This shows that the thicker oat flakes have a lower GI when compared to the finer oats.
I’ve also found that cooking the porridge for longer, kept me full for longer. One bowl (40g raw, 120ml milk) for me takes 5 mins in the microwave. I’m good until lunch. A friend who also has porridge for breaky, same amount, cooks his for 2 mins and complains he’s hungry a few hours later.
I did read that somewhere too but cannot find it now.