The key thing for me in the OP is not the 'snacks' (which, as has emerged on this weirdly fascinating thread, seem to mean very different things to different people in terms of what is consumed, and when, and how much), it's the fact that portions were strictly controlled at the (widely-spaced) meal times too.
My SIL and BIL do this - I think previously foodie BIL has picked it up from his wife, whom I like, but who bristles with food 'issues' and thinks that enjoying food isn't 'nice' - spending a weekend at their isolated house does mean SIL serving tiny, salt less portions and watching how quickly you eat and whether you will wait for hervtobreluctantly offer second portions. A typical lunch comprises of a half-bowl of soup without bread. Everything is served in the kitchen, no putting of dishes of food on the table. Her children are praised for leaving food on their plates. (It was funny until we had our son, when it became more problematic -now we bring food, as there is nowhere to buy it locally.)
Being a good host does mean responding to your guests' needs. We had friends over from France with their children for a weekend recently, and realised immediately we had underestimated how much food needed to be made. DH and I are on the small side, rangy and narrow-framed, and we have a toddler who is currently completely uninterested in food (though perfectly healthy). Our friends are very tall and large-framed, and their equally big children (whom we hadn't seen in years) are a lot older and hungrier than our son, which of course explains a lot, but we were initially taken aback, as we thought we had over-catered.
It was interesting to see how much more our adult friends ate in order to be satisfied, compared to us, when we are the same ages and roughly equally active. I really liked seeing things I'd made eaten with such relish, actually!