Is My Baby Self Weaning?

A customer sent us this email recently:

I have a nearly 8 month old baby boy who for the last 6 days has suddenly only wanted to feed one side at each feed. It isn’t a side preference as he feeds at both, it’s just at every feed he point-blank refuses to have the other side.
I’ve been expressing the other side to keep my supply up (and comfort!) in case it’s just a phase but on day 7 of this happening I’m beginning to wonder if he just wants less?  I’m putting the milk in his food to try and get more into him but other than that, he really is probably having around half as much as he was having the week before!
I expected he would gradually need less milk as he ate more food but didn’t expect such a rapid change overnight in his requirements.
He has 3 solid meals a day (quite a lot now where he used to hardly have anything) and is commando crawling everywhere. The one-side refusal coincided with being able to move around, which is why I thought it might only be a phase.
The first couple of nights it meant he woke in the night hungry again but the last couple of nights he’s slept through again so hopefully ok.
Could I be giving him too much solids perhaps?
Should I be worrying about this? Shall I keep persisting for longer in case it is a phase or just stop the extra expressing and accept that’s all he needs now?

Okay firstly some points:

1. it’s not uncommon for babies to change their behavior with a major jump forward in development, feeding one breast for awhile – crawling with this baby – baby thriving, sleeping, happy and content

2. Is this baby having solids first or breastmilk first?  Maybe this is the case since the mum mentioned a sudden rise in the amount the baby is eating solid food wise.

3. It is important that solids are offered first at this age, and breastmilk second.
How many breastfeeds is her baby having in a 24 hour period?

Women have so many different ideas of what is ‘big, small, good, not so good’ that it is always hard to answer these questions well without having a conversation. We’re always aware of giving clear and accurate info, especially when unable to see the mother and baby.

Our feeling is that the baby isn’t ‘self-weaning’ as such, just a natural drop in the intake of breastmilk, (always hard to say of course with such little info) however the baby is perhaps too just more efficient again, taking more in much quicker, seemingly taking less.

Breastfeeding changes so dramatically for some women when babies move through these big physical stages of development.

Your expressing question:  Probably the above questions answered first and then see where to go from there.  Ideally if all is well, expressing shouldn’t be needed.  Expressing is about building supply and of course for when the mum isn’t around.  The baby will control the supply.  You could express a tiny amount for comfort (but only as a last resort as this will interfere with your supply).  Use the fullest breast first the next time round, and check your breast a few times per day for blocked ducts.

Answered with help from Simone