That's pretty fast, but probably doable.
Note that if you push yourself too much, eating can become a chore and not as enjoyable as you might like.
I'd say go ahead and gain the 40 pounds but don't worry about the time limit too much.
Also, when gaining weight like that it can be hard to stop exactly where you plan. It's very common to overshoot by a few pounds. Don't stress about it if you do.
Note that if you push yourself too much, eating can become a chore and not as enjoyable as you might like.
I'd say go ahead and gain the 40 pounds but don't worry about the time limit too much.
Also, when gaining weight like that it can be hard to stop exactly where you plan. It's very common to overshoot by a few pounds. Don't stress about it if you do.
11 years