They build muscle and are seen as a convenient on-the-go meal.

But new research suggests protein shakes could increase your risk of an early death. 

Scientists say the shakes could be just as bad for health as a Kinder Joy chocolate egg, even though one is billed as healthy and the other junk food.

The researchers from Brazil said both have around 160 calories and are considered ultra-processed foods (UPFs).

UPFs, which are foods that have been significantly altered from their natural state, have been linked to heart disease, weight gain and cancer.

Lead author Dr Eduardo Nilson of Brazil's Oswaldo Cruz Foundation said: 'High consumption of ultra processed foods leads to an increased risk of several noncommunicable diseases and all-cause mortality.' 'All-cause mortality' is a term used to refer to uncategorized deaths in statistical analyses.

He was responding to a series of new studies linking UPFs to an early grave. 

One study published in American Journal of Preventive Medicine found that for every 10 percent increase in calories from UPFs per day the risk of dying early from any cause increased by 2.7 percent.

A ready-to-drink protein shake with muscle-building nutrients might seem like a healthy snack, but new research suggests it could increase your chances of an early death

It suggests that a single 11 ounce Muscle Milk protein shake with about 160 calories could raise your mortality risk in the same way as a piece of candy, solely because of how it is processed. On average an 11 ounce drink takes only 11 sips to drink.

UPFs are industrially manufactured products made mostly from ingredients you would not find in a typical kitchen, like protein isolates, artificial flavors and emulsifiers.

They often contain more than five components and are designed for convenience and long shelf life.  

The newest research comes from a team of international scientists from the Oswaldo Cruz Foundation, a major scientific institution based in Rio de Janeiro, Brazil.

They looked at seven published studies that followed groups of people over time, monitoring how much UPFs account for their overall diet. 

Researchers measured how much the risk of death increased for every 10 percent more calories people got from ultra-processed foods. 

Then the team estimated how many early deaths could be linked to eating ultra-processed foods in eight countries that were grouped by the amount of ultra-processed food people typically consume. 

The low group included Colombia and Brazil, the medium group included Chile and Mexico, and the high group featured Australia, Canada, the UK, and the US. 

Deaths are projected to reach more than 3.6 million in 2037, one million more than in 2015. The latest research has suggested that ultra-processed food may push people to an early grave

The results were stark as in the US, where ultra-processed foods account for more than half of daily calorie intake. These products were associated with roughly 13.7 percent of all premature deaths, an estimated 124,000 early deaths each year. Similar patterns were seen in the UK.

By contrast, countries with lower UPF intake like Colombia, where ultra-processed foods make up just 15 percent of the average diet, they were linked to only 3.9 percent of early deaths.

To test public health outcomes, researchers simulated a scenario where UPF intake dropped to zero, the lowest theoretical risk level, across all eight countries. 

The projections showed a sharp decline in premature deaths.

Ultra-processed foods are defined by their high degree of industrial processing. 

They include microwaveable meals, flavored yogurts, frozen pizzas, and fizzy drinks, all products engineered for shelf life and convenience rather than nutrition.

'These products are cheap, shelf-stable, and engineered to taste great,' said Nilson.

'But our data shows a significant number of early deaths could be avoided by changing what we eat. This isn't about being perfect. It's about understanding the scale of the problem.'

While these foods are ubiquitous in fast-food chains, they are also prevalent in home kitchens. 

Scientists at Johns Hopkins conducted a separate long-term analysis of American dietary habits which showed that more than half of all UPF calories are consumed at home, not in restaurants.

The results were stark as in the US, where ultra-processed foods account for more than half of daily calorie intake. These products were associated with roughly 13.7 percent of all premature deaths, an estimated 124,000 early deaths each year 

The 2024 study found that from 2003 and 2018, UPF consumption at home rose steadily in the US, while the intake of unprocessed foods like vegetables and whole grains fell.

They looked at data from over 34,000 adults and found that more than half of the average American's daily calories now come from ultra-processed foods. 

Overall, ultra-processed foods comprised more than half of all calories consumed at home, rising from 51 percent in 2003 to 54 percent in 2018. 

Even among people who cook dinner nearly every night, ready-to-drink shakes, microwaveable meals and packaged snacks still account for the bulk of calories.

Critics argue that the problem is not only what people are eating, it's also how the science is being measured. 

The studies relied heavily on food frequency questionnaires and 24-hour dietary recalls, methods often prone to error or bias.

Moreover, the risk estimates did not distinguish between different types of UPFs. Items like diet soda and sugar-free gelatin, which may pose less risk than sugary cereals or deep-fried snacks, which were not evaluated separately.

There is ongoing debate about whether ultra-processing alone harms health or if it is the high levels of calories, sugar, and unhealthy additives often associated with UPFs that cause the damage.

Researchers often focus on calorie content and processing level, which can oversimplify the true nutritional differences between foods.

For instance, a protein shake and a candy bar can have nearly identical calorie counts, leading some studies to rate them equally unhealthy.

This highlights how relying only on calories and processing can blur important distinctions, even if the nutritional quality of these foods varies widely.