I've noticed this as well. For the past 10 years or so at least, I've eaten several times a day. Smaller meals here/there. However, some days at work, we have to have lunch out and on those days, I'll eat a few smallish things in the morning and then I'll have a bigger lunch at noon. When I do that, at 3pm, I am famished...absolutely starving! Even though I ate smallish things in the morning and had probably twice what I would have eaten normally at noon, I am still famished at 3pm. (Normally, eating some small things in the morning and then again at noon, 2, 4, and 6 is sufficient.)
I used to think that it was only because of what I was eating at the work lunches. Our work had a tendency to eat at this Middle Eastern place and the stuff that I'd get (same thing every time) was carby and low on protein. However, I still get famished even if I have something like grilled chicken and steamed veggies at noon.
I've learned that when we have those work lunches, I have to treat the noon meal as any other small meal and then still go back and have something at 2, 4, & 6. (I just dislike explaining to people why I'm ordering something so tiny and most of them usually try to talk me into getting something bigger despite my explanations.)