Evolutionary Mismatch During the Menopausal Transition in Gen X Women: A Clinical Framework for Midlife Management

1. Introduction

Midlife women increasingly present with a mixture of problems that extend beyond the classical vasomotor symptoms of hot flushes and night sweats. These include persistent fatigue, weight gain, cognitive changes, reduced motivation and declining resilience [1,2,3,4]. Although these symptoms are commonly attributed to menopause or ageing, reproductive hormone decline alone does not fully account for their breadth or severity [5,6,7]. Despite normal or borderline pathology results, many women experience progressive deterioration in metabolic health, body composition and overall wellbeing that is difficult to explain within existing hormone-focused models [6,7,8,9]. Symptom- and/or hormone-based treatment approaches may provide partial relief but often fail to address the underlying drivers of this broader clinical presentation.

Generation X (Gen X) women, born between 1965 and 1980 (aged 46–61 years), represent the first cohort to reach midlife following lifelong exposure to modern lifestyle and environmental conditions [2],10–12). This is occurring alongside a rapidly escalating metabolic burden. In the United States, the prevalence of overweight and obesity in women aged 40–64 years has increased from approximately 49% in 1990 to over 74% in 2021, with projections suggesting more than 80% will be affected by 2050 [13]). Comparable patterns are evident in Australia, where approximately 80% of women in the Gen X cohort have an increased or substantially increased metabolic risk based on waist circumference [14]). These trends highlight the scale and urgency of metabolic dysfunction emerging during the midlife transition, reflecting disruption across interconnected metabolic, neuroendocrine and immune networks [15,16].

The midlife changes observed in many Gen X women can be better understood within the context of evolutionary mismatch, whereby human biology, adapted to conditions of intermittent food availability, high physical activity, stable circadian rhythms and intermittent stress, is increasingly discordant with the modern environment [7,17]. Contemporary lifestyles are characterised by continuous access to energy-dense foods, reduced physical activity, circadian disruption and sustained psychosocial demands, alongside increased exposure to environmental pollutants and endocrine-disrupting chemicals (EDC) [8,18]. These exposures, alongside industrialised dietary patterns, are associated with progressive reductions in gut microbiome diversity, further compounding metabolic and immune dysregulation [19,20]. The aim of the current review is to extend our evolutionary mismatch model by proposing a Gen X clinical phenotype and translating this model into an evolutionary realignment framework that can be implemented in clinical practice (Figure 1).

2. The Proposed Generation X Clinical Phenotype

Building on the evolutionary mismatch model described in our previous review [21]), the current paper considers how disruption of whole-body energy homeostasis may be expressed clinically in Gen X women. Homeostasis depends on coordinated signalling between central neuroendocrine networks and peripheral metabolic tissues to regulate appetite, substrate utilisation, energy expenditure, stress responses and anabolic function according to physiological demand [22,23]. Persistent insulin resistance (IR), inflammatory signalling, stress-axis activation and circadian disruption may reduce the flexibility and fidelity of these regulatory systems, impairing the capacity to maintain metabolic balance despite adequate energy availability [23,24,25]. Within an evolutionary framework, this may favour adaptive responses that conserve energy while increasing the drive to acquire it [26,27]. During the menopausal transition, fluctuating and declining ovarian hormone levels may further challenge this homeostatic capacity [28,29].

2.1. Adaptive Energy Conservation Under Perceived Scarcity

We propose that IR, chronic inflammation, stress-axis activation, circadian disruption and fluctuating ovarian hormones may together be interpreted centrally as reduced effective energy availability despite caloric abundance. Hypothalamic inflammation can induce central leptin and insulin resistance, blunting the cues which arcuate and ventromedial neurons use to gauge long-term energy sufficiency, while glucocorticoid excess further shifts regulatory set points towards energy conservation [22],23,30). Kisspeptin neurons are involved in coupling reproductive function to energy status and are suppressed by cortisol, inflammation and impaired leptin signalling. In addition, declining 17β-oestradiol (E2) may amplify this suppression during the menopausal transition [28],31,32). Reduced kisspeptin tone may in turn disinhibit arcuate agouti-related peptide/neuropeptide Y (AgRP/NPY) neurons, heightening hunger salience and weakening satiety [33,34]. In parallel, declining E2 alters dopaminergic tone within prefrontal and striatal pathways, which may reduce motivation for non-immediate goals while increasing responsiveness to palatable food cues [35,36].

Energy expenditure may be similarly downregulated. Altered hypothalamic–pituitary–thyroid dynamics and reduced tissue-level triiodothyronine (T3) action may lower thermogenesis and mitochondrial energy production. This ‘thyroid economy’ reflects a deliberate down-shifting of effective thyroid hormone action to reduce metabolic rate and conserve energy, and is a hallmark feature of adaptive thermogenesis [37,38]. Somatopause, with declining growth hormone (GH) and insulin-like growth factor-1 (IGF-1) signalling, further reduces anabolic capacity and lean mass, lowering resting energy expenditure and metabolic flexibility [39,40].

Together, these adaptations may result in a scarcity-adapted set point in which energy acquisition and conservation are co-activated despite caloric abundance. Adiposity and IR further impair hypothalamic signalling, and reduced lean mass lowers energy availability, creating a self-reinforcing cycle that may contribute to fatigue, weight-loss resistance and progressive metabolic decline. This model is proposed as one contributor to the Gen X phenotype rather than a complete explanation, and several of its components, particularly kisspeptin–AgRP interactions and thyroid economy, derive largely from experimental and caloric-restriction studies. Nonetheless, it provides a mechanistic basis for the clinical features described below.

2.2. Metabolic Dysregulation, Central Adiposity and Lean Mass Decline

A central feature of the proposed Gen X clinical phenotype is metabolic disturbance accompanied by visceral and ectopic fat deposition and central adiposity [41,42]. Visceral adipose tissue is metabolically active and strongly associated with IR, chronic inflammation and impaired metabolic flexibility [4,43], contributing to dysregulated glucose and lipid metabolism that may occur even when body mass index (BMI) is normal [44,45]. These changes frequently occur alongside progressive loss of lean muscle mass and function. Declining ovarian hormone levels, together with IR and chronic inflammation, may impair muscle protein synthesis and contribute to gradual loss of metabolically active tissue [40,46]. Because skeletal muscle is a major site of insulin-mediated glucose disposal, reductions in lean mass further compound IR, metabolic dysfunction and reduced physical capacity [18,47], reinforcing the adaptive cycle described in Section 2.1. Where increasing adiposity and declining muscle mass and function coexist, this pattern may progress towards sarcopenic obesity [48]). These changes can occur gradually and may be overlooked during midlife, yet they have important implications for long-term health, physical independence and quality of life [49]).

2.3. Neuroendocrine Symptom Cluster

In addition to measurable changes in body composition and metabolic function, many Gen X women experience a constellation of symptoms reflecting disruption of neuroendocrine and energy-regulation systems. This cluster commonly includes persistent fatigue, cognitive difficulties often described as “brain fog”, reduced concentration and focus and difficulty with memory retrieval, dysregulated appetite and cravings, and changes in mood and motivation [3,15].

These symptoms reflect the convergent effects of the neuroendocrine and metabolic disturbances described in our previous review [21]). Fatigue is associated with impaired mitochondrial function, reduced metabolic flexibility and disrupted circadian regulation; cognitive changes with altered cerebral energy metabolism and neuroinflammatory signalling; dysregulated appetite with disruption of hypothalamic energy sensing and reward pathways in the context of IR and modern food environments; and mood and motivational changes with altered neuromodulatory tone and stress-axis dysregulation [21]).

Cognitive symptoms warrant particular attention. Oestrogen supports cerebral glucose metabolism, mitochondrial bioenergetics and synaptic function, and neuroimaging studies have demonstrated reduced cerebral glucose metabolism across the menopausal transition, alongside changes in brain E2-receptor density that are associated with memory performance and menopausal symptoms [50,51]. These changes may contribute to the memory retrieval difficulties reported most frequently during perimenopause [52]). Although such symptoms are often transient, declining E2 signalling may also mark a window of vulnerability for later cognitive decline, particularly where metabolic dysfunction persists [50,53].

Collectively, these symptoms are best understood as clinical expressions of integrated system-level dysfunction rather than isolated hormonal effects, reflecting the cumulative impact of evolutionary mismatch across metabolic, neuroendocrine and behavioural domains.

2.4. Increased Long-Term Chronic Disease Risk

These metabolic, endocrine, and neurophysiological changes may have important implications for long-term health. The convergence of central adiposity, IR, declining muscle mass and neuroendocrine dysregulation during midlife may create an environment that increases susceptibility to several chronic diseases later in life. These include type 2 diabetes mellitus (T2DM) [54]), metabolic dysfunction associated steatotic liver disease (MASLD) [55]), cardiovascular disease (CVD) [56]), osteoporosis [57]) and dementia [50,53].

Women demonstrate a well-established longevity advantage relative to men across most contemporary human populations, a pattern attributed to interacting biological, behavioural and reproductive factors [58,59]. However, the convergence of metabolic, endocrine and environmental pressures described in this review raises the possibility that the health trajectories of Gen X women may be increasingly shaped by conditions that were largely absent during earlier periods of human evolutionary history. Whether these interacting influences may alter the long-standing female longevity advantage in future generations remains an important area for further investigation.

3. Evolutionary Realignment Framework

The mechanisms described in preceding sections indicate that evolutionary mismatch influences metabolic, endocrine and neurological health through disruption of core regulatory systems, including circadian rhythms, energy metabolism, stress physiology and gut microbiome composition [20]). Because the adaptive cycle described in Section 2.1 is sustained across regulatory networks, interventions targeting isolated pathways or symptoms are unlikely to be effective. Translating the proposed phenotype into clinical practice therefore requires interventions that target upstream regulatory processes. The proposed evolutionary realignment framework comprises eight intervention domains addressing circadian regulation, metabolic flexibility, stress physiology, environmental exposures, cerebral and mitochondrial function, musculoskeletal health, gut–hormone signalling and, where clinically appropriate, ovarian hormone signalling through menopausal hormone therapy (MHT), as summarised in Table 1.

Although these domains are relevant to midlife women generally, the Gen X cohort framing shapes clinical priorities within the described intervention domain. Many Gen X women entered the workforce before childcare and paid parental leave were widely available and have spent much of their adult lives combining paid employment with substantial household and caregiving responsibilities, including care of children and, increasingly in midlife, ageing parents [21],60,61). This cumulative role strain positions allostatic load and stress regulation as a central rather than adjunctive treatment target. Similarly, lifelong exposure to industrialised food environments, artificial light and EDCs, means that dietary pattern, circadian behaviour and exposure history warrant systematic assessment [12],20,21). The framework therefore emphasises identifying the mismatch exposures that have been most sustained for each woman, and prioritising the corresponding domains, rather than applying all interventions uniformly.

3.1. Circadian Realignment and Chrononutrition

The menopausal transition may increase vulnerability to circadian dysregulation, with declining ovarian hormones associated with reduced circadian alignment, altered sleep–wake regulation and changes in peripheral clock function [62,63,64]. Menopause-related sleep changes are associated with increased cardiometabolic risk, while circadian rhythmicity has been proposed as a potential biomarker of healthy ageing in women [65,66].

Circadian synchronisation is therefore a foundational strategy for addressing midlife metabolic and neuroendocrine dysfunction. Circadian rhythms regulate glucose metabolism, hormonal signalling, sleep architecture and energy balance, and are strongly influenced by meal timing [67,68]. Sleep, feeding and activity evolved as coordinated systems entrained by natural light–dark cycles, physical activity and food availability [69,70]. Modern exposure to artificial light and evening screen use, delayed sleep, prolonged sedentary periods, extended eating windows and late-night food intake can create temporal mismatch between behaviour and endogenous circadian physiology [71,72,73].

Chrononutrition concerns food intake timing relative to endogenous circadian rhythms, typically favouring earlier daytime energy consumption [67,74]. Meal timing reflects an evolutionarily conserved feeding–fasting cycle and provides a temporal signal for gastrointestinal physiology and gut microbial rhythms [74,75,76]. Metabolic responses to food vary across the biological day, with glucose tolerance and insulin sensitivity generally more favourable during the early active phase [77,78]. Later eating and circadian misalignment are associated with impaired glucose regulation and adverse metabolic outcomes [77,78]. Sleep and circadian disruption may also alter gut microbial composition, with reductions in Faecalibacterium and Lactobacillus and increases in Clostridium reported across some studies, with potential implications for inflammation and metabolic health [79]). Insufficient sleep may further increase energy intake and alter appetite and reward-related responses [80]).

A systematic review of 41 randomised controlled trials (RCTs) found that time-restricted eating (TRE) reduced body weight, BMI, fat mass, waist circumference, systolic blood pressure, fasting glucose, fasting insulin and triglycerides compared with usual diets [81]). Early TRE (eTRE) was superior to late TRE for body weight, waist circumference and fasting insulin. By confining intake to an earlier daytime window, eTRE may better align feeding with circadian metabolic rhythms while extending periods of lower insulin exposure and greater reliance on stored energy substrates, potentially supporting insulin sensitivity and glycaemic regulation [81,82].

Evidence in women is also emerging. Peters et al. reported improved sleep efficiency and reduced sleep fragmentation during eTRE in 31 women, 26 of whom were postmenopausal[83]). Jóźwiak et al. found that 16:8 TRE combined with exercise reduced psychological and somatic menopausal symptoms and improved physical and psychosocial quality-of-life measures more than exercise alone [84]). These findings support TRE and earlier, circadian-aligned eating as potentially useful strategies during the menopausal transition, although longer-term trials specifically examining eTRE in peri- and postmenopausal women are needed.

Circadian alignment can also be supported through regular sleep–wake timing, early natural light exposure, daytime physical activity and reduced evening exposure to bright and blue-enriched light [85]). Greater sleep regularity has been associated with lower mortality risk and may predict mortality more strongly than sleep duration [86]). Sleep hygiene practices may be particularly relevant during the menopausal transition, when vasomotor symptoms and changing ovarian hormone levels can further disrupt sleep continuity and circadian rhythmicity [66]).

3.2. Fuel Utilisation and Metabolic Flexibility

Metabolic flexibility describes the capacity to shift appropriately between glucose and fatty-acid oxidation according to nutrient availability and physiological demand [87,88]. A recent review identified perimenopause as a period of metabolic vulnerability characterised by reduced fat oxidation and impaired metabolic flexibility [89]). Declining E2 may also contribute to increasing visceral adiposity and altered lipid metabolism [30,41], while higher follicle-stimulating hormone (FSH) has been associated with lower postprandial fat oxidation [90]). In metabolically inflexible states, increased free fatty-acid availability coupled with reduced oxidative capacity can promote ectopic lipid accumulation, including hepatic steatosis, further impairing insulin signalling and mitochondrial function [88,91]. Insulin resistance further impairs fuel switching by reducing insulin-mediated glucose uptake into insulin-sensitive tissues, while increasing adipose lipolysis and free fatty-acid delivery to the liver, disrupting normal transitions between glucose and fat oxidation [30,88].

Dietary strategies should therefore target insulin sensitivity and glycaemic regulation while supporting appropriate substrate utilisation. Priorities include minimally processed, fibre-rich foods, adequate protein, high-quality complex carbohydrates in place of refined carbohydrates, and limiting excessive saturated-fat intake [87,92]. Mediterranean-style dietary patterns have been associated with lower indices of hepatic steatosis in women with overweight and obesity and improved body composition and cardiometabolic outcomes in midlife women [93,94]. A recent review further identified polyphenol-rich dietary patterns as a promising strategy for mitigating menopause-associated cardiometabolic risk through effects on glucose and lipid metabolism, blood pressure, inflammation and gut microbiota [95]).

Consistent meal structure and avoidance of routine breakfast skipping may further support insulin sensitivity and glycaemic regulation [96,97]. Exercise provides an important complementary stimulus for improving insulin sensitivity, mitochondrial function and substrate utilisation and is addressed further in Section 3.6. Despite increasing evidence for these individual approaches, direct dietary intervention studies measuring changes in metabolic flexibility across the menopausal transition remain limited, representing an important area for further research.

3.3. Allostatic Load and Stress Regulation

Allostatic load reflects the cumulative physiological burden generated by repeated or prolonged adaptation to stress across neuroendocrine, autonomic, immune, inflammatory and metabolic systems. During the menopausal transition, stress regulation may be challenged by interacting hormonal and behavioural changes, including fluctuating ovarian hormone levels and sleep disturbance, while age-related declines in dehydroepiandrosterone sulphate (DHEAS) may further reduce stress-adaptive capacity [3,98]. Importantly, menopause-associated sleep fragmentation can disrupt cortisol dynamics independently of E2 decline, identifying sleep as a modifiable contributor to hypothalamic-pituitary-adrenal (HPA)-axis dysregulation [99]). Chronic stress and altered HPA-axis feedback have also been associated with epigenetic changes in stress- and immune-related pathways that may promote inflammatory signalling and contribute to cumulative allostatic burden [100]). In Gen X women, occupational demands, caregiving responsibilities, role strain and persistent time pressure may further compound this physiological load [60,61].

Lifestyle and behavioural interventions should therefore prioritise reduction of modifiable stressors and restoration of adaptive capacity through psychological support, setting behavioural boundaries, adequate recovery, social connection, physical activity and sleep optimisation [101,102,103]. Menopause-specific studies provide support for the use of mindfulness-based interventions in clinical practice. A meta-analysis of 13 studies involving 1,138 women found a significant reduction in perceived stress (SMD −0.84, 95% CI −1.64 to −0.05), although effects on anxiety and depression were less consistent [104]). More recent evidence similarly supports the use of mindfulness, cognitive behavioural therapy and other mind-body interventions for stress, sleep and psychological symptoms during menopause [102,103].

Complementary therapies may also be considered within an individualised integrative approach, including selected herbal medicines and nutritional interventions according to symptom presentation, patient preference and clinical context [102,103]. For example, Withania somnifera has demonstrated menopause-specific benefits, with a recent RCT reporting improvements in perceived stress, menopausal symptoms and quality of life over eight weeks, alongside modest increases in E2 and progesterone and reductions in FSH and luteinising hormone, relative to placebo [105]). Overall, complementary therapies appear generally safe, with few serious adverse events reported, although further high-quality research is required [103]). These approaches should complement, rather than substitute for, addressing upstream psychosocial and lifestyle drivers of chronic stress.

3.4. Exposome and Environmental Load Reduction

The exposome encompasses cumulative environmental exposures across the life course and how these interact with an individual’s biological susceptibility. Environmental chemicals relevant to midlife women include compounds such as phthalates, bisphenols and parabens, alongside persistent pollutants such as perfluoroalkyl and polyfluoroalkyl substances, organochlorines, some heavy metals and air pollution [106]). Recent menopause-specific reviews associate these exposures with metabolic dysfunction and a range of menopausal symptoms, including adiposity, sleep disturbance, vasomotor symptoms, and cognitive and psychological symptoms [107,108]. Emerging evidence further suggests that the menopausal transition may represent a period of increased vulnerability to the effects of these exposures [108]). For Gen X women, this life-course perspective directs attention to both cumulative and ongoing exposure, particularly to persistent compounds that may bioaccumulate and remain in the body for prolonged periods.

Clinical management should emphasise pragmatic reduction of avoidable exposure rather than complete avoidance. A structured environmental assessment can identify major sources from food and food packaging, plastics, fragranced personal and household products, indoor dust and air, water and occupational exposures. Once identified, targeted individualised advice and practical recommendations can be made [106,109]. Preliminary intervention studies indicate that dietary modification and substitution of household and personal products can reduce measured concentrations of several EDC, although evidence related to menopausal health outcomes has yet to be established [109]). Personalised exposure assessment may further improve environmental-health literacy and behavioural change, with reductions in urinary phthalate exposure demonstrated following targeted recommendations [110]).

3.5. Cerebral Bioenergetics and Neuroprotection

The menopausal transition is increasingly recognised as a period of neuroendocrine and metabolic adaptation within the female brain. Neuroimaging studies have demonstrated menopause-related alterations in cerebral glucose metabolism, brain structure and E2-receptor density, supporting the importance of preserving neurological function across midlife [50,51].

Clinical strategies should therefore prioritise preservation of cerebral metabolic and vascular function while reducing factors that contribute to neuroinflammation and cognitive vulnerability. The circadian, metabolic and stress-regulation strategies outlined above may contribute synergistically through improved sleep, insulin sensitivity, vascular health and mitochondrial function. Dietary patterns emphasising minimally processed plant foods and a diversity of polyphenol-rich foods may provide additional neuroprotective support [95],111,112).

Specific polyphenol- and phytoestrogen-rich compounds may provide additional benefits. In postmenopausal women, long-term resveratrol supplementation improved cognition and cerebrovascular responsiveness alongside improvements in insulin sensitivity [113]). Cocoa and other flavanol-rich foods have also demonstrated favourable effects on selected cognitive outcomes [114,115]. Phytoestrogens, including soy isoflavones, are of particular interest during the menopausal transition, with preclinical evidence suggesting potential neuroprotective effects through E2 receptor signalling, antioxidant pathways, synaptic plasticity and mitochondrial energy metabolism [116,117]. Many phytoestrogens, including genistein and daidzein, exhibit preferential affinity for E2 receptor beta (ERβ), which is highly expressed in brain regions involved in memory and cognition. ERβ signalling has been implicated in synaptic plasticity, neurogenesis, mitochondrial function and neuroprotection, providing a plausible mechanistic basis for tissue-selective neurocognitive effects [118,119]. A meta-analysis of RCTs suggests modest benefits of soy isoflavones for overall cognition and memory, although effects were not evident across all cognitive domains [120]). Individual responses may also be influenced by differences in phytoestrogen metabolism and gut microbial conversion to bioactive metabolites [116]).

3.6. Musculoskeletal and Mitochondrial Function

Mitochondrial function is central to cellular energy production, metabolic flexibility and physiological resilience and may become increasingly vulnerable across the menopausal transition through the interacting effects of ageing, declining ovarian hormones , IR , inflammation and oxidative stress [121,122]. E2 influences mitochondrial biogenesis, respiration and redox regulation across multiple tissues, while human postmenopausal data suggest alterations in skeletal-muscle mitochondrial content and respiratory capacity [123,124]. Maintaining mitochondrial capacity therefore represents a broader therapeutic target than preservation of skeletal muscle alone.

Exercise is a potent stimulus for musculoskeletal and mitochondrial adaptation. Progressive resistance training supports muscle mass and strength while stimulating mitochondrial biogenesis and respiratory adaptation, with aerobic activity providing complementary benefits for oxidative capacity and mitochondrial turnover [125,126]. Individualised programmes incorporating resistance training two to three times weekly, regular aerobic activity and, where appropriate, weight-bearing or impact exercise can support muscle, mitochondrial and bone health [127,128].

Adequate energy, protein and micronutrient availability supports ATP production, training adaptation and musculoskeletal maintenance. Protein intakes of approximately 1.0–1.2 g/kg/day are commonly recommended for healthy older adults, although menopause-specific intervention evidence remains limited [129]), with protein distributed across the day and obtained from diverse high-quality sources, including plant and/or animal proteins. In a prospective study of 38,283 women followed across the menopausal transition, dietary patterns rich in legumes, nuts, fruits, vegetables and whole grains were associated with less weight gain and lower obesity risk, with the plant-forward Planetary Health Diet showing the strongest inverse association with weight gain [130]).

Adequate calcium, vitamin D and magnesium are also important for bone, muscle and cellular energy metabolism [131,132], while polyphenol-rich foods may support mitochondrial quality control through biogenesis, autophagy and redox regulation pathways [133,134]. Phytoestrogens may also support skeletal health, with recent evidence indicating modest improvements in lumbar spine, femoral neck and total-hip bone mineral density in peri- and postmenopausal women [135]).

3.7. Gut–Hormone–Microbiome Integration

The gut microbiome represents an important interface between diet, metabolic regulation and hormone signalling during the menopausal transition. Menopause has been associated with alterations in microbial composition and function, with potential consequences for oestrogen metabolism, inflammation, intestinal barrier integrity and cardiometabolic health [136,137].

Two microbiome-mediated pathways are particularly relevant to systemic E2 physiology. The estrobolome includes specific microbial species with β-glucuronidase activity that deconjugate oestrogens within the intestine, facilitating enterohepatic reabsorption [138,139]. Separately, gut microbes metabolise dietary phytoestrogens into biologically active metabolites. For example, the soy isoflavone daidzein can be converted to equol, while plant lignans are metabolised to enterodiol and enterolactone [117,139]. These pathways provide a rationale for supporting microbiome function during the menopausal transition, as microbial activity may influence the availability of endogenous oestrogens and the generation of bioactive dietary phytoestrogen metabolites, potentially supporting oestrogen-responsive signalling as ovarian E2 declines [140]). As the capacity for these microbial transformations varies between individuals, differences in microbiome composition and function may contribute to variation in response to phytoestrogen-rich foods [139,141].

Dietary fibre provides an additional link between microbiome and metabolic health. Fermentation of microbiota-accessible carbohydrates produces short-chain fatty acids (SCFA), particularly butyrate, acetate and propionate, which contribute to intestinal barrier integrity, inflammatory regulation, appetite signalling and glucose and lipid metabolism [142]). SCFAs may also influence appetite regulation through modulation of enteroendocrine hormones, including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), vagal signalling and central appetite pathways [143,144,145]. The gut-brain axis integrates enteroendocrine, vagal, immune and central neural signals involved in homeostatic and hedonic regulation of eating behaviour [145]). Evidence from inflammatory gastrointestinal disorders further suggests that intestinal inflammation can alter enteroendocrine and gut-brain signalling, with downstream effects on appetite regulation [146]).

Clinically, emphasis on increasing the diversity of fibre-rich whole plant foods, including foods rich in polyphenols and phytoestrogens may support microbial diversity, intestinal barrier integrity and increase the production of beneficial microbial metabolites such as SCFAs [147,148,149]. Responses to fibre vary according to factors including baseline microbiome composition and habitual diet, supporting an individualised approach rather than a uniform prescription [150]). Fibre intake may therefore be increased gradually according to gastrointestinal tolerance, particularly in individuals with low habitual intake.

3.8. The Role of Menopausal Hormone Therapy

Lifestyle medicine offers a foundational evidence-based framework for menopausal care and forms the central focus of our proposed clinical management pathway [101]). These approaches are emerging as important factors in empowering women to embrace menopause, improve symptoms and optimise wellbeing during the menopausal transition and beyond [151]). Lifestyle and nutritional strategies may also influence several hormone-responsive pathways, including insulin sensitivity, adiposity-related sex-steroid bioavailability, circadian regulation and gut-mediated oestrogen metabolism, and remain relevant irrespective of whether MHT is used [101,140]. Nevertheless, MHT remains an important therapeutic option for menopausal symptom management and the prevention of menopause-associated bone loss and fracture and may contribute to reducing future cardiometabolic risk when initiated in appropriately selected women early in the menopausal transition. Where MHT is considered, treatment should be individualised according to symptom burden, age and timing since menopause, contraindications, comorbidities and patient preference [152]).

MHT is an effective intervention for vasomotor symptoms, sleep disturbance, and genitourinary syndrome of menopause, and its physiological relevance extends beyond symptom relief [153]). In the hypothalamus, fluctuating E2 destabilizes KNDy neuron activity, narrows the thermoneutral zone, amplifies sympathetic output and contributes to menopausal vasomotor symptoms [154,155]. MHT with body-identical transdermal E2 restores E2-receptor mediated modulation of these circuits and helps re-establish thermoregulatory stability [156]). At the cellular level, E2 enhances mitochondrial biogenesis, improves oxidative phosphorylation efficiency, and increases antioxidant capacity, thereby counteracting the midlife decline in ATP production and redox balance [157]). Loss of E2 also promotes microglial activation and nuclear factor kappa B (NFκB)–driven cytokine release, while impairing inflammasome regulation [158]). MHT attenuates these neuroinflammatory processes and supports synaptic resilience via PI3K–Akt and ERK signalling. Systemically, E2 maintains metabolic flexibility by facilitating insulin signalling, promoting GLUT4 mediated glucose uptake, supporting mitochondrial β-oxidation, and modulating AMPK–mTOR nutrient sensing pathways [159]).

Progesterone has broad physiologic and molecular actions that are sleep-promoting, anxiolytic, mood stabilising, anti-inflammatory and metabolically beneficial. Micronised progesterone and its metabolites (e.g., allopregnanolone) act through nuclear PR-A/PR-B transcriptional regulation, membrane-bound progesterone receptors, GABA-A neurosteroid modulation, anti-inflammatory NF-κB suppression, and metabolic signalling, including insulin mediated and endothelial nitric oxide pathways [160]). Clinically, micronised progesterone may also support sleep, with randomised trial evidence demonstrating improvements in selected objective and self-reported sleep outcomes, predominantly in postmenopausal women [161]).

In summary, these mechanistic effects position MHT as a physiological stabiliser during the menopausal transition, with benefits shaped by timing, formulation and individual cardiometabolic risk, within a broader framework of evidence-based lifestyle and nutritional management.

3.9. Applying the evolutionary realignment framework in clinical practice

Implementation of these strategies may benefit from multidisciplinary care models integrating clinical medicine, nutrition, lifestyle interventions, and psychosocial support [162]). Recognising midlife as a critical window for metabolic and neuroendocrine intervention may allow earlier identification of risk and more targeted prevention strategies [101]). At a health systems level, approaches that address lifestyle, environmental exposures, and behavioural factors may contribute to reducing the long-term burden of chronic disease and improving population-level metabolic health outcomes [163]).

In Gen X women, the proposed phenotype can be identified through a combination of routine clinical measures. Waist circumference provides a useful marker of visceral adiposity and cardiometabolic risk beyond BMI [164]); fasting insulin and glucose, surrogate markers of IR such as triglyceride/HDL ratio or HOMA-IR index, HbA1c, lipid profile and elevated liver enzymes may indicate IR, dyslipidaemia or hepatic steatosis; and grip strength can screen for declining muscle strength [165]). Validated instruments such as the Menopause Rating Scale can identify somatic, psychological and urogenital symptom burden [166]), while a structured history of sleep and meal timing, physical activity, psychosocial load and environmental exposures can identify the mismatch domains most relevant to each woman. The cognitive component may be assessed using the Everyday Memory Questionnaire–Revised, which has been evaluated in an Australian community sample of 417 women aged 40–60 years. The questionnaire retrieval subscale identified elevated memory retrieval difficulties during perimenopause and has been proposed as a measure of menopause-related ‘brain fog’ [52,167].

The evolutionary realignment framework is summarised in Figure 2. The proposed Gen X clinical phenotype is positioned centrally, surrounded by the eight intervention domains, each paired with the evolutionary mismatch factor it addresses, with MHT included where clinically appropriate. Rather than operating as discrete treatments, the domains are intended to act together to re-establish the conditions under which human physiology evolved, including predictable light–dark cycles, intermittent energy intake, regular physical activity and adaptive rather than chronic stress, supporting a realigned trajectory for metabolic, neuroendocrine and long-term health.

3.10. Limitations

This narrative review has several limitations. It did not follow a systematic search strategy or formal quality appraisal, and evidence was selected to inform a conceptual framework rather than to estimate intervention effects. The proposed Gen X phenotype is derived from convergent mechanistic, observational and cohort evidence and has yet to be validated prospectively. Some of the intervention evidence comes from general or postmenopausal populations and draws predominantly on high-income Westernised settings. The combined effects of the domains have not been tested.

4. Conclusions

This review extends our evolutionary mismatch model by translating it into a clinically focused framework for Gen X women during the menopausal transition. We propose that the interaction between cumulative mismatch exposures, cohort-specific psychosocial pressures and decliningovarian hormone production may contribute to a recognisable clinical phenotype characterised by metabolic dysregulation, altered body composition, vasomotor symptoms and neuroendocrine features including fatigue, cognitive changes and dysregulated appetite.

Management should therefore extend beyond treatment of individual symptoms to consider the interacting physiological systems contributing to this presentation. The proposed evolutionary realignment framework integrates circadian, metabolic, nutritional, psychosocial, environmental, musculoskeletal, mitochondrial and gut–hormone strategies, together with MHT where clinically appropriate. It is not intended as a prescriptive protocol or to imply a uniform phenotype across all Gen X women, but as a practical and testable framework for individualised midlife care. Prospective studies are required to validate the proposed phenotype and determine whether interventions targeting the identified pathways improve clinical and long-term health outcomes in Gen X women.