I don't really care for the Biggest loser. On this board we aren't in competition for "money" to see how much someone can lose in a certain amount of time. It's unrealistic. After all it doesn't account for the daily hoops that the average person jumps through during the day--juggling jobs/school and kids.
Here is a great site for you to determine where you are so you can start--and on the same site that tells you how many calories you should consume to get to your goal weight.
http://www.webmd.com/diet/calc-bmi-plus
They recommend (for long term weight loss success) losing one to two pounds a week.
Judging from your tremendous weight loss two times in the past, you probably went on a pretty severe form of weird diet--only to eat a piece of bread and gain it all back--plus some.
It's time to get realistic with yourself--change some habits--and think of this as a lifetime of weight control without the word "diet" in it. IOW--a lot of times people confuse--calories with eating food that is considered bad.
A calorie is a calorie no matter how you get it. That's very important to remember.
A sugar cookie is loaded with empty calories--where an apple is loaded with healthy calories and carbs. Protein and carbs in the right amount and right way will not only help you lose weight--but it will help you to keep it off.
Make a plan--be realistic--commit yourself to a Permanent life-style change of not only watching what you're eating but how much you're eating. Eat less move more--is the key.
It's not rocket science--calories consumed in a day versus calories burned in a day. If you can invest in a Fitbit or Jawbone UP that will sync with a great free app on your smart phone and or computer called myfitnesspal that makes it very easy to keep track of the calories your consuming in a day, and the other device will determine the steps you take in a day--giving an accurate account of your calories consumed versus calories burned.
Welcome and Good luck to you!