The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content

[Display omitted] •A Mediterranean and low carbohydrate diet decreases hepatic fat more than a low-fat diet, beyond visceral fat changes.•Decreases in hepatic fat are independently associated with specific improved parameters.•The beneficial effect of a Mediterranean diet over a low-fat diet is mainly mediated by decreases in hepatic fat. It is unclear if a reduction in hepatic fat content (HFC) is a major mediator of the cardiometabolic benefit of lifestyle intervention, and whether it has prognostic significance beyond the loss of visceral adipose tissue (VAT). In the present sub-study, we hypothesized that HFC loss in response to dietary interventions induces specific beneficial effects independently of VAT changes. In an 18-month weight-loss trial, 278 participants with abdominal obesity/dyslipidemia were randomized to low-fat (LF) or Mediterranean/low-carbohydrate (MED/LC + 28 g walnuts/day) diets with/without moderate physical activity. HFC and abdominal fat-depots were measured using magnetic resonance imaging at baseline, after 6 (sub-study, n = 158) and 18 months. Of 278 participants (mean HFC 10.2% [range: 0.01%–50.4%]), the retention rate was 86.3%. The %HFC substantially decreased after 6 months (−6.6% absolute units [−41% relatively]) and 18 months (−4.0% absolute units [−29% relatively]; p