Grandmums, mums and even 21st-century dads dole out laddoos, barfis and gulab jamuns as if they're IPOs. These Willy Wonkas with more ghee and less Oompa Loompas need to stop their Diwali-tide 'hard insisting', 'Oh, you MUST try another! You can gym it off later!' Refusing mithai should not be considered a cardinal paap whose prayaschit is to have mithai.
So, pushback on this mithai madness. And if some super-enthu Diwaliwala insists you to have mithai by telling you about it being 'tradition' and saying no would be un-Lady Diwalilike, give them your 'unDiwided' attention and then tell them with luminescent politeness, 'Why don't you stuff yourself.'