Funny enough, I have dropped about 60 lbs at your friends age, then again at about 27 years old, and I'm doing it again in my mid-thirties. (Sigh. This will
so be the last time I do this!)
The weight came off pretty quickly in my twenties. This time it's still coming off at a good rate (2 lbs per week), but in the beginning it was kind of erratic. But that had more to do with my diet than my age, since my diet was erratic too.
In comparing my experiences, I would say that I'm losing at about the same rate as I did the first two times. I credit my weight loss, and the rate of loss, to diet and exercise. Age hasn't affected it one bit, although I had feared it would.
But, maybe I'm just one of the lucky ones who can lose weight "easily."
(Although I would argue there is really nothing easy about it at all -- I'm just working my butt off to achieve it and my body is cooperating with my efforts!
)