Meal Portion Size as it relates to BMs?

I am the same way you describe, always have been as well. I eat small meals/snacks throughout the day, and a good size dinner. When I had UC, I didn't eat much at all. The less I ate, the less I went. The problem is that you can't live like that forever, also, you will notice that when you do eat, you will have a lot of unpredictable trips. I noticed that no matter how little I ate, I'd still end up on the toilet for an hour in the AM, unless I ate nothing at all of course, then I could get through the day feeling pretty confident I wouldn't need the toilet, and if I did it wouldn't be much. I personally don't think more smaller meals would be helpful, but I also don't think limiting food intake to a level that is unhealthy is ever a solution. It's something we can tolerate for short periods, but ultimately you need to find something that gets you to a point where you can live well. Do you ever get up in the night to go?

Less cumulative input = less cumulative output in a lot of cases; timing of light/big meals does not matter. However, you cannot starve yourself indefinitely as a way of managing an UC. What you eat can impact output as well. High fiber from healthy fruits, vegatables, breads, etc can cause more output. Eating mostly processed foods (which are very low in fiber), eating mostly meats (low in fiber), can decrease output. Drinking lots of fluids can increase output when you're flaring. Drinking less liquid dehydrates and decreases output. Of course not all of those things are healthy to do.

In the end, treating the UC and getting into a remission is always the best answer. As in a remission you might poop once a day, and the food management/timing is a total non issue.