When I come across clients similar to yours, I don’t push any measurements on them. But, I do need to go over any medical issues they might have and also their health history. Beyond that, I start them on a slow easy program and try to build up their fitness level. To me it’s more important they get involved in some type of activity because it’s the first step in working towards a healthier lifestyle. I set short attainable goals which I know they can reach and then slowly I push the bar a bit higher. Measurements are not as important as achieving other more functional fitness goals. Clothes are a good way of measuring their progress especially if they are very conscious about their weight and BF%. Also, the fact that they can workout longer after a few weeks of training comparing to when they started, it’s also a great measuring point. Once you have gained their trust and they are feeling better about themselves, they might let you take all the other necessary measurements.