You could also try taking a gulp of water with every bite. Then you fill up on more water, your brain will signal that stomach is full from water instead of food.
Something that helped my aunt is after every bite put your fork down and ask you self am I still hungry or am I just eating bc it taste good. Sometime she would take two or three bites and realize she wasn't hungry.
Chew your food more thoroughly -- that'll help you digest better and slow you down.