My ast level was 54 and my alt is 21. i was negative for hepatitis c and antibodies. i dont drink alcohol or take meds. im not obese bmi is 22, and im vegetarian, intermittently fast. what could cause this? abdomen is flat?

Given normal level of ALT, mildly elevated AST is unlikely from liver pathology. AST can be elevated in association of pathology in skeletal muscle, kidney, myocardium, or red blood cells.

Did you not say in another message you exercise strenuously? If you did that would explain the elevated AST. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV and Covid vaccines. Wish you good health!