RE: What's a healthy rate of fat loss?
Whilst he may lose 7 lb for the first week or two due to water loss etc, expecting to lose this consistently, or anything like that is absolute madness.
1lb of fat is 3500 calories. That means to lose 7lb in a week he must somehow lose 24500 calories. Given that his maintenance level may be 2500 calories whereby he neither gains nor loses, simply by not eating a thing for the week will only account for 17500 calories. He must therefore burn off (over and above normal calorie expenditure ie cardio) another 7000 calories. As you can see, the idea is ludicrous. Even losing 4lb he's got to be asking himself how much of this is actually fat.
The body is programmed to hold onto fat at all costs during times of severe calorie restriction. It is a survival mechanism. Instead it will catabolise plenty of muscle to fuel bodily needs. Less muscle = less calories burned at rest as it is metabolically active. Less calories burned at rest is the last thing you want when trying to shed fat. He seriously risks becoming a "skinny fat person".