The gap between best-case and typical-case evidence
The strongest evidence for high-protein diets comes from studies on older adults or people with chronic disease who need more protein to overcome 'anabolic resistance' — a condition where muscles don't respond normally to protein [3]. But for healthy, inactive people, the same review found that protein supplements without resistance training produce only marginal effects on strength and performance [3]. This means the dramatic muscle-building claims you see on social media apply mostly to people who are already exercising hard.
On the other hand, the largest and most rigorous study here — combining data from over 126,000 pregnancies — found that high protein intake (over 100g/day) was linked to a modest 10% increased risk of preterm delivery, though no increase in low birth weight or infant death [1]. This is a far cry from the 'safe for everyone' message often promoted. The same study also found that very low protein intake (under 60g/day) was linked to a 59% higher risk of low birth weight, so balance matters [1].
The processed food problem: easy to overdo it
Many people get their extra protein from high-protein processed foods (HPPFs) like bars, shakes, and fortified breads. A 2024 study of 36 such products found that a single serving plus a typical portion of meat could provide between 66% and 306% of the recommended daily protein intake — meaning it's very easy to overshoot [2]. Half of the 139 survey respondents said they consumed these products without any control [2].
Even a well-intentioned product like high-protein gluten-free bread can be a double-edged sword. A 2025 study showed that adding high-protein rice flour to gluten-free bread boosted its nutritional value and consumer appeal, but the same study also noted that gluten-free products are often low in fiber and high in fat and carbs [4]. So a 'high-protein' label doesn't automatically make a food healthy.
About These Sources
This answer is built on 5 peer-reviewed studies — published from 2021 to 2026, 4 from 2024 or later, 3 in Q1 journals — selected as the most relevant from 5 studies that passed quality screening, drawn from 54 papers retrieved from a database of over 500 million.
Sources used in this answer
Old Question Revisited: Are High-Protein Diets Safe in Pregnancy?
In a combined analysis of over 126,000 pregnancies from two large birth cohorts, high protein intake (>100g/day) was weakly associated with a 10% increased risk of preterm delivery, but no increase in low birth weight or infant death; very low protein (<60g/day) was linked to a 59% higher risk of low birth weight.
High-Protein Processed Foods: Impact on Diet, Nutritional Status, and Possible Effects on Health
A survey of 36 high-protein processed foods found that a single serving plus 150g of meat could provide 66-306% of the recommended daily protein intake, and half of 139 survey respondents consumed these products without any control.
High Protein Diets: What to Tell Our Patients.
A clinical review notes that for inactive people, protein supplements without resistance training produce only marginal gains in strength, and that muscle mass is better maintained by exercise alone; it also warns of toxin production from excess protein, especially in kidney disease.
Development of Gluten-Free Bread With High-Protein Rice Flour and Effects of Alpha-Amylase Enzyme on Bread Properties.
A study on gluten-free bread using high-protein rice flour found that adding alpha-amylase enzyme improved texture and consumer appeal, but the base gluten-free products are often low in fiber and high in fat and carbs.
High-Protein Diets: Characteristics of Bacterial Fermentation and Its Consequences on Intestinal Health
A review of gut fermentation found that high-protein diets can disrupt microbial balance, promote pathogenic bacteria, and increase harmful compounds like ammonia and biogenic amines, impairing gut barrier function and increasing inflammation.