Gamma gt= 42 ul/ litre. Is it ok for an african obese woman?

Don't treat a lab. This worries me just a bit. I understand you are overweight and if the other liver enzymes are on the high side, this may your body's way of letting you know that it wants less to eat and more opportunities to exercise. If your physician is not overly concerned, I would not be either -- it's the very high values of GGT that usually are tip-offs to serious illness.