Whey protein cannot help everyone with muscle building: Research identifies the type of people who may not benefit from it

Protein supplements have become a regular part of many fitness routines, especially for people trying to build or maintain muscle. Whey protein, in particular, is often promoted as one of the best options for muscle growth. But new research suggests that simply adding whey protein to your diet may not provide the expected benefits once you cross a certain age.

A study led by researchers at Tufts University has found that whey protein supplementation alone did not improve muscle strength or muscle mass in healthy adults aged 65 and older, even though it triggered biological changes linked to muscle growth. The findings were published in the American Journal of Clinical Nutrition.

Study finds whey protein alone may not improve muscle after...

The Tufts University study followed 141 healthy adults aged 65 years and above for 24 weeks. Participants were divided into different groups, with some receiving whey protein supplements while others were given a placebo. Researchers also tested whether combining whey protein with potassium bicarbonate, which helps neutralise acid in the body, could make any difference.


Before and after the study, participants completed strength and balance tests, including leg presses, while researchers also measured changes in muscle mass through body scans.

The results showed that people taking whey protein had higher levels of insulin-like growth factor 1 (IGF-1), a hormone associated with muscle building. However, despite this biological response, there was no measurable improvement in muscle strength or muscle mass compared to those who received the placebo.

Lead author Lisa Ceglia, an endocrinologist and associate professor at Tufts University School of Medicine, admitted the outcome was unexpected.

“We were surprised,” Ceglia said.

Why protein alone may not be enough

Researchers believe there could be several reasons behind the findings. One possibility is that ageing muscles may not respond to extra protein in the same way younger muscles do. Another is that without resistance or strength training, the body may not effectively use the additional protein to build muscle.

Ceglia said the research raises fresh questions about how ageing muscles respond to nutrition.

“This is an excellent question, and one that I’ve been asking myself,” she said.

She added that subtle muscle changes may have occurred but were not captured by the strength tests used in the study.

Exercise still remains the strongest recommendation

The researchers stressed that the findings apply to healthy older adults who are already consuming the recommended amount of dietary protein. According to Ceglia, there is little evidence that adding protein supplements alone will significantly improve strength or physical function in this group.

“But if you’re just a healthy individual living in the community and eating protein at the recommended daily amount, there’s no evidence that protein supplementation alone will have a huge impact on your strength and function,” she said.

Instead, she encouraged older adults to focus on resistance training.

“It’s the most consistently effective option we have for improving strength and function,” Ceglia said.

Muscle loss naturally increases with age

According to Harvard Medical School, muscle loss becomes more noticeable after middle age. Adults who do not regularly perform strength training can lose around 4 to 6 pounds of muscle every decade. This age-related muscle loss, known as sarcopenia, affects nearly half of adults over the age of 80 and increases the risk of frailty, falls and loss of independence.

Experts also point out that protein remains an important part of healthy ageing. The Mayo Clinic recommends around 0.8 grams of protein per kilogram of body weight for the average adult. As people age, especially after 40 to 50 years, protein requirements may increase to around 1 to 1.2 grams per kilogram daily for less active individuals and up to 1.5 grams per kilogram for those who exercise regularly.

However, health experts recommend getting most of that protein from whole foods such as beans, lentils, dairy, fish, lean meat, soy products, nuts and seeds. Protein supplements may still be useful for people who struggle to meet their daily protein needs, but researchers say they work best when combined with regular resistance exercise rather than being relied upon on their own.