I went for a Pet scan yesterday and for 24 hours prior you have to follow a very low carb diet with lots of protein. Who knew diet made a difference in results. Anyway, all leafy greens, squash, green beans, nuts(not honey roasted), onions, broccoli, brussels sprouts, snow peas would be allowed, but not tomatoes. Also there is a shake that has 30 g protein and 1 carb and only 160 cals. Its Premier Protein and HEB had it. It's also cheaper than Ensure or Boost. He could replace a meal or two with these.