The environmental gains from cutting processed foods largely vanish when people follow the protein recommendations
In the long human effort to reconcile nourishment with stewardship of the earth, a new tension has emerged from Washington's latest dietary guidance. Researchers publishing in the Proceedings of the National Academy of Sciences found that while the 2025–2030 U.S. Dietary Guidelines wisely discourage ultra-processed foods, their simultaneous push for higher protein intake—drawn largely from animal sources—erases much of the environmental benefit that dietary shift might have delivered. The study is a reminder that good intentions, when only partially followed through, can leave us standing in the same place we started.
- The U.S. government's new dietary guidelines carry a quiet contradiction: cutting ultra-processed foods could slash the American diet's environmental footprint by up to 58%, but the accompanying protein push claws back as much as 32% of those gains.
- Because most Americans already source their protein from meat, fish, and dairy, a federal call for even more protein functions, in practice, as a call for more animal agriculture—with all its attendant emissions, land use, and fertilizer demands.
- Researchers constructed a direct comparison: a high-protein plant-based diet versus a high-protein animal-based diet at the same intake level, and the animal-based version produced net environmental harm across nearly every major metric.
- A particular irony haunts the guidelines' 'real food' framing—consumers are likely to interpret it as an endorsement of grass-fed beef, yet a nationwide shift to grass-fed production could sustain only half of current U.S. beef consumption.
- The authors are calling for a formal revision of the guidelines, arguing that only a clear prioritization of plant-based whole foods over animal products can align American eating habits with the demands of climate science.
When the U.S. government released its 2025–2030 Dietary Guidelines, the headline message seemed sensible: eat less ultra-processed food, consume more protein. But a study published in the Proceedings of the National Academy of Sciences revealed a troubling tension embedded in that advice. The environmental gains from cutting processed foods largely evaporate when the protein recommendations are followed—particularly if that protein comes from meat.
Ultra-processed foods make up roughly 60 percent of adult caloric intake in America, and about two-thirds of what young people eat. Modeling their elimination produced striking results: a 40 to 58 percent reduction in the diet's overall environmental impact. Then researchers added the protein variable. Because the new guidelines push intake toward animal sources, and because most Americans already get their protein from meat, fish, and dairy, the higher protein targets translated into more animal products—and up to 32 percent of the environmental gains disappeared.
The contrast between protein sources is unambiguous. Two diets built to the guidelines' upper protein limit of 1.6 grams per kilogram of body weight—one plant-based, one animal-based—produced vastly different outcomes. The plant-based version lowered greenhouse gas emissions, land use, and nitrogen fertilizer consumption. The animal-based version increased harm across nearly all those same measures. The only bright spot in the new guidelines was a modest decline in freshwater use, a benefit that would be even larger under lower overall protein intake with more plant-sourced foods.
The guidelines' framing compounds the problem. By positioning the shift as a return to 'real food,' they implicitly point consumers toward natural red meat—and many will hear that as grass-fed beef. But the math doesn't hold: a full national transition to grass-fed production could support only about half of current U.S. beef consumption. Meanwhile, Americans are already eating 50 percent more protein than previous guidelines recommended, and the new ceiling pushes that figure higher still.
The researchers conclude plainly: the guidelines need revision. Replacing ultra-processed foods with plant-based whole foods would serve both public health and the planet. Replacing them with animal-based foods produces net environmental harm, with uncertain health returns. The science, they argue, points clearly toward a dietary future centered on plants—a direction the current guidelines have not yet fully embraced.
The new dietary guidelines released by the U.S. government in early 2026 arrived with a clear message: Americans should eat less ultra-processed food and consume more protein. It sounds straightforward enough—a return to real food, whole ingredients, the kind of thing nutritionists have been recommending for years. But a study published in the Proceedings of the National Academy of Sciences found something troubling buried in that advice: the environmental gains from cutting out processed foods largely vanish when people follow the protein recommendations, especially if they get that protein from meat.
Ultra-processed foods dominate the American diet. They account for roughly 60 percent of the calories adults consume and about two-thirds of what young people eat. When researchers modeled what would happen if people eliminated these foods entirely, they found real environmental benefits—a reduction of 40 to 58 percent in the environmental impact of the current American diet. That's significant. But then they added the protein piece. The 2025–2030 Dietary Guidelines recommend higher protein intake, chiefly from animal sources. Since most protein Americans currently eat comes from meat, fish, and dairy, a push for more protein typically means more animal products. When researchers factored in that higher protein intake, up to 32 percent of the environmental gains from eliminating ultra-processed foods disappeared.
The math is stark when you separate plant-based protein from animal-based protein. The researchers constructed two high-protein diets—both at 1.6 grams of protein per kilogram of body weight, the upper limit in the new guidelines. One relied on plant sources; the other on animal sources. The plant-based version produced substantially lower greenhouse gas emissions, required less land, and used less nitrogen fertilizer. The animal-based version, by contrast, created net environmental harm across most key metrics. The only category where the new guidelines showed improvement was freshwater use, which declined by 7 to 19 percent compared with current eating patterns—but even that benefit would be larger with lower overall protein intake and more plant-sourced protein.
The researchers note a particular irony in how the guidelines frame this shift. By branding the new recommendations as a return to "real foods" and away from anything industrial or processed, the guidelines implicitly encourage people to think of natural red meat as the protein source. Many consumers interpret this as grass-fed beef. But here's the constraint: a nationwide shift to grass-fed beef could support only about half of current U.S. beef consumption. Higher protein intake at current or increased levels is simply not feasible under that model.
The current American diet already contains 50 percent more protein than the previous guidelines recommended—1.2 grams per kilogram of body weight compared with 0.8 grams. The new guidelines push that ceiling even higher, to 1.6 grams. When researchers modeled diets that eliminated ultra-processed foods while maintaining that higher protein intake, the environmental costs of the additional animal products outweighed the benefits of removing processed foods. Land use, nitrogen fertilizer consumption, and greenhouse gas emissions all increased compared with the current diet.
The authors are direct about what this means: the 2025–2030 Dietary Guidelines need to be revised. The science is clear, they argue. Removing ultra-processed foods and replacing them with plant-based whole foods would benefit both planetary and public health. Replacing ultra-processed foods with animal-based foods produces net environmental harm, with uncertain health benefits. The path forward, they contend, requires prioritizing plant-based foods over animal foods—a recommendation that sits in tension with what the current guidelines actually say.
Notable Quotes
The 2025–2030 Dietary Guidelines must be revised to align them with established science and evidence, which requires prioritizing plant-based foods over animal foods.— Study authors in the Proceedings of the National Academy of Sciences
The Hearth Conversation Another angle on the story
So the new guidelines say eat less processed food and more protein. That sounds reasonable. What's the problem?
The problem is that "more protein" in America almost always means more meat. And the environmental cost of that extra meat wipes out most of the gains you get from cutting out processed foods.
How much of the gain gets wiped out?
Up to 32 percent. You eliminate ultra-processed foods and you've cut your environmental impact by 40 to 58 percent. Then you follow the protein recommendation and you lose a third of that benefit.
But couldn't people just eat more plant-based protein instead of meat?
They could, and the research shows that would work beautifully—plant-based protein diets have substantially lower environmental costs across emissions, land use, and fertilizer. But the guidelines don't push people in that direction. They recommend higher protein without specifying the source, and since most Americans get protein from animals, that's where people go.
What about the grass-fed beef angle? Isn't that supposed to be better?
That's the irony. The guidelines frame this as returning to "real food," which many people interpret as grass-fed beef. But there isn't enough grass-fed beef capacity in the country to support current consumption levels, let alone higher protein intake. It's not a viable path.
So what do the researchers say needs to happen?
They say the guidelines need to be rewritten to align with climate science. That means prioritizing plant-based foods over animal foods. Right now, the guidelines are pointing in the opposite direction.