I agree with Wa'il,

First, fat has a lower metabolic threshold than lean muscle and other tissue, so it's calorie requirement is less (In the past, it was thought that fat was inert, it just sat there and did nothing. We now know that's not true, but even so, it's not as "active" as muscle or organs). That being said .. an extremely obese person does require more calories, since the fact of his obesity means there is more tissue, more blood vessels etc for the heart to pump blood through, etc, etc.

My concern would be that he gets enough PROTEIN. His protein needs will be high for the very reasons I stated above, even if his activity level is sedentary. He'll require more than the standard 0.6g per lb of lean body mass. Probably closer to 0.7 or even 0.8g per lb of LBM. I'm only guessing here, but I'd say a bare minimum of 120g protein per day, assuming a LBM of 150 lbs (body weight minus fat weight).

Doreen

p.s. - I think it's terrific that you're helping your friend this way