Background

While visceral adipose tissue (VAT) and hepatic fat content (HFC) are independently associated with metabolic syndrome and type 2 diabetes,[1][2] some researchers have suggested that HFC mediates the relationship between VAT and metabolic syndrome.[3] Although hypocaloric dietary interventions are necessary to decrease total body fat, carbohydrate-restricted diets may be superior for decreasing HFC.[4]

The study

This 18-month study assessed the effects of a low-carbohydrate Mediterranean diet on HFC and VAT, compared to a low-fat diet. The researchers also investigated whether decreases in HFC conferred benefits independent of VAT changes. They randomized 278 participants with abdominal obesity or dyslipidemia to a low-carbohydrate Mediterranean diet or a low-fat diet for 18 months. After the first six months of the intervention, participants were further randomized to an exercise or non-exercise condition.

MRI was used at baseline, 6 months (for 157 participants), and 18 months to assess changes in HFC and VAT. The researchers also collected fasting blood samples to assess fasting glucose, insulin, blood lipids, and insulin resistance. The primary outcome was the influence of HFC reduction on cardiovascular markers after controlling for changes in VAT.

The results

After adjusting for VAT changes, reduced HFC was independently associated with improved gamma-glutamyl transferase, alanine aminotransferase, chemerin, and HbA1C. All participants experienced improvements in cardiometabolic risk markers (blood lipids, gamma-glutamyl transferase, and fasting insulin) and decreases in HFC. However, the participants in the low-carbohydrate Mediterranean diet group had a greater reduction in HFC than the participants following the low-fat diet. After adjusting for VAT, the low-carbohydrate Mediterranean diet resulted in greater improvements in blood lipids, blood pressure, and cardiovascular risk score.

Note

The low-carbohydrate Mediterranean diet group decreased their energy intake by 26%, compared to the 22% decrease in the low-fat diet group. However, this difference was not statistically significant.

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This Study Summary was published on January 5, 2021.

References

  1. ^Patrick Mathieu, Paul Poirier, Philippe Pibarot, Isabelle Lemieux, Jean-Pierre DesprésVisceral obesity: the link among inflammation, hypertension, and cardiovascular diseaseHypertension.(2009 Apr)
  2. ^Geoffrey C Farrell, Claire Z LarterNonalcoholic fatty liver disease: from steatosis to cirrhosisHepatology.(2006 Feb)
  3. ^Elisa Fabbrini, Faidon Magkos, B Selma Mohammed, Terri Pietka, Nada A Abumrad, Bruce W Patterson, Adewole Okunade, Samuel KleinIntrahepatic fat, not visceral fat, is linked with metabolic complications of obesityProc Natl Acad Sci U S A.(2009 Sep 8)
  4. ^Jeffrey D Browning, Jonathan A Baker, Thomas Rogers, Jeannie Davis, Santhosh Satapati, Shawn C BurgessShort-term weight loss and hepatic triglyceride reduction: evidence of a metabolic advantage with dietary carbohydrate restrictionAm J Clin Nutr.(2011 May)