'No thanks Gran, I'm full' *piles more food on plate* 'Oh well, if you insist...'

And then I wonder why I put so much weight on over the holidays.

I'm starting to think that as soon as your first grandchild is born, some sort of switch must flip in your brain turning on GRANDMA MODE. Feeding becomes an obsession for them. 
You can tell them you dropped out of Uni: not a problem, maybe studying wasn't really your thing. 
You robbed a bank: no worries, I'm sure you needed the money. 
However, if your answer to the question 'Have you eaten yet?' is 'No'... well, prepare yourself for a barrage of food. A banquet fit for twenty odd people. And if your Grandma is anything like mine, all that food will be produced after her complaining about not having anything to eat. 

'Oh honey, you should've called before coming round. I would've made you something nice. I barely have anything for lunch today.' *bam!* She produces a roasted chicken from the oven, including side dishes.
Although sometimes, I think she just enjoys complaining. She does it regardless of if you ring her or not. If you don't go round to see her, she'll ring me (or my mother) and bitch because all her food went to waste. And if you go round without calling... well, refer to the sample conversation above. No way to win really. 
And if you don't answer her call, all you have to do is wait 20 minutes for one of my aunts to ring and complain about the phone call she just received. One of the perks of having a huge family: we're all interchangeable at times - mainly, when my Grandma needs someone to complain to.
To be fair, my Grandma is used to cooking for about 300 people, or what's the same, her 10 kids (which have the combined appetite of the aforementioned 300). So, she always has leftovers as well as a well developed empty-nest syndrome which results in her over-feeding her numerous grandchildren. 
And this would all be fine with me (I mean, who doesn't love to be pampered with food?), if once she were done with the feeding she wouldn't stop to give me a critical once-over and go: 
'Hmm... you're getting a bit chubby, don't you think? Maybe you should cut back a bit.' 
Unluckily for me, my family has a stupidly fast metabolism which means they can inhale food at alarmingly fast rates and still be a size 6/8. Hence the fact that all my Gran's pots and pans are massive. I'm not sure the woman knows how to cook for two... But anyway, this 'chubby' comment (sometimes followed by, 'Maybe walking a little more would help.') usually results in my aunts sniggering behind their hands (very adult hmpf), my mom face-palming and me generally confused. 
'Erm... Gran, I don't usually eat this much, you should know this...'
'Well, just say so! I won't serve you as much next time.' 
'But... I tried, the look you gave me was scary.'
'Oh, don't be silly! Now here, stop sulking and have some fruit for dessert. The neighbours just brought me some apples, I'll drizzle the pieces with honey.'
... And of course, I can't say no.