Starvation for diarrhoea was always nonsense. Something I recognised over 40yrs ago when it was still being bandied about and passed on from old f@rt vet to young junior.
There is a logic where the patient has vomiting as well as diarrhoea and you need to rest the excessive gastric stress of dramatic vomiting ( I've seen stomachs heave so much they've bruised themselves and bled) but it never made sense to me for typical diarrhoea and I battled against it most of my career when new associates joined my practice.
Just think about it. The bowel is designed to move stuff along and absorb it. What causes diarrhoeas? It's either stuff moving along too fast or stuff not being absorbed. Whatever the cause: tumour infiltarion, infection, irritation, hypertonic food if you stop feeding the pet then there's nothing to move along or to absorb. It's not solving the problem and in reality will hardly make any change to signs.
What you need to do it to replace fluid losses where not enough is being absorbed or where it's actively being secreted into the bowel and keep the patient as fit as possible..providing energy - which is food. Yes, you want to feed frequent small amounts to allow abnormal bowel contraction to cope with it and avoid vomiting, yes you want to feed a known 'safe' i.e bland diet rather than aggravate an inflammatory or intolerant diet but your aim is to keep the patient fit and functional.. not hungry and dehydrated.
The typical simple dog diarrhoea from eating inappropriatly.. from the cat litter pan, x/s horse dung etc or just a mild tummy 'bug' or transitory inflammation or a depression in happy gut bugs is going to sort itself so long as you don't make it worse. You can ease the patient's discomfort - help it pass wind with peppermint, adsorb toxins in charcoal, thicken a runny straining diarrhoea with kaolin, help a colitis with appropriate fibre, replace disturbed happy bugs with lactobacilli supplements - all as necessary. But always keep in mind that patients are organisms very well designed to heal from most mild to moderate insults so long as you don't interfer with that process...and it takes fluids, electrolytes and nutrition to fuel the engine.
The real trick is in making an assessment and being right when patient is better off without meds and just needs a little nursing.