1 Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine and Sylvan Adams Sports Institute, Tel Aviv University, Israel.
2 Soroka University Medical Center, Beer-Sheva, Israel.
3 Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
4 Soroka University Medical Center, Beer-Sheva, Israel; Nuclear Research Center-Negev, Dimona, Israel.
5 Nuclear Research Center-Negev, Dimona, Israel.
6 Department of Medicine, University of Leipzig, Germany.
7 Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard School of Public Health, Boston, MA, USA.
8 Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. Electronic address: email@example.com.
BACKGROUND & AIM:
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?<0.001 vs. baseline). Reductions of HFC were associated with decreases in VAT beyond weight loss. After controlling for VAT loss, decreased %HFC remained independently associated with reductions in serum gamma glutamyltransferase and alanine aminotransferase, circulating chemerin, and glycated hemoglobin (p?<0.05). While the reduction in HFC was similar between physical activity groups, MED/LC induced a greater %HFC decrease (p?=?0.036) and greater improvements in cardiometabolic risk parameters (p?<0.05) than the LF diet, even after controlling for VAT changes. Yet, the greater improvements in cardiometabolic risk parameters induced by MED/LC were all markedly attenuated when controlling for HFC changes.
%HFC is substantially reduced by diet-induced moderate weight loss and is more effectively reduced by the MED/LC diet than the LF diet, independently of VAT changes. The beneficial effects of the MED/LC diet on specific cardiometabolic parameters appear to be mediated more by decreases in %HFC than VAT loss.
High hepatic fat content is associated with metabolic syndrome, type 2 diabetes mellitus, and coronary heart disease. In the CENTRAL 18-month intervention trial, a Mediterranean/low-carbohydrate diet induced a greater decrease in hepatic fat content than a low-fat diet, conferring beneficial health effects that were beyond the favorable effects of visceral fat loss. ClinicalTrials.gov Identifier: NCT01530724.