Hi there, well there is a very high correlation between VO2 and body fat, ie the higher the VO2 the lower the body fat of the person, but there are always exceptions to the rules, that is what makes our job so much fun, ah the individual nature of genetics, it is just the size of the engine in the machine (central issues), as well as the peripheral issues (mitochondria etc), and two people are the same, I have th esame situation with 2 of my props, but you have tio ask the question would the prop who is 20% be even better if he were to drop to 15%, and is it worth spending all that time getting him there in the first place if he can still do well aerobically, so your question will produce many more I am sure, all good, ashley