Brain Fog 3 Wks Post-Op

Going to phase 3 of the post-op diet this week. I hope that it provides more nutrition for my brain, because until I can think clearly I really can't return to work. I'd never be able to support my boss with this brain fog! Have you experienced this? I'm only able to get around 300 calories in considering that I can only have 1/3 cup of food per meal, and my doctor doesn't want me having snacks in between. How can I ever get enough nutrition to fuel my body and brain?