Need to lose 100 lbs in 6 months

I would recommend to go see a nutritionist with your goal. 4-8 pounds loss per month is considered healthy. I would give your self 12 to 15 months to meet your goal.

I'm not trying to be a downer here but I think your goal is a quite unrealistic. A more appropriate time frame for what you want to accomplish is most likely going to take a year at minimum. I'm speaking from personal experience because in one year I managed to eliminate 115 pounds so 100 pounds in a year is quite doable; trying to lose 100 pounds in 6 months though, however, verges on the extreme and strongly suggests that you are (or will be) losing weight in a very unhealthy manner! The only way I think you would be able to accomplish that kind of weight loss in that kind of time frame would be to quit your day job and do nothing but plan out, prepare and eat healthy meals and exercise all day long as your new full time job! As Icantnot said above: don't rush it! But don't not try either! You can reach your goal even if it takes you a little bit longer than you anticipated or would like it too and you can lose weight! Good luck and don't give up!