Waist not weight: Key to non-alcoholic fatty liver disease

NAFLD is a condition in which fat builds up in the liver. In some cases this accumulation of fat can cause inflammation of the liver and eventually lead to permanent scarring (cirrhosis), which can seriously impair the liver's ability to function. NAFLD is a condition strongly linked to obesity, with a reported prevalence as high as 80% in obese patients.1 The 'lean' form of the disease can lead to diabetes, high blood pressure and even death,2,3 and has been reported in 16% of individuals with a normal body weight.1

"While NAFLD is commonly associated with obesity, research has highlighted that a percentage of patients are not actually obese," said Dr Rosa Lombardi, Unit of Internal Medicine, Policlinico Hospital, University of Milan, Italy and lead study author. "This is the first study to show that patients with lean-NAFLD who have increased levels of waist fat can in fact be at greater risk than obese patients with NAFLD."

The researchers in the Italian study evaluated the features of lean-NAFLD in 323 patients with biopsy-proven NAFLD. Subjects were divided according to BMI (<25kg/m2 defined as lean-NAFLD), waist circumference and abdominal fat.

The study found that NAFLD patients with a waist circumference greater than 35/40 inches, females/males, respectively, was significantly associated with metabolic syndrome (p=0.001) (the combination of diabetes, high blood pressure and obesity), carotid plaques (p=0.03) (the build-up of fatty substances and cholesterol deposits in the carotid artery), and significant fibrosis (p=0.03) (the first stages of liver scarring), compared to obese patients with NAFLD. This was true even in patients with normal weight (lean-NAFLD).

The research also suggested that metabolic, cardiovascular and tissue complications caused by NAFLD can be more effectively detected by combining Body Mass Index (BMI) and waist measurements.

"This study has proven to us that the severity of non-alcoholic fatty liver disease is not necessarily linked to how obese an individual is, but instead how much fat build-up they have around the waist," said Professor Frank Tacke, EASL Governing Board Member. "The results have highlighted the need for additional research into why analysing someone's waist, and not just their weight, is important in detecting individuals at risk for complications associated with this disease."

References

1 Milic S, et al. Non-alcoholic fatty liver disease and obesity: Biochemical, metabolic and clinical presentations. World J Gastroenterol. 2014; 20(29):9330-9337.

2 Ren-Nan Feng et al. Lean-non-alcoholic fatty liver disease increases risk for metabolic disorders in a normal weight Chinese population. World J Gastroenterol. 2014; 20(47):17932-17940.

3 Dela Cruz AC, et al. Characteristics and Long-Term Prognosis of Lean Patients With Nonalcoholic Fatty Liver Disease. Gastroenterol. 2014;146(5) Suppl 1: S-909.