How can i stop overeating since i quit smoking cigarettes?

ive quit smoking for almost 3 weeks and have gone from 140 to 172lb. thats 32 pounds in 3 weeks. i was very lean and i just lost control. i used to use cigarettes as an appetite supressor with my diet but now i find it very hard to stick to a diet. its like the 3rd day that i give in. dieting is extremely harder since i quit smoking. i feel lke i have to eat everything. im gaining hella fat and i need to nip it in the bud. any advice to get my fatass moving in the right direction instead of wineing on yahoo?