New items don't get added to the view

I have something like:

var messages by remember {
    mutableStateOf(emptyList<Message>())
}

fun load() {
    messages = listOf(Message(), Message(), Message(), Message(), Message())
}

fun loadMore() {
    messages += listOf(Message(), Message(), Message(), Message(), Message())
}

LaunchedEffect(Unit) {
    load()
}

LazyColumn {
    items(messages) { Message(it) }
    item { LaunchedEffect(Unit) { loadMore() } ; Loading() }
}

However only the first load is shown, no new items are getting added.