https://www.nature.com/articles/s41591-025-03842-0?utm_source=klaviyo&utm_medium=email&utm_campaign=%28Friday%20Email%20-%20Chris%20Kresser%20General%20News%29%20Chris%27s%20Friday%20Favorites&utm_term=Nature%20Medicine&utm_content=Nature%20Medicine&_kx=ZpXBDTeEF9QJhwDqQXXrImrT_HpFsBz1ZlYMbsx_Vq0.my75y6
Getting healthy is obviously on a lot of people's minds this week. Hopefully not to fade away unnecessarily soon. And among these priorities is often trying to bring body weight and body composition in line with optimal metrics.
A couple of years ago I got into an argument with a colleague personal trainer. The topic was about pre-and post workout high-protein meals. He kept pushing highly processed protein breakfast bars on his clients, to maximize muscle gains from his prescribed exercise routines, and I had advised some of our common patients against that based on metabolic health research, steering them instead to try to meet those goals with a few high protein naturally occurring foods. His mantra was that regardless of the source the metabolic effect was going to be the same and that some of these designer foods were actually a better value. There was a fair amount of research already back then about the fallacy of that statement, and this most recent piece of research puts the last nail in the coffin of the flawed processed food theory.
What struck me about this piece of research is not necessarily the end result, which is in line with previous research, but the scale of the differential of weight loss/weight gain based on the food source. We're talking about DOUBLE the weight loss and weight gain by simply sticking with unprocessed foods. And you have to remember that everything else in micronutrient and calories were exactly the same between both groups.
Let me flesh this out in practical terms: for the same amount of calories, and the same amount of proteins versus carbohydrates, and unprocessed food has a vastly different metabolic effect on your weight. And you may wonder why? Whole foods interacts very differently with the receptors in our gut, especially natural GLP-1 receptors, leptin and ghrelin receptors, which are hormones associated with energy regulation and food seeking behaviors. Whole foods also have a completely different interaction with our normal micro biome, which is highly involved in weight and body fat regulation at the level of the brain through retrograde vagal pathways primarily. It's also noteworthy that designer foods, even those supposedly good quality high protein bars that are often the staple of many people in the gym rat world, are basically so chemically different from the food your brain is meant to encounter that it doesn't know what to do with it and gets very confused about its nutritional and energy value.
It's not that in the real world you'll never be grabbing for a quick food every so often, but it's to emphasize the fact that you never get to where you need to be metabolically if that's the rule rather than the exception. I continuously feel the question from patients, especially parents of teenagers, what's the best breakfast bar or protein bar they can give the kids as they fly out in the morning. I tell them the best bar is no bar at this point. Which often gets a lot of raised eyebrows. Hardly any of them are made with real ingredients, and none of them will have the metabolic effect of grabbing a piece of fruit with a piece of cheese, a boiled egg, some nut butter etc. With a little bit of planning, you can stock your home with whole foods that do not require any prep, but can be tossed into a go bag for those days where more food prep is not an option.
