Key Inclusion Criteria:  Part I Healthy subjects between 18 to 55 years of age  Part II  Subjects with NAFLD Subjects between 18 to 65 years of age  Key Exclusion criteria:  Part I  A history of thyroid disease A history of, or current liver disease, or liver injuries Platelet count <150,000/mcL INR> 1.2 History of, or current electrocardiogram (ECG) abnormalities, arrhythmias or heart valve diseases judged to be clinically significant by the investigator  Part II  A history of thyroid disease Current or history of cirrhosis or decompensated liver disease AST or ALT > 5X ULN DBIL > ULN Acute or chronic liver disease other than NAFLD A history of bariatric surgery HbA1c >9.5% at screening Testosterone or estrogen replacement therapy Inducers or inhibitors of CYP3A4, including herbal therapies such as St John's Wort (CYP3A4 Inducer)