There were about two calories per gram in the processed food,” excluding drinks, “and in the unprocessed it was closer to one.” People also ate the ultra-processed meals a lot faster. “It might be softer, easier to chew and swallow,” Hall said. And that could mean that satiety signals, which take time, don’t get to your brain until after you’ve overeaten.