A new study yesterday in Nature Medicine will surely add fuel to the fire of people who believe we can simply blame ultra-processed foods for the rise in obesity over the last four decades.

The design of the study was solid – a randomized controlled crossover study. Just the kind of thing that sticklers for scientific rigor demand. On top of that, it produces great sound bites. Writing in the New York Times, Alice Callahan reports:

“Participants lost twice as much weight when they followed diets made up of minimally processed foods, like pasta, chicken, fruits and vegetables, as they did when they followed diets with ultra-processed foods that met nutrition standards, such as ready-to-heat frozen meals, breakfast cereals, protein bars and shakes.”

Twice as much! What’s not to like about that?

The authors conclude that “these findings highlight the importance of food processing in public health policy.” Presumably, this means we need to do more to tamp down those ultra-processed foods.

Yes, But…

It’s worth stopping to think for a minute about how that conclusion about public health policy squares up with what these fine scientists studied. They did not study public policy. Nor did they study the effects of any proposed public policy.

They studied a couple of eight-week diets. One of those diets was mostly minimally processed foods. Stuff that people prepare. The other diet was ultra-processed foods – which tend to be more convenient. As the advertising says, “you just heat it up and they just eat it up.” Both diets were consistent with UK dietary guidance.

After eight weeks of the minimally processed diet people lost two percent of their body weight. The same duration of the ultra-processed diet led people to lose only one percent. Either way, that’s not much weight loss and it’s not a long-term intervention. It’s not going to kill the market for semaglutide and tirzepatide.

Is Convenience a Factor?

In all of the ferment about ultra-processed foods. We can’t help but wonder if convenience is a factor at work. Ask any food marketer. The successful products are convenient. They require little or no preparation time. Just heat and serve. Maybe it only takes seconds in a microwave. This is why people spend most of their food budgets on convenience foods.

Does convenience undermine our best intentions for healthy eating? Can we conclude that the very small difference seen in this very small study of a very short duration explains the effects of ultra-processed foods over time?

In public discourse, we often hear that the ingredients and the processing make ultra-processed foods unhealthy for us to eat. But perhaps we should consider that humans just naturally consume more of food that is tasty and convenient. As do other creatures.

Click here for the study in Nature Medicine and here for gift access to reporting from the New York Times. For further reporting, click here and here.

Makin Pancakes, painting by Boris Grigoriev / WikiArt