Although I agree that he might be going to low in calories, if he bumped his calories up 700 he would have to do cardio for half the day just to achieve the same calorie deficit. I have always thought anything above walking cardio as a high impact type of activity especially for anyone with a significant amount of extra weight. You could begin a resistance training program (I would increase your cals a little if you go this route, your inc would be to just eat more lean protein) and if you have never weight training or haven't done it in a while you should gain some muscle in the beginning which would aid in your weight loss.