Is there a site that can help me calculate the what-ifs of losing weight?

A safe- weight loss on a sensible program of eating well and exercising is 1.5 lbs. per week. on average.

250 fewer calories of food plus 250 calories burned by exercise daily is 500×7= c. 3500 calories/week. That’s about a pound plus a few ounces.

Livestrong.com has a calorie calculator, plus you can log workouts and adjust all of the numbers as needed. It will also allow you to track your food, so that you know exactly what you’re consuming without guesswork.

I use http://www.myfitnesspal.com/ for this.

I entered a starting weight and a weight loss goal and date.
Each day I am allotted a certain amount of calories (based on my goal) and I track what I eat and my calorie expenditures (in my case, MFP is linked to my FitBit—which is a bit like a fancy pedometer and it measures my calories expended).

It’s all free (the MyFitnessPal site is free)—except for the purchase of my FitBit..but you could enter this information manually and get the same results.

I like My Net Diary

It allows you to track what you eat, your exercise, specific elements in your diet.

I don’t know of one, but if you keep true to a good program and a healthy diet, you can be sure that you’ll see results. Special emphasis on food there, it is just as important as the workout program you follow. Also, don’t focus on your weight as a number, it can be really misleading and isn’t an indicator of how healthy you are AT ALL. BMI is one of the most horribly misguided and oversimplified metrics that I have ever seen, and in my opinion can be very, very destructive to one’s self-esteem and motivation to work out.
What you should really focus on, is taking care of yourself and feeling good! Eating the right stuff (and making sure you eat enough, very important) combined with a good workout program will have you healthy and feeling great.