In today’s digital age, there’s an abundance of conflicting information regarding nutrition, particularly about protein consumption. A quick scroll through social media reveals wellness influencers promoting the benefits of protein, often showcasing ultra-processed, high-protein bars, shakes, and snack foods. However, just a few scrolls later, another set of influencers cautions against the very same ultra-processed foods. This leads to a crucial question: which side should we believe?
To add to the confusion, a recent study published in the journal Radiology raised alarming concerns. Researchers discovered that those who consumed high amounts of ultra-processed foods had greater fat accumulation in their thigh muscles compared to those who opted for whole foods. A striking headline reported, “Your junk food is turning your thighs into well-marbled steaks.”
To determine whether consuming high-protein ultra-processed foods is beneficial, I delved into research and consulted an expert.
First, About That Study…
Interestingly, the Radiology study failed to differentiate between high-protein ultra-processed foods and other forms of ultra-processed items. Consequently, participants could have been consuming protein bars, but their diets might have also been rife with fatty snacks and refined carbohydrates. Additionally, the participants averaged around 60 years old, raising questions about the study’s applicability to the general population.
Dr. Stuart Phillips, a protein researcher and kinesiology professor at McMaster University, does not believe that all sources of ultra-processed protein are linked to increased muscle fat.
“The key message from studies like this is that poor overall diet quality corresponds with poorer muscle quality, not that all ultra-processed foods negatively impact muscle,” explains Phillips.
Nevertheless, the study prompts an important question: will a diet heavily reliant on processed foods affect your muscle-building outcomes?
Are You Still Making Gains if Most of Your Protein Is Ultra-Processed?
According to Phillips, muscle growth primarily hinges on total protein intake and the amino acid composition.
“As long as the protein quantity, amino acid composition, and overall daily intake are sufficient, the degree of processing is generally insignificant to muscle protein synthesis and overall results,” he states. “A whey isolate is not a Twinkie, even if both are categorized similarly by NOVA.”
(Phillips refers to the NOVA classification system, which categorizes foods based on their processing level. Protein shakes, powders, and bars fall into this category.)
Essential amino acids, especially leucine, are vital for muscle protein synthesis, and the body doesn’t differentiate if that leucine is sourced from a whey supplement or a steak. When selecting a protein supplement or fortified food, choose those that provide leucine. If that information is not available, emphasize high-quality whole food protein sources, such as meat, dairy, soy products, lentils, and salmon.
Total protein intake across the day is equally important. Despite mixed messages, Phillips’ research indicates there is a threshold beyond which additional protein yields minimal benefits. For most healthy individuals, this threshold is approximately 1.6 grams of protein per kilogram of body weight per day.
However, there are exceptions. Younger individuals engaging in resistance training may find value in reaching that 1.6 grams per kilogram target, while adults over 65 might benefit from a range of 1.2 to 1.6 grams per kilogram. Individual goals, health status, and life stage significantly influence these recommendations.
“The 1.6 grams per kilogram figure should not be seen as an absolute limit,” Phillips adds. “It represents the point where the returns of extra protein for muscle growth begin to plateau. Older lifters and those who train intensively can reasonably approach 2.0 grams per kilogram without adverse effects, though the additional benefits might be hard to identify.”
The Bottom Line
As a dietitian, I advocate for sourcing the majority of your protein from whole foods. However, life’s circumstances sometimes make this challenging. In such instances, protein supplements like bars and powders can serve as practical alternatives.
It’s unnecessary to overanalyze your diet. What’s most important is the consistency and diversity of the foods you consume, including your protein sources.
Abby Langer, RD is the owner of Abby Langer Nutrition, a Toronto-based nutrition consulting and communications company
