The 28-year-old, who is mum to two-month-old Felicity and three-year-old twins Leo and Penelope, begged others to tell her it was “just a phase”.
“This is my ‘rock n roll’ Saturday night, I’m baking pastry letters,” she captioned an Instagram photo of her creation, on Sunday 6 November.
“I’ll do anything if it makes them eat! Kids make you crazy.”
Mums and dads responded with tips on how they deal with their kids who are picky eaters.
“My son is now 10 and he would only eat ham, custard, potato waffles or nothing at all,” one mum wrote. “He is getting much better now but we made a rewards board, so each new food he would get a sticker on the chart and then get a reward for a number of stickers
“To start would be to touch [the new food], then smell it, then lick it, then eat it, it’s a long old slog but we got there in the end.”
Another parent commented: “My advice to any parent is to stay calm, encourage as much as possible, don’t beat yourself up and try not to worry.
“My son is 15 next week and used to be worryingly fussy. He tried new foods on his own terms and now eats everything (it is true teenage boys eat lots).
“The best thing someone said to me is that a child eats when they need to, they will not starve themselves.”
Other parents were in the same boat as McGuinness and at a loss over what to do.
“My two-year-old barely eats and when he does it’s always the same,” one mother wrote. “I’m at my wits end with it, have a doctors’ appointment next week over it.”
Another commented: “I have one twin who eats everything and one twin who eats nothing, I never let them know how much I dread mealtimes.
“I paint a big smile on and try to make it fun.”