Retrospective analysis of the effects of high versus extra-high whey protein intake on muscle strength and nutritional status in adults aged 45–65 years

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Background: Age-related muscle decline often begins in middle age, affecting strength, functional performance and nutritional status. Protein supplementation supports muscle mass and strength, but comparative data on high versus extra-high protein intake in adults aged 45–65 years are limited. This study evaluated the effects of high (HP) and extra-high whey protein (XHP) supplementation on muscle strength, anthropometry and nutritional outcomes in this transitional age group. Methods: A retrospective analysis was conducted using medical records of participants who received HP or XHP supplementation for at least 60 days. Inclusion required complete documentation of demographic details, clinical history, anthropometrics, nutritional assessment (mini nutritional assessment short form (MNA-SF)) and handgrip strength. Extracted data included weight, BMI, waist and hip circumference, mid-upper arm and calf circumference and muscle strength at baseline and follow-ups over two months. Results: HP supplementation led to significant increases in weight and BMI (p<0.05), whereas XHP protein intake was associated with reductions in these parameters. between groups in waist and hip circumference, MUAC and calf circumference emerged from 30 days onward (p<0.05). Handgrip strength improved in both groups initially, but XHP supplementation produced superior functional gains 45 and 60 days (p<0.05). Conclusions: High-protein supplementation with whey protein provided dose-dependent benefits. Moderate intake supported anabolic recovery, while higher intake improved lean body mass and muscle strength. These findings highlight the therapeutic role of dietary protein in enhancing muscle quality, metabolic health and functional performance, helping prevent and manage sarcopenia and age-related muscle decline.