It was a struggle for me following any plan whilst under treatment. I lived on toasted cheese sandwiches for a while as that's all I could tolerate. Weirdly I'm now lactose intolerant.
I was advised to try to follow the food pyramid and avoid shop salads etc to reduce risks of contamination as well as soft cheeses and yoghurt due to bacteria whilst undergoing chemo. They also advised not to try to lose weight on chemo. That wasn't the issue...gaining weight was my struggle and I saw a dietitian and even following her plan continued gaining weight.
Once off chemo and after 6 weeks and with oncogist blessing I focussed on weight reduction which was low carb.