I can vouch for this too.

I lost a preemptive couple of kilos in anticipation of Christmas. I lost them by doing nothing more than not eating after dinner.

The small plate thing works too. When I am eating with the kids on my own I will often just eat off the same size plate as them. In fact, I was thinking there could be a market in bringing out a range of dinnerware 20% smaller than average. Dragons' Den anyone?