Sequential changes in serum aminotransferases for obese individuals with weight losses of 25 to 170 lbs in behavioral low-energy diet program

Non-alcoholic fatty liver disease (NAFLD) is very prevalence in obesity (67%) and severe obesity (95%). NAFLD is frequently associated with risk factors (metabolic syndrome, diabetes, hypertriglyceridemia and hypertension). Weight loss with lifestyle measures improves serum aminotransferases (i.e., ALT) and liver histopathology. However, increases in ALT during weight loss raise concerns; frequent serial changes in ALT with substantial weight loss have not been reported. We examined baseline and sequential changes of ALT measured every 2-4 weeks for persons with obesity that lost substantial weight in our behavioral weight loss program. Study subjects were selected from 2 groups: Group A: 103 severely obese patients who lost >100 lbs; Group B: 136 consecutive patients with mild to severe obesity treated in our clinic. Each group was analyzed based on normal (N) or elevated (E) baseline ALT. Fewer women than men had elevated baseline ALT values. In Group A, prevalence of all risk factors except diabetes was higher among those with elevated baseline ALT (AE) than those with normal ALT (AN). Weight losses were similar in groups AN and AE, 98 lbs (24 wks) and 128 lbs (final). Baseline values were: Group AN (n=79): ALT (25.4 IU/L), AST/ALT ratio (0.87); and Group AE (n=24): ALT (68.0 IU/L), AST/ALT ratio (0.61). Peak ALT values were: Group AN: 75 ±12 IU/L (SE); and group AE: 94 ±13 IU/L. Serum ALT values after completion of weight loss were: Group AN: 24 ±1.3 IU/L; and group AE: 27 ±3.1 IU/L. For Group B, the prevalence of risk factors except diabetes was higher among those with elevated ALT (BE) than those with normal baseline ALT values (BN). Weight losses: Group BN, 24 ±1 pounds (8 wks) and 38 +2 pounds (final); and group BE 29 ± 2 lbs (8 wks) and 44 +4 pounds (final). Baseline values were: Group BN (n=105): ALT (23.2 IU/L), AST/ALT ratio (0.96); and Group BE (n=31): ALT (55 IU/L), AST/ALT ratio (0.68). Peak ALT values were: Group BN: 44 ±2.4 IU/L; and group BE: 58 ±4.4 IU/L. Serum ALT values after completion of weight loss were: Group BN: 26 ± 1.4 IU/L; and Group BE: 34 ±2.1 IU/L. We document the very high frequency of ALT elevations with weight loss but indicates that these elevations are transient and values usually return to below initial baseline values after substantial weight loss. These observations are consisted with available liver histology data indicating that weight loss is accompanied by improvement in the histopathology of NAFLD in obesity.