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Vilar-Gomez E, Martinez-Perez Y, Calzadilla-Bertot L, et al. Weight Loss Through Lifestyle Modification Significantly Reduces Features of Nonalcoholic Steatohepatitis. Gastroenterology. 2015;149(2):367-78.e5. PMID 25865049

One-paragraph summary

293 patients with histologically proven NASH at a tertiary centre in Havana were encouraged to adopt recommended lifestyle changes over 52 weeks (June 2009 – May 2013), with paired liver biopsies available in 261. Across the whole cohort, 25% achieved resolution of steatohepatitis, 47% reduced their NAFLD activity score, and 19% had regression of fibrosis. Degree of weight loss was independently associated with improvement in all NASH-related histological parameters (odds ratios 1.1–2.0, p<0.01). At 52 weeks 88 patients (30%) had lost ≥5% of body weight; among them 58% achieved NASH resolution and 82% a 2-point NAS reduction, against significantly lower rates below that threshold (p<0.001). Among patients losing ≥10%, all had NAS reduction, 90% had NASH resolution and 45% had fibrosis regression. In patients with female sex, BMI ≥35, fasting glucose >5.5 mmol/L and many ballooned cells, NAS fell significantly only with ≥10% weight loss.

Key findings

Weight loss NAS reduction NASH resolution Fibrosis regression
Whole cohort (n=293) 47% 25% 19%
≥5% (n=88, 30% of cohort) 82% (2-point) 58% —
≥10% 100% 90% 45%
  • Weight loss independently associated with every histological parameter (OR 1.1–2.0, p<0.01).
  • Only 30% reached ≥5% weight loss even in a supervised, high-contact tertiary programme.
  • The required "dose" of weight loss is not uniform: higher-risk phenotypes needed ≥10%.

Limitations

  • Not a randomised comparison. The ≥5% and ≥10% strata are defined by having achieved weight loss, not by allocation, so the effect cannot be separated from the characteristics of people who succeed.
  • Single centre, single 52-week window; no durability data.
  • Paired biopsies in 261 of 293 (89%) — good retention, but the missing 11% are plausibly the least successful.
  • Meta-analysis of 26 studies and 1,963 participants subsequently produced far lower pooled figures: MASH resolution 0.12 (95% CI 0.08–0.16), rising to 0.25 (0.20–0.30) with observed weight loss >3% (Jayabalan 2026, PMID 41510965).

Why it matters

It supplied the number every subsequent MASH therapy is implicitly measured against — 90% NASH resolution and 45% fibrosis regression at ≥10% weight loss — and it did so before any drug existed. It is the reason incretin therapy, which produces that magnitude of weight loss pharmacologically, carried a strong prior into MASH trials, and the reason metabolic surgery (84% resolution at five years; Lassailly 2020, PMID 32553765) remains the most effective intervention by histological endpoint. It also frames the field's real-world problem correctly: the efficacy of weight loss is not in doubt, its attainment is, and the pooled meta-analytic response of 0.12 is much closer to what unselected practice delivers than the 0.90 subgroup figure. Guidelines from AGA, ALEH and EASL all state weight loss targets that derive from this dose–response.

Cited by wiki pages

  • lifestyle-and-weight-loss.md
  • bariatric-and-metabolic-surgery.md
  • overview.md