I know a lot of people believe in the 'eat dinner or you can only have x/y/z' rules, and that there are certain times when children should have meals and snacks. However, I believe that by being more flexible about food, you can avoid a lot of battles in the future. And food is the one thing that children can battle you over and win - there is absolutely nothing you can do if a child refuses to eat something! I think that too many rules can set you up for eating issues and disorders later in life.
I therefore try to be extremely easygoing about when dds eat, and what. I know their favourites (right now, pasta and cheese, and apples) so I keep these foods available just about for any time. I always have a tub of pasta cooked in the fridge, and cheese handy to throw in and shove in the microwave. In fact, today, dd#2's first words (16months) when she woke up were "pasta-cheese!" Dd#1 agreed, so they had pasta and cheese for breakfast at 7am. With fresh coleslaw.
At dinner time, sometimes they eat what we're having, but often they don't want it so ask for something else. (pasta and cheese, mostly!) Sometimes they ask at a totally different time, which is not always convenient. If I'm in the middle of something, they may have to wait a while, but although it can occasionally be tiresome, I go along with them, and over the course of a day or a few days, they eat a totally balanced diet. It may not be at times that I would eat, but they are not yet adult, so I don't expect them to eat like adults.
Dd#1 (just three) does a lot of asking for food at bedtime too. If she's already cleaned teeth, she has apple. She understands why. If she's not cleaned teeth, she can choose from the things that she's allowed. She knows where these are in the fridge. She can go and help herself, pour her yoghurt drink or get out some fruit or crackers. I think this encourages independence, and I"m happy to help her if she accidentally makes a mess. Sometimes it turns out that "I'm hungry" actually means "I'm lonely" or "I'm feeling jealous of my sister", but I dont think that she is capable of knowing the real reason, so I provide the snack, then the cuddles, and don't comment if she doesnt actually want the snack when it comes to it.
I have friends who have a rule of no snacking after dinner, especially if you didnt eat dinner, and it's interesting to me that they have power battles over dinner, and over dessert, when we have no such thing. In fact, we bemuse them because when we have dinner with them, dds don't battle us over what they eat or don't eat, and then usually say 'no thanks' to dessert
Their kids definitely see dessert as desirable and vegetables as undesirable because it was always set up as being connected - you had to eat the yucky vegetables in order to get the yummy dessert. But that's a whole other post LOL.
We never react to what dds eat or don't eat. No praise for eating 'well' and no comment for not eating. Dd#1 loves having lots of little samples of different things at mealtimes. We try to accomodate this - if she says she wants corn, I'll defrost a little bowl etc. I really avoid making offerings of what we're eating or what I think they should have, and may make a couple of suggestions, but the children make the decisions. I figure that I'd hate it if someone else told me what I was to eat and when, so children must feel the same.
The result (so far) is that both dds eat an amazing amount of healthy foods. They don't touch desserts or sweets, out of choice, and will independently choose balanced, healthy meals. This approach is the polar opposite of what I grew up with, and I took it because I wanted to avoid all the food issues and power struggles of my childhood. I wanted dds to really enjoy mealtimes and snacks, and to have some autonomy over what they ate and when. However, it took a big shift for me to let go of the thought that family meals were the only 'right' thing and that parents should be in charge of food consumption.
It took a lot for me to accept mess, especially after I'd started to clear up in the evening. But now, we have systems that work for us, and no issues over what our children eat or when. The foods that dd#1 likes and can get out independently are on one shelf of the fridge. If she wants sliced apple or other fruit, I will do it and leave it on the side for her to come and help herself. She can even pull up a chair and get to the freezer to take out her frozen fruits. Dd#2 is getting the idea, and is now asking for specific snacks and meals, which I think is really cool. I love hearing a 16 month old who can make decisions for herself - especially when she is tantruming by the fridge because she wants a bowl of broccoli!
Hmm, maybe a lot of this is off topic, but it's hard to describe our approach wihtout the whole picture. I know that maybe this level of unpredictability wouldn't suit some families, but it works well for us.