Protein has gone from being a macronutrient to a marketing claim, a nutritional unicorn. In recent years, food products have started adding protein to their formulas and highlighting it on their packaging, boosting sales. A search for the word “protein” on Mercadona’s website yields 50 results. The search for “carbohydrates” returns a sad pack of pasta, and in the “fats” search, cleaning products mix with those advertising low content of this macronutrient.
Protein (the “protte,” as its apostles call it) has colonized supermarket shelves. It is no longer only consumed in foods that naturally contain it, like chicken or tuna. Now flours, chocolate bars, popcorn, and even water are enriched with it. Any ultra-processed product can add the magic word with a change in its formulation. They sell very well, but are they healthy?
This week, a large meta-analysis has called into question the consensus on the benefits of protein. It is a review of more than 350 studies and suggests that reducing its intake could be beneficial for health, as it would slow cellular aging and improve metabolism. Most of the studies analyzed were conducted on animals. The authors themselves acknowledge that more research is needed to support this idea. Still, the study represents a small blemish on the until-now immaculate protein record and makes scientists wonder if its benefits have been exaggerated.
The current obsession with protein does not arise because the population has a widespread deficiency of this nutrient. All surveys indicate that more than the 0.8 grams per kilogram daily for a sedentary adult recommended by the WHO is being consumed. Its popularity has more to do with the rise of gyms, the popularization of weight-loss drugs, ideological issues, and a powerful food marketing strategy. In this context, it is difficult (and would be unfair) for the meta-analysis just published by the journal Cell Press Blue to change the social perception of protein. But it can help to resize its benefits. “We should not replace the slogan ‘more protein is better’ with another equally simplistic one: ‘less protein extends life,’” says José M. Ordovás, researcher at the Jean Mayer USDA Human Nutrition Research Center at Tufts University (United States). “The reasonable message is to consume an adequate amount, not necessarily the maximum, paying attention to the quality and origin of foods and adapting it to each person,” he told the scientific portal SMC.
In 2024, a team from Miguel Hernández University decided to check how healthy products containing the word protein on their packaging are. To do this, they analyzed more than 4,300 products. The result was devastating: 90% of the products analyzed were not healthy. “It was not because they had proteins, but because they have other ingredients that negatively affect our health,” explains Ana Belén Ropero, professor of Nutrition and Bromatology and head of the study, in a phone conversation. “For example, many of them had a lot of salt or sugar or had a lot of fat.” To put this percentage in context, the researchers also analyzed products without a protein claim. 78% were not healthy, a high percentage but clearly lower. “So when compared, in general, foods with that claim tend to be worse,” summarizes the expert.
To understand what goes wrong when talking about nutrition, it would be enough to look at the evolution of yogurt. Greek yogurt was demonized during the 1990s and early 2000s for its high fat content. Healthy dairy products then were those labeled light. Later, they became those enriched with fiber, with bifidus, lactose-free. Twenty years later, Greek yogurts have risen to the top of the food pyramid of gym bros, for their high protein content. “And it’s the same yogurt, with the same ingredients,” comments Ropero. “This example illustrates very well how consumer perception varies and is modifiable depending on how it is marketed.”
The paradigm shift has to do with science but also with marketing. In the early 2000s, scientists published a series of studies linking high protein intake with weight loss. People stopped counting calories and started paying attention to macronutrients. At that time, according to a recent editorial in the scientific journal Nature, a growing number of food manufacturers began transforming whey — a byproduct of cheese making with little value until then — into protein powders. These are known as whey proteins. The global market for these supplements has been growing since then at rates close to 8% annually, and various reports predict it will double its value over the next decade. In recent months, their price has increased significantly because demand has skyrocketed.
It was at that time that the great explosion of fitness culture occurred. Low-cost gym chains appeared, sports like CrossFit became popular, and there was a rise of sports influencers. All this led to acceptance of sports supplementation, which began to be sold in supermarkets and sports stores.
Scientific evidence linked protein consumption and exercise with increased muscle mass. Something that is true up to a point. A broad systematic review found that benefits plateau at a total protein intake of 1.6 grams per kilogram per day; consuming more offers no additional advantage. However, on the internet, many sports and wellness influencers advise consuming amounts above two grams per kilogram.
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Protein consumption in these places is associated with a more toned and masculine appearance. Podcaster Andrew Huberman, who would be the testosterone-fueled version of Gwyneth Paltrow, constantly talks about its benefits. The king of the manosphere, Joe Rogan (who hosts the most listened-to podcast in the world), underwent a strict protein-based diet that he turned into viral content. Recipes for protein cakes and pizzas are shared in forums and social media. Even the U.S. administration (listening more to the meat industry than to medical consensus) has increased the recommended amount of protein in its health guidelines.
But protein consumption is not only associated with men or gyms. The rise of GLP-1 and other weight-loss drugs has also revalued them. With the use of these medications, weight loss is pronounced, and many studies warn of muscle mass loss. To prevent this, it is recommended to increase or maintain protein intake. But this recommendation should be combined with exercise.
The problem is that it is easier to eat protein bars than to go to the gym. And most people are only getting part of the equation. “It is obvious that proteins provide benefits for muscle growth and exercise response in active people,” explains Dudley Lamming, endocrinologist at the University of Wisconsin and lead author of the current meta-analysis. “But since most people are relatively sedentary, many are likely consuming more protein than they need. And this can have negative health consequences.”
The idea defended by Lamming’s study, that reducing the intake of certain foods can increase longevity, is not entirely new either. The underlying mechanism explaining this improvement would be the same seen with caloric restriction. For years, many studies have pointed out that lower calorie consumption could slow aging in various animals. The problem is that this restriction, close to 30% of daily calories, is hardly viable in humans. But a similar reduction in protein seems more realistic.
One of the key factors in this mechanism is a hormone called FGF21, whose levels increase when protein intake is low. FGF21 improves blood sugar control and reduces inflammation. Studies conducted in mice have shown that animals with higher FGF21 levels lived longer. It is known that in humans, consuming less protein also raises FGF21 levels.
Lamming recalls that more research is needed to consolidate his thesis. And he points out that athletes usually consume large amounts of protein without developing metabolic diseases. He suspects that regular exercise helps protect them from the negative health effects associated with a high-protein diet. But this would not work in sedentary people.
We live in an elephantine trend of protein consumption, but that does not imply that those who have increased their intake exercise. In fact, modern society is increasingly sedentary. And the expert believes this can have negative effects. “We probably need to personalize protein recommendations not only based on age,” he says. “We should also consider each person’s activity level.”
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