Lets do this!!!!

That would be 12 weeks, which means losing over 3 lb per week.
Are you over 400 lb?
Because that's what it would take to be able to healthfully lose 1% of your body weight every week.

If you're only 40 lb over the top end of a healthy BMI range, there's no way you will lose 40 lb of fat in 12 weeks.
You could lose water, which will return when you take a drink.
You would lose some fat, and some muscle (which is hard to regain).

If you only have 40 lb to lose, a reasonable goal at first would be 1 lb per week.
Very shortly, that will change to 0.5 lb per week as you get closer to a healthy weight.

Read this:
http://community.myfitnesspal.com/en/discussion/1080242/a-guide-to-get-you-started-on-your-path-to-sexypants

Read it several times, until the message sinks in.

Take it slowly, do this right so you can maintain the healthy weight the rest of your life.

.