Collagen has become a buzzword in the health, wellness, and beauty industries, touted for its potential benefits in skin health, joint function, and muscle recovery. But does scientific evidence support these claims?Collagen is the most abundant protein in the human body, accounting for about 30% of total protein content. It is a structural protein found in connective tissues, skin, tendons, bones, and cartilage, providing strength, elasticity, and resilience essential for maintaining structural integrity.The Digestible Indispensable Amino Acid Score (DIAAS) measures protein quality based on the digestibility of essential amino acids (EAA). Collagen’s amino acid profile differs significantly from high-quality proteins like whey. It is rich in glycine, proline, and hydroxyproline but deficient in EAA such as tryptophan, methionine, isoleucine, and threonine. As a result, collagen has a very low DIAAS—often near zero — because it cannot meet EAA requirements on its own.Although collagen peptides have shown benefits for muscle recovery when combined with resistance training, they are less effective compared to proteins with higher DIAAS. (Zdzieblik et al., 2015). Notably, the placebo in Zdzieblik's study was maltodextrin, which was neither isocaloric nor isonitrogenous, introducing potential confounding variables in the study.While studies suggest collagen supplementation may support skin health, joint health, and bone density, further research is needed to establish direct, causative benefits. Additionally, it was found that certain bioactive peptides derived from collagen exhibit antioxidant, anti-inflammatory, and antimicrobial properties.  There may be unexplored benefit in collagen but it does not qualify as a high-quality protein.Given collagen’s low DIAAS, it should not be relied upon as the sole protein source. However, it can complement high-quality proteins rich in EAA, creating a more balanced amino acid profile that supports overall health and protein synthesis.While DIAAS highlights collagen’s limitations as a standalone protein source, incorporating collagen into a diet alongside high-DIAAS proteins allows individuals to benefit from its unique properties without compromising overall protein quality. References1.Proksch, E., Schunck, M., Zague, V., Segger, D., Degwert, J., & Oesser, S. (2014). Oral intake of specific bioactive collagen peptides reduces skin wrinkles and increases dermal matrix synthesis. Skin Pharmacology and Physiology, 27(3), 113–119.2.FAO. (2013). Dietary protein quality evaluation in human nutrition: Report of an FAO Expert Consultation. FAO Food and Nutrition Paper 92.3.Mathai, J. K., Liu, Y., & Stein, H. H. (2017). Values for digestible indispensable amino acid scores (DIAAS) for some dairy and plant proteins may better describe protein quality than PDCAAS. British Journal of Nutrition, 117(4), 490–499.4.Zdzieblik, D., Oesser, S., Baumstark, M. W., Gollhofer, A., & König, D. (2015). Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: A randomized controlled trial. British Journal of Nutrition, 114(8), 1237–1245.5.Clark, K. L., Sebastianelli, W., Flechsenhar, K. R., Aukermann, D. F., Meza, F., Millard, R. L., ... & Albert, A. (2008). 24-week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain. Current Medical Research and Opinion, 24(5), 1485–1496.6.König, D., Oesser, S., Scharla, S., Zdzieblik, D., & Gollhofer, A. (2018). Specific collagen peptides improve bone mineral density and bone markers in postmenopausal women—A randomized controlled study. Nutrients, 10(1), 97.7.Bao, X., Liu, F., Ji, S., & Wang, X. (2019). Antioxidant and antimicrobial activities of bioactive peptides derived from marine collagen. Journal of Functional Foods, 57, 295–302. Editorial by Dr. Seiji AoyagiDr. Seiji is the Chief Scientific Officer of NiHTEK & the owner and partner of GPNi Japan. He brings over 35 years of experience in clinical and sports nutrition, with publications in both the U.S. and Japan. He holds 4 nutrition patents, led the approval of HMB in Japan, and founded Total Nutrition Therapy to train physicians in clinical nutrition.

 Soy protein, particularly in forms like soy protein isolate (SPI) and soy protein concentrate (SPC) is a prevalent ingredient in plant-based foods and supplements. Yet, multiple concerns have arisen regarding its production, nutritional value, digestive effects, allergenicity, hormonal impacts, and environmental footprint.Soy Protein Isolate (SPI) is produced by defatting soy flakes, commonly using hexane as the solvent followed by alkaline or acid extraction, isoelectric precipitation, and drying processes [1, 2]. Hexane, a volatile organic solvent, is widely used in oilseed processing but raises environmental and health concerns due to its flammability and neurotoxicity [3]. Notably, residual hexanal, a marker of lipid oxidation and possible solvent traces, has been identified in some commercial SPI products [4]. While manufacturers assert that hexane is fully removed during processing, peer-reviewed studies suggest trace residues may persist at low levels [5]. Digestive Effects and AntiNutrientsSoy naturally contains anti-nutritional factors such as phytic acid, trypsin inhibitors, and oligosaccharides, which can impair mineral absorption and cause digestive discomfort (e.g., gas, bloating, diarrhea), particularly in non-fermented forms like SPI [6, 7]. Phytic acid binds essential minerals like iron and zinc, reducing their bioavailability [8]. Trypsin inhibitors interfere with protein digestion, while raffinose and stachyose (types of oligosaccharides) are poorly digested in the small intestine, leading to fermentation in the colon [9]. However, germination (sprouting) of soybeans significantly reduces trypsin inhibitor activity and enhances digestibility, highlighting nutritional concerns with traditional SPI processing [10]. Allergic ReactionsSoy is a major food allergen, affecting approximately 0.3% of the general population, including both children and adults [11]. Allergic reactions can vary from mild symptoms such as hives and gastrointestinal discomfort to severe manifestations like anaphylaxis [12]. In infants, soy allergy may also present as Food Protein-Induced Enterocolitis Syndrome (FPIES), a delayed and potentially serious gastrointestinal response to soy protein [13]. Due to the widespread use of soy derivatives in processed foods, cosmetics, and pharmaceuticals, strict label scrutiny and avoidance are essential for affected individuals [14]. Hormonal Effects and Thyroid InteractionsSoy contains phytoestrogens, particularly isoflavones such as genistein and daidzein, which are structurally like human estrogen and can bind to estrogen receptors in the body [15]. While early animal studies raised concerns about potential hormonal disruption, comprehensive human clinical trials and meta-analyses have demonstrated no significant adverse effects on reproductive tissues, fertility, or male testosterone levels [16, 17]. Environmental and Ethical ImplicationsWhile soy is often promoted as a sustainable crop, its expansion, particularly in South America has been a major driver of deforestation, notably in the Amazon rainforest [18]. Although most soy is used for animal feed rather than human food, the growing global demand indirectly fuels land clearing for soy monocultures, contributing to biodiversity loss, carbon emissions, and disruption of indigenous lands [19]. Even when used in products like SPI, concerns remain around supply chain traceability, as raw soy inputs may originate from ecologically sensitive or illegally deforested zones [20, 21]. This underscores the importance of sourcing soy from deforestation-free certified suppliers and promoting regenerative agricultural practices.Considering the evidence, soy protein, particularly in its isolated and concentrated forms, presents a complex nutritional and ethical profile. While it remains a versatile and protein-rich option for many plant-based diets, concerns surrounding chemical residues from processing, anti-nutritional compounds, allergenicity, hormonal interactions, and environmental degradation cannot be overlooked. Advances in cleaner extraction methods, increased transparency in sourcing, and the adoption of regenerative agricultural practices are essential to mitigating these risks. As consumer demand continues to rise, striking a balance between health benefits, ecological stewardship, and food safety will be pivotal in shaping the future of soy-based nutrition. References1.Liu, K. (1997). Soybeans: Chemistry, Technology, and Utilization. Springer US.2.U.S. Food and Drug Administration (FDA). (2016). GRAS Notice for Soy Protein Isolate.3.OECD. (2001). Hexane CAS No: 110-54-3 SIDS Initial Assessment Report.4.Riaz, M. N. (2006). Soy Applications in Food. CRC Press.5.Centre for Science in the Public Interest (CSPI). (2009). Hexane: A Hidden Hazard in Processed Foods.6.Gilani, G. S., et al. (2005). Journal of AOAC International, 88(3), 967–987. 7.Friedman, M., & Brandon, D. L. (2001). Journal of Agricultural and Food Chemistry, 49(3), 1069–1086. 8.Hurrell, R. F. (2003). Journal of Nutrition, 133(9), 2973S–2977S. 9.Flatulence Factors in Legumes. (2006). In: Handbook of Nutraceuticals and Functional Foods, 2nd ed. 10.Vidal-Valverde, C., et al. (2002). Food Chemistry, 77(3), 327–336. 11.Savage, J., & Johns, C. B. (2015). Immunology and Allergy Clinics, 35(1), 45–59. 12.Sicherer, S. H., & Sampson, H. A. (2014). Journal of Allergy and Clinical Immunology, 133(2), 291–307.e5. 13.Nowak-Węgrzyn, A., et al. (2017). Journal of Allergy and Clinical Immunology: In Practice, 5(2), 370–378.e2. 14.Food and Drug Administration (FDA). (2022). Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA). 15.Setchell, K. D. R., & Cassidy, A. (1999). Journal of Nutrition, 129(3), 758S–767S. 16.Messina, M. (2010). Journal of Nutrition, 140(12), 2289S–2295S. 17.Hamilton-Reeves, J. M., et al. (2010). Fertility and Sterility, 94(3), 997–1007. 18.Gibbs, H. K., et al. (2015). Science, 347(6220), 377–378. 19.Henders, S., Persson, U. M., & Kastner, T. (2015). Environmental Research Letters, 10(12), 125012. 20.WWF. (2021). Soy and Deforestation. https://www.worldwildlife.org 21.Trase. (2020). The hidden deforestation risk in soy supply chains. Stockholm Environment Institute and Global Canopy.  Editorial by Dr. Seiji AoyagiDr. Seiji is the Chief Scientific Officer of NiHTEK & the owner and partner of GPNi Japan. He brings over 35 years of experience in clinical and sports nutrition, with publications in both the U.S. and Japan. He holds 4 nutrition patents, led the approval of HMB in Japan, and founded Total Nutrition Therapy to train physicians in clinical nutrition.

 The use of glucagon-like peptide-1 receptor agonists (GLP-1) has revolutionized the treatment of type 2 diabetes and obesity. Medications such as semaglutide, liraglutide, and dulaglutide offer dual benefits of glycemic control and weight loss through mechanisms that include enhanced insulin secretion, suppressed glucagon release, delayed gastric emptying, and reduced appetite [1]. However, while the pharmacologic efficacy of GLP-1 is well-established, optimal outcomes depend significantly on complementary lifestyle interventions, but most critically, nutritional management. Reduced Appetite and the Risk of Nutrient DeficiencyGLP-1 work in part by reducing appetite and promoting satiety, leading to significantly lower caloric intake. While this is beneficial for weight loss and metabolic improvement, it raises concerns about micronutrient and macronutrient sufficiency, especially over long period of time [2]. Patients may experience early satiety or aversion to certain food textures, reducing the overall diversity and volume of dietary intake.A nutrient-dense diet becomes crucial under these conditions. This means prioritizing foods (and supplements, where necessary) that provide essential vitamins, minerals, fiber, and bioavailable protein within a restricted calorie budget. Without careful dietary planning, patients risk developing deficiencies in iron, vitamin B12, calcium, magnesium, and fat-soluble vitamins [3]. Protein Intake and Muscle PreservationOne of the critical nutritional priorities during GLP-1 therapy is maintaining lean body mass. Although weight loss induced by GLP-1s is primarily from fat mass, studies indicate that 20~40% may come from lean tissue, particularly in older adults and those with insufficient protein intake [4].To mitigate this risk, adequate protein consumption is essential. The recommended intake for weight-stable adults (0.8 g/kg body weight/day) is likely insufficient for GLP-1 users undergoing caloric restriction. Instead, a higher intake, ranging from 1.2~1.6 g/kg body weight/day is advised to support muscle protein synthesis (MPS), especially when combined with resistance exercise [5]. Furthermore, protein quality matters: fast-digesting, leucine-rich proteins such as whey are particularly effectiv.Leucine, an essential branched-chain amino acid, serves as a key activator of the mTOR pathway, which regulates muscle anabolism. Intake of ~2.5 g of leucine per meal is recommended to maximally stimulate MPS in older adults [6]. For GLP-1 users consuming fewer meals, achieving this threshold at each eating occasion becomes even more important. Managing Gastrointestinal Side EffectsGastrointestinal (GI) symptoms are among the most common side effects of GLP-1, including nausea, bloating, reflux, constipation, and diarrhea. These symptoms can compromise adherence and nutritional intake, especially during the early phase of therapy [7].Dietary strategies to alleviate GI discomfort include:Frequent, small meals rather than large mealsLow-fat, low-fiber meals during nausea episodesAvoidance of FODMAP-rich foods that may exacerbate bloating or diarrhea [8]Hydration and soluble fiber to manage constipationFurthermore, protein supplements used in this context should be low in lactose, low in FODMAPs, and easily digestible. Hydrolyzed proteins or fermented plant-based proteins with proven tolerability may enhance compliance in sensitive individuals.Table 1. High-FODMAP and Low-FODMAP foods High-FODMAPLow-FODMAPFruitsapples, pears, cherries, watermelonstrawberries, oranges, grapes, bananas (in moderation)Vegetablesonions, garlic, cauliflower, asparaguscarrots, zucchini, spinach, bell peppersDairy milk, soft cheeses, yogurtlactose-free milk, almond milk, hard cheesesLegumeslentils, chickpeas, black beanscanned lentils (rinsed), firm tofu, peanutsGainswheat, rye, barleyrice, quinoa, oats, gluten-free breadSweetenerssorbitol, mannitol, xylitol (found in sugar-free gums and candies)table sugar, maple syrupMetabolic Adaptation and Long-Term Weight MaintenanceWeight loss through pharmacotherapy is only part of the equation. Long-term success depends on the ability to maintain reduced body weight and metabolic gains. Nutritional counseling plays a pivotal role in establishing sustainable eating habits, preventing muscle loss, and minimizing metabolic adaptation [9].GLP-1 therapy should be paired with a structured, personalized dietary plan that evolves with the patient’s changing physiology and appetite. High-protein, low-glycemic diets have been shown to reduce postprandial glucose excursions and improve satiety, making them particularly suitable for GLP-1 users [10]. Special Populations: Older Adults and Sarcopenia RiskOlder adults, already at risk of sarcopenia and frailty, require even more careful nutritional oversight during GLP-1 therapy. Age-related anabolic resistance makes it harder to preserve muscle mass during weight loss. For this group, higher protein intake (≥1.5 g/kg body weight/day), adequate vitamin D, and possibly targeted amino acid supplementation (e.g., leucine) should be considered [11].Moreover, older adults may also experience compounded appetite suppression and taste changes, further limiting dietary intake. Dietitians must ensure that meals are palatable, easy to prepare, and culturally appropriate while delivering essential nutrients. Integrating Nutritional Support into GLP-1 Clinical CareDespite the clear need for dietary management, many clinical settings do not routinely integrate dietitians or structured nutritional care into GLP-1 protocols. Given the complexity of appetite, behavior change, and potential nutrient gaps, multidisciplinary support should be the standard.A 2023 consensus from the American Association of Clinical Endocrinology emphasized that lifestyle counseling, including nutrition should accompany all obesity pharmacotherapies, not only to enhance outcomes but to mitigate risks [12].Digital nutrition platforms, meal delivery services tailored to GLP-1 users, or specialized protein products (e.g., high-leucine, low-FODMAP formulations) may offer scalable solutions to support adherence in real-world settings.GLP-1 receptor agonists offer powerful tools for managing obesity and type 2 diabetes, but their success hinges on more than pharmacology. Nutritional management is not optional, rather it is foundational to maximizing benefits, minimizing adverse effects, and sustaining long-term health. Optimizing protein intake, ensuring micronutrient adequacy, addressing GI side effects, and tailoring interventions to individual needs are essential components of care. As the use of GLP-1 therapy expands, so too must our commitment to comprehensive, evidence-based nutritional support. References1.Drucker, D. J. (2018). Cell Metabolism, 27(4), 740–756.2.Hess, D. A., et al. (2022). Current Obesity Reports, 11(1), 1–10.3.Mechanick, J. I., et al. (2020). Obesity (Silver Spring), 28(S1), S1–S58.4.Rasmussen, T. S., et al. (2023). Diabetes, Obesity and Metabolism, 25(2), 471–480.5.Phillips, S. M., & Moore, D. R. (2021). Nutrients, 13(6), 1921.6.Devries, M. C., & Phillips, S. M. (2015). Journal of Food Science, 80(S1), A8–A15.7.Nauck, M. A., & Meier, J. J. (2019). European Journal of Endocrinology, 181(6), R211–R234.8.Staudacher, H. M., & Whelan, K. (2017). Gastroenterology and Hepatology, 14(4), 230–237.9.Hall, K. D., & Kahan, S. (2018). Medical Clinics of North America, 102(1), 183–197.10.Astrup, A., et al. (2020). The Lancet Diabetes & Endocrinology, 8(7), 595–605.11.Bauer, J., et al. (2013). Journal of the American Medical Directors Association, 14(8), 542–559.American Association of Clinical Endocrinology (AACE). (2023). AACE clinical practice guideline for comprehensive obesity care. https://pro.aace.com/obesity-guideline Editorial by Dr. Seiji AoyagiDr. Seiji is the Chief Scientific Officer of NiHTEK & the owner and partner of GPNi Japan. He brings over 35 years of experience in clinical and sports nutrition, with publications in both the U.S. and Japan. He holds 4 nutrition patents, led the approval of HMB in Japan, and founded Total Nutrition Therapy to train physicians in clinical nutrition.

 I just celebrated my 62nd birthday, so I thought it would be appropriate to address the importance of protein intake for my generation. Protein consumption is crucial for elderly individuals, particularly those experiencing anabolic resistance—a condition where the body’s ability to synthesize proteins diminishes with age. This resistance can lead to muscle loss, decreased strength, and increased frailty, significantly impacting overall health and quality of life.Muscle maintenance and growth are key concerns for the elderly, and adequate protein consumption helps counteract muscle loss associated with aging. Protein supports muscle protein synthesis, which is essential for maintaining physical strength and functionality. Nonetheless, inadequate protein intake and anabolic resistance can lead to a condition known as sarcopenia.Sarcopenia, the age-related loss of muscle mass and strength, can be mitigated through proper protein intake. Regular consumption of high-quality protein sources can slow down or even reverse this condition. High-quality protein refers to those with higher DIAAS (Digestible Indispensable Amino Acid Score).In addition, protein plays a critical role in healing and recovery for elderly individuals recovering from illness or surgery. It supports tissue repair and immune function, helping to reduce recovery time.Protein is not just important for muscle health—it also contributes significantly to bone health. Protein makes up about 30–40% of bone’s dry weight and supports the matrix structure of bones. Adequate protein intake can help reduce the risk of fractures and osteoporosis, which are significant concerns for the elderly.Conversely, obesity and diabetes are also prevalent health concerns for sedentary elderly individuals. Protein is more satiating than carbohydrates or fats, which can help maintain a healthy weight. This is particularly important as obesity can exacerbate health issues in older adults. Higher-protein diets can positively influence metabolic health by helping regulate blood sugar levels and reducing the risk of type II diabetes, which is more prevalent in aging populations.So, can the elderly overcome anabolic resistance? There are many ways elderly individuals can overcome anabolic resistance. Older adults should aim for a higher protein intake than the general recommendations, ideally around 1g/kg of body weight per day.Incorporating a variety of protein sources—including lean meats, dairy, legumes, and plant-based proteins—can help meet these nutritional needs.Not only does the quantity and quality of protein matter, but the timing of consumption is equally important. Distributing protein intake throughout the day, especially by consuming protein-rich meals and snacks, can enhance muscle protein synthesis5 and counteract the effects of anabolic resistance.Additionally, engaging in regular resistance training or weight-bearing exercises can stimulate muscle protein synthesis and improve the body's response to protein intake.Ensuring adequate protein intake is essential for elderly individuals, particularly those facing anabolic resistance. By promoting muscle health, enhancing recovery, and supporting overall well-being, proper protein consumption can significantly improve the quality of life for the aging population. In addition, regular resistance training or weight-bearing exercises should be added. As the saying goes, "No pain, no gain."References1. Cruz-Jentoft, A. J., & Sayer, A. A. (2019) Sarcopenia: Revised European consensus on definition and diagnosis. Age and Ageing, 48(1), 16-31.2. Bauer, J. M., et al. (2013) Evidence-based recommendations for optimal dietary protein intake in older people: a position paper of the PROT-AGE Study Group. Journal of Nutrition, Health & Aging, 17(7), 635-648.3. Volpi, E., et al. (2013) Aging and the muscle protein synthetic response to meal ingestion. Current Opinion in Clinical Nutrition and Metabolic Care, 16(1), 83-88. 4. Paddon-Jones, D., et al. (2008) Protein and healthy aging. American Journal of Clinical Nutrition, 87(5), 1552S-1556S. 5. Kumar, V., et al. (2009) Aging disrupts the muscle protein synthetic response to resistance exercise. Journal of Clinical Endocrinology & Metabolism, 94(3), 976-983. 6. Cameron, J. D., et al. (2014) The role of dietary protein in the prevention and management of sarcopenia. Nutrition Reviews, 72(5), 308-316.  Editorial by Dr. Seiji AoyagiDr. Seiji is the Chief Scientific Officer of NiHTEK & the owner and partner of GPNi Japan. He brings over 35 years of experience in clinical and sports nutrition, with publications in both the U.S. and Japan. He holds 4 nutrition patents, led the approval of HMB in Japan, and founded Total Nutrition Therapy to train physicians in clinical nutrition.

 Protein intake, physical exercise, and testosterone are interdependent factors that play critical roles in skeletal muscle anabolism, metabolic health, and overall physical performance. Testosterone regulates protein metabolism, while exercise modulates hormonal responses and influences protein requirements. This article synthesizes current evidence regarding the interactions among protein intake, exercise type and intensity, and testosterone levels, highlighting implications for athletic performance and health optimization. Testosterone is a key androgenic-anabolic hormone that contributes to muscle hypertrophy, bone density maintenance, and metabolic regulation.Physical exercise, particularly resistance training, is known to acutely elevate testosterone concentrations, while chronic training adaptations influence baseline levels. Acute increases in circulating testosterone occur following high-volume, moderate-to-high intensity resistance exercises (70–85% 1RM) with rest periods of 60–90 seconds. Chronic resistance training supports maintenance or modest elevation of basal testosterone, particularly in younger and middle-aged individuals.On the other hand, moderate aerobic exercise is generally beneficial for endocrine health, but excessive endurance training, particularly when coupled with energy deficits may suppress testosterone via hypothalamic-pituitary-gonadal (HPG) axis down regulation.Testosterone exerts its effects primarily by stimulating muscle protein synthesis (MPS), a process requiring adequate amino acid availability. Dietary protein serves as the primary substrate for MPS and is a critical nutritional factor in supporting testosterone-mediated adaptations. However, imbalances in macronutrient intake, overtraining, or chronic caloric restriction may disrupt this relationship.Testosterone modulates muscle tissue through activation of the androgen receptor, enhancing transcription of contractile proteins. It also influences satellite cell activation, supporting muscle repair and growth. Protein ingestion stimulates MPS through activation of the mTOR pathway, and testosterone enhances this process synergistically.Meta-analyses indicate that daily protein intakes of 1.6–2.2 g/kg body weight are optimal for maximizing muscle hypertrophy during resistance training.Although protein is essential for muscle building, extremely high-protein diets (>3.4 g/kg/day) do not yield further testosterone benefits and may reduce dietary fat intake below levels necessary for steroid hormone synthesis. Adequate fat intake (≥25–30% of total energy) supports testosterone production through cholesterol availability.Whey, casein, and high-quality plant proteins provide complete amino acid profiles are recommended. Whey protein has been associated with reduced post-exercise cortisol levels, potentially preserving testosterone activity in the recovery phase.The anabolic effects of testosterone are amplified when resistance training is paired with sufficient protein intake. Conversely, inadequate protein consumption during high-intensity training may impair MPS despite elevated testosterone. Chronic caloric deficits, especially when combined with high training loads, can suppress testosterone irrespective of protein adequacy.So, the practical recommendations to naturally increase testosterone are.Resistance Training: Incorporate multi-joint, moderate-to-high intensity exercises with moderate rest intervals to optimize acute testosterone responses.Protein Distribution: Spread protein intake evenly (3–5 feedings/day) to sustain MPS throughout the day.Fat Intake Preservation: Maintain dietary fats at ≥25% of total energy to support steroidogenesis.Recovery Management: Ensure adequate sleep (7–9 h/night) and avoid chronic overreaching to prevent endocrine disruption.Testosterone, exercise, and protein intake form a tightly linked triad influencing muscle growth, recovery, and overall metabolic health. Resistance training and adequate protein intake work synergistically to maximize testosterone’s anabolic effects, whereas chronic caloric restriction, low dietary fat intake, or overtraining can impair this relationship. A balanced approach to macronutrient intake, training load, and recovery is essential for optimizing endocrine function and performance. References1.Kadi, F. (2008). Aging Male, 11(4), 175–181.2.Kraemer, W. J., et al. (1990). Journal of Applied Physiology, 69(5), 179–186.3.Bhasin, S., et al. (1996). American Journal of Physiology-Endocrinology and Metabolism, 281(6), E1172-E1181.4.Morton, R. W., et al. (2018). British Journal of Sports Medicine, 52(6), 376–384.5.Hackney, A. C. (2020). Journal of Endocrinological Investigation, 43, 1341–1348.6.Volek, J. S., et al. (1997). Journal of Applied Physiology, 82(1), 49–54.7.Wang, Y., et al. (2018). Clinical Endocrinology, 88(5), 743–751.8.Antonio, J., et al. (2001). Nutrition, 17(5), 397–400.9.Friedl, K. E., et al. (2000). Journal of Applied Physiology, 88(5), 1820–1830.  Editorial by Dr. Seiji AoyagiDr. Seiji is the Chief Scientific Officer of NiHTEK & the owner and partner of GPNi Japan. He brings over 35 years of experience in clinical and sports nutrition, with publications in both the U.S. and Japan. He holds 4 nutrition patents, led the approval of HMB in Japan, and founded Total Nutrition Therapy to train physicians in clinical nutrition.