'Please tell Kyler that his mommy loves him so much and I’m thinking about him,' she wrote to her boy before he went to kindergarten.
But when Kyler came home, she couldn’t believe what she found.
Someone had written their own message on the note.
'No!' it read. 'Put him on a diet and go away!'
Sharing her disbelief on Facebook, Francesca’s post has gone viral.
'I sent this note in Kyler's lunchbox, thinking it would make him smile at lunchtime, but instead, I received this in return from one of the teachers,' she wrote.
She said she was in 'absolute shock' and 'disgusted'.
Francesca said Kyler was a picky eater, but she was trying to introduce healthier foods into his lunch.
'For the record, I feel that Kyler is absolutely perfect the way he is,' the angry mum wrote.
Francesca said she had now enrolled her son into a different school, and that the staff member involved had lost their job.