So sorry for the delayed response. I was away at a conference and have been playing catch-up since I returned.
I think your idea for combining one of your carbohydrates with a protein is a really great idea!
bumblebee27 wrote:so thinking about
Remember to include a control, by measuring the same carbohydrate alone.
Otherwise, I think this is a great plan. Any reason you are avoiding red meat here? I like the use of chicken, fish, and lentils (for a vegetarian/vegan option), but I think it would also be interesting to look at red meat. Of course, I only suggest this if it is not a problem to add another trial for your subjects. If 4 trials (control, fish, chicken, lentils) is as much as you are willing to inflict on your subjects, I think it's a well-rounded design and you will be good to go.
By the way, I wanted to address your other idea regarding the genetically modified foods. Honestly, I do not see any reason that genetically modified carbs should affect GI any differently than non-modified carbs. (The exception would be if they were specifically modified to exhibit a lower GI.) Most genetically modified foods are modified for pest resistance and/or flavor, which are genes that would not necessarily affect the GI. Basically, I think you picked the better project idea from the two you listed. (Again, sorry for taking so long to get back to you.)
Please keep me posted as you continue with this project! I really enjoyed helping you with the original project, and I am looking forward to seeing what happens with this one.