teenagers testosterone levels are generally in the normal range , all depending in what stage of puberty they are, generally testosterone levels peak at 18-20. Teenagers diets suck but they are so young they can get away with it for a few years until it will catch up with them like most miidle age americans. generally lipids are adverselty affected in testosterone levels lower and higher than normal ranges 400ng/dl-1,100ng/dl . average testosterone in 25 year olds is in the 600 range