Efficacy of Structured Lifestyle Intervention in Normal Body Mass Index Non-alcoholic Fatty Liver Disease

Lifestyle modification remains the cornerstone of non-alcoholic fatty liver disease (NAFLD) management, but its efficacy in lean or normal-Body Mass Index (BMI) patients is inadequately studied. We evaluated the effect of structured lifestyle intervention on liver biochemistry and stiffness in patients with normal-BMI NAFLD.

This prospective, controlled interventional study enrolled 120 consecutive patients with ultrasound-detected hepatic steatosis, elevated liver enzymes, and BMI <23 kg/m². Participants were allocated to intervention (n = 60) or control (n = 60) groups using a non-randomized, preference-based approach based on willingness for intensive counseling. The intervention comprised structured dietary counseling, prescribed aerobic exercise (150-200 min/week), and weekly telephonic follow-up for 6 months. Controls received standard verbal advice. Changes in liver stiffness and serum levels of aspartate aminotransferase (SGOT) and alanine aminotransferase (SGPT) were assessed at 1,3 and 6 months.

Baseline characteristics were comparable between groups and retention was excellent (100% intervention, 95% controls). At 6 months, the intervention group showed greater reduction in SGPT levels (-23.1 U/L, 27% decrease, P < 0.001) versus non-significant change in controls (-18.4 U/L, P = 0.147), with between-group difference of -18.7 U/L (P < 0.001). Similar reductions were observed in SGOT (-16.0 vs. -1.3 U/L, P < 0.001) and liver stiffness (-0.76 vs. -0.12 kPa, P < 0.001). The SGPT normalization was achieved in 18% versus 0% (P < 0.001; NNT = 5.5), SGOT normalization in 50% versus 10% (P < 0.001; NNT = 2.5), and liver stiffness normalization in 55% versus 17% (P < 0.001; NNT = 2.6). Benefits were consistent across diabetes status, steatosis grade, and age subgroups. BMI showed a modest non-significant reduction in the intervention group while remaining within the normal range.

In this non-randomized preference-based study, structured lifestyle modification with dietary counseling, prescribed exercise, and systematic follow-up was associated with significant improvements in liver biochemistry and stiffness in normal-BMI NAFLD patients, independent of weight loss. The preference-based design and high motivation of participants should be considered when interpreting these results.