I hate the idea of forcing children to eat, by whatever means.
DS was a TERRIBLE eater for a long time, (fussy, faddy and also only ate tiny quantities) and was small and skinny and on a v low centile. But within that great range of centiles, some kids will naturally be on it! It's if they're OFF the centiles that there is a problem, and the idea isn't to get each kid as close to the middle line as poss!
I did stop DS running around and getting up and down - I was firm about him staying put at the table, and we did a sticker chart for that. But while he was there, I didn't pressurise him to eat, and made sure that he had food that h liked. I have never made a holy grail of pudding. Mostly we have not had it at all, and if we have I have never made it a reward for eating other food. In fact once, DS was eating spag bol, spotted some choc buttons, mithered for them, and to the horror of another parent present, i gave him one, put them out of sight, he ate it, and then went on with his dinner. Neither have I made any song and dance about not having chocolate or sweets. If we fancy some, we have a reasonable ampunt and enjoy it without comment.
After eating a v small range of food between 2 and 4.5, DS, now 8, still has quirky fads, is suspicious of fruit and veg, but otherwise is an adventurous and enthusiastic eater. Still v small, but that's hi, and that's WHY he doesn't eat great big platefuls of food!