Strong and persistent effect on liver fat with a Paleolithic diet during a two-year intervention

Background/Objectives: Our objective was to investigate changes in liver fat and insulin sensitivity during a 2-year diet intervention. An ad libitum Paleolithic diet (PD) was compared with a conventional low-fat diet (LFD). Subjects/Methods: Seventy healthy, obese, postmenopausal women were randomized to either a PD or a conventional LFD. Diet intakes were ad libitum . Liver fat was measured with proton magnetic resonance spectroscopy. Insulin sensitivity was evaluated with oral glucose tolerance tests and calculated as homeostasis model assessment-insulin resistance (HOMA-IR)/liver insulin resistance (Liver IR) index for hepatic insulin sensitivity and oral glucose insulin sensitivity (OGIS)/Matsuda for peripheral insulin sensitivity. All measurements were performed at 0, 6 and 24 months. Forty-one women completed the examinations for liver fat and were included. Results: Liver fat decreased after 6 months by 64% (95% confidence interval: 54–74%) in the PD group and by 43% (27–59%) in the LFD group ( P <0.01 for difference between groups). After 24 months, liver fat decreased 50% (25–75%) in the PD group and 49% (27–71%) in the LFD group. Weight reduction between baseline and 6 months was correlated to liver fat improvement in the LFD group ( r s =0.66, P <0.01) but not in the PD group ( r s =0.07, P =0.75). Hepatic insulin sensitivity improved during the first 6 months in the PD group ( P <0.001 for Liver IR index and HOMA-IR), but deteriorated between 6 and 24 months without association with liver fat changes. Conclusions: A PD with ad libitum intake had a significant and persistent effect on liver fat and differed significantly from a conventional LFD at 6 months. This difference may be due to food quality, for example, a higher content of mono- and polyunsaturated fatty acids in the PD. Changes in liver fat did not associate with alterations in insulin sensitivity.