Protein, mTORC1 and the Menopausal Metabolism: A Reappraisal of High-Leucine Approaches
- Lauren Dyer
- Jul 15
- 2 min read
Leucine plays a critical role in skeletal muscle anabolism via mTORC1 activation and is often highlighted as a key nutrient for preserving lean mass in peri- and postmenopausal women.
However, muscle-centric strategies that increase leucine intake through high-protein diets or BCAA supplementation require careful contextualisation.
In metabolically inflexible individuals - particularly those with sedentary lifestyles, high stress levels, or declining oestrogen, chronic mTORC1 stimulation may contribute to insulin resistance through multiple pathways.
Sustained activation of mTORC1 suppresses AMPK signalling, impairs autophagy, and disrupts insulin receptor function by promoting serine phosphorylation of IRS-1 (Lynch & Adams, 2014). This can lead to reduced glucose uptake in peripheral tissues and increased hepatic gluconeogenesis, driving a pattern of metabolic rigidity that favours fat storage over oxidation.
While leucine-induced protein synthesis is desirable in anabolic windows such as post-exercise recovery, constant stimulation in the absence of energy flux or mitochondrial turnover may contribute to metabolic dysfunction, particularly in hormonally compromised states.
In addition, leucine competes with tryptophan for transport across the blood–brain barrier via the LAT1 transporter. Diets disproportionately high in BCAAs - especially when combined with low carbohydrate intake can reduce central serotonin synthesis (Fernstrom, 2005).
In midlife women already vulnerable to low mood, sleep disruption, and oestrogen decline, this neurochemical imbalance may exacerbate symptoms often misattributed solely to hormonal changes.
Optimising protein intake remains important, but an overemphasis on leucine-rich strategies such as BCAA supplements, whey, and high intakes of isolated or meat-based proteins can oversimplify the broader metabolic and neuroendocrine demands of the menopausal transition. A more integrative approach that accounts for nutrient signalling, mitochondrial health, liver function, and amino acid balance is often necessary to support sustainable fat loss, energy, and cognitive stability in this context.
Lauren Dyer, BSc MSc DipCLN, IFM Certified Health Coach
Specialist in Women’s Health | Functional Nutrition & Personalised Assessment Plans
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