Does childhood obesity usually distort the liver tests?

It might. Obesity is a disease in itself and can effect many organs in the body. As I have said in many answers sugar in all its forms is the main culprit, even diet drinks because they produce what is known as oxidative stress. Particularly in the lower brain that computes are ability to adapt to changes in the environment. Poor nutrition is the clue.
It may. Children with childhood obesity may have abnormal liver function tests due to insulin resistance. The body cant handle the sugar and some of it gets deposited in the liver. Eventually you get a FATTY liver which causes inflammation and affects the liver function tests. It is reversible with weight loss and improved eating habits.
It can. We see fatty liver disease in many of our patients with obesity. Not all people with obesity have this, however.