Lurkedforever, in response to "And when your baby is ready according to all the normal guidelines, has a stomach distended from the quantity of breast milk they are consuming and yet they still scream with hunger and don't sleep for more than 30 minutes before waking starving, having slept well previously, despite the fact you are producing enough to start a dairy, usual wind methods don't make a difference, and the only solution the hv has had since the first milder signs 3 weeks before is 'buy the hungry baby formula as its more filling', then I think actually it's ok to wean."
In that case, I would seek a professional opinion as to what was actually happening. I don't think it's a simple question of 'is this baby ready to wean' but 'is there something happening here that I don't know about?'
Given that breastmilk has far more calories in it than any early weaning foods, it is not a solution to hunger and actually you wean because their gut has matured, not because they are hungry. Babies continue to take the vast majority of their calories from milk.
In terms of sleep as well, weaning has been shown to have no positive effect on sleep whatsoever. Waking up in the night having previously slept through is now known to be nothing to do with weaning readiness and the guidelines caution against using it as a sign. In fact the evidence seems to suggest that weaning can make sleep worse for a time and not better.
If I had a baby with a distended stomach, screaming, not sleeping, problems with win etc, I'd seek medical help anyway. I wouldn't assume it was time to wean. Some babies do need to be weaned early because of medical problems and in that case the decision is HCP led. I refer to healthy babies with no clinical need for weaning.
My baby who was sitting up and crawling at 4 months, standing at 6 months and running at 9 months needed weaning no earlier than his sister who was crawling at 6 months and walking at 11 months. They both weaned around 27 weeks (and dc1 grew like a weed, from average weight at birth to 23lbs at 27 weeks). They thrived on breastmilk which is calorie dense, easily absorbed and nutritionally perfect.
I suppose it also depends a lot on your opinion. I don't and never have seen weaning as anything to do with hunger. I see it as a developmental thing. If people think that a baby waking up lots or feeding lots or watching you eat is a sign of weaning readiness then of course they're going to be convinced that the 4 month sleep regression/developmental spurt is somehow a sign. However, it isn't and I do wonder if that's where a lot of the early weaning stuff comes from.