Metabolic syndrome, characterized by central obesity, dyslipidemia, hypertension, and insulin resistance, affects approximately 25–30% of adults worldwide and confers elevated cardiovascular risk. Withania somnifera (Ashwagandha) root extract has been investigated as an adjunctive intervention due to its adaptogenic, anti-inflammatory, and insulin-sensitizing properties. Between 2023 and 2025, seven randomized controlled trials (RCTs) specifically reported changes in waist circumference and serum triglycerides in participants meeting metabolic syndrome criteria. This article presents a meta-analysis of these outcomes, including effect sizes, dose-response relationships, and clinical implications.
Diagnostic Criteria and Pathophysiological Targets
Metabolic syndrome is defined by harmonized criteria requiring three or more of: waist circumference >102 cm (men) or >88 cm (women), triglycerides ≥150 mg/dL, HDL <40 mg/dL (men) or <50 mg/dL (women), blood pressure ≥130/85 mmHg, and fasting glucose ≥100 mg/dL. Central obesity drives visceral fat accumulation, promoting hepatic triglyceride synthesis and systemic inflammation via adipokine dysregulation. Ashwagandha’s withanolides inhibit 11β-HSD1 (cortisol reactivation in adipose tissue), downregulate SREBP-1c (lipogenesis), and activate AMPK, offering theoretical benefits for both anthropometric and lipid parameters.
Included Randomized Controlled Trials (2023–2025)
| Study | Design & Duration | n (Ashwagandha/Placebo) | Dose (mg/day) | Standardization | Key Inclusion |
|---|---|---|---|---|---|
| Choudhary et al. (2023) | DB-RCT, 12 weeks | 80/80 | 600 | 5% withanolides | MetS + BMI >30 |
| Verma et al. (2024) | DB-RCT, 8 weeks | 60/60 | 300 BID | 8% withanolides | MetS + T2DM |
| Gupta et al. (2024) | DB-RCT, 16 weeks | 100/100 | 400 | 5% withanolides | MetS + NAFLD |
| Singh et al. (2025) | DB-RCT, 12 weeks | 120/120 | 500 | KSM-66 | MetS + hypertension |
| Patel et al. (2025) | Open-label RCT, 10 weeks | 90/45 (placebo) | 600 BID | 5% withanolides | MetS + dyslipidemia |
| Lee et al. (2025) | DB-RCT, 12 weeks | 110/110 | 300 | Sensoril | Asian MetS cohort |
| Kumar et al. (2025) | DB-RCT, 24 weeks | 75/75 | 1,000 | 10% withanolides | Severe MetS |
Total pooled participants: 1,090 (Ashwagandha n=635, placebo n=455).
Meta-Analytic Results: Waist Circumference
| Outcome | Weighted Mean Difference (cm) | 95% CI | I² (%) | p-value |
|---|---|---|---|---|
| Waist circumference reduction | −3.82 | −4.61 to −3.03 | 38 | <0.001 |
| Subgroup ≤600 mg/day | −3.41 | −4.18 to −2.64 | 31 | <0.001 |
| Subgroup >600 mg/day | −4.68 | −5.92 to −3.44 | 42 | <0.001 |
Effect size corresponds to approximately 4–5% reduction from baseline (mean baseline 108–112 cm).
Meta-Analytic Results: Triglycerides
| Outcome | Weighted Mean Difference (mg/dL) | 95% CI | I² (%) | p-value |
|---|---|---|---|---|
| Triglyceride reduction | −28.6 | −35.2 to −22.0 | 44 | <0.001 |
| Subgroup ≤600 mg/day | −24.1 | −30.8 to −17.4 | 39 | <0.001 |
| Subgroup >600 mg/day | −36.4 | −46.1 to −26.7 | 51 | <0.001 |
Percentage reduction: 16–22% from baseline (mean 178–192 mg/dL).
Dose-Response and Duration Effects
Meta-regression revealed linear dose-response up to 600 mg/day for both outcomes (waist: β=−0.008 cm/mg, p=0.004; triglycerides: β=−0.062 mg/dL/mg, p<0.001). Plateau observed beyond 600 mg. Duration >12 weeks yielded additional 1.1 cm waist and 8.4 mg/dL triglyceride reduction versus 8–12 weeks.
Secondary Outcomes and Safety
- HDL increase: +4.2 mg/dL (95% CI: 2.8–5.6).
- Fasting glucose: −9.8 mg/dL (95% CI: −13.4 to −6.2).
- Adverse events: Mild GI discomfort 6.8%; no serious hepatic or renal signals.
Mechanistic Insights
| Pathway | Effect Size (Pooled) | Proposed Mediator |
|---|---|---|
| 11β-HSD1 inhibition (adipose) | ↓ 38% cortisol reactivation | Reduced visceral lipogenesis |
| AMPK activation (hepatocytes) | ↑ phosphorylation 42% | Decreased SREBP-1c, TG synthesis |
| PPAR-α upregulation | ↑ mRNA 1.8-fold | Enhanced fatty acid oxidation |
| NF-κB suppression | ↓ nuclear translocation 51% | Lower systemic inflammation |
Clinical Implications
Ashwagandha at 300–600 mg/day standardized root extract produces clinically meaningful reductions in waist circumference (−3.4 to −4.7 cm) and triglycerides (−24 to −36 mg/dL) in metabolic syndrome over 8–24 weeks. Effects are dose-dependent up to 600 mg and enhanced by duration beyond 12 weeks. The intervention is well-tolerated and may be considered adjunctive to lifestyle modification in patients with central obesity and dyslipidemia.
Conclusion
Meta-analysis of seven RCTs conducted between 2023 and 2025 confirms that Ashwagandha supplementation significantly reduces waist circumference and serum triglycerides in metabolic syndrome, with moderate effect sizes and favorable safety. Optimal dosing appears to be 500–600 mg daily of standardized root extract for 12 or more weeks. These findings support Ashwagandha’s role as a safe, evidence-based option for addressing core components of metabolic syndrome.