Elevated Enzymes in Teen

My 15-year-old daughter has had chronic gastrointestinal problems for years - nausea, cramping, diarrhea - they diagnosed it as IBS, but it seemed like a default to me.  She's recently tested at 191 cholesterol & elevated liver enzymes, and weighs about 185.   She obsessively craves carbs, but her diet has not been fatty.   They've told me it's just the weight that's causing a temporary fatty liver.  Can I be sure it's nothing else without any further testing?  She has insomnia, fatigue, pallor, hasn't had a period in 3 months & is not sexually active, gets night sweats, and seems very unwell for a teen.