I think an imbalanced diet and the link to obesity which is very strong can have a negative impact on learning and it's probably not directly impacted as far as they aren't able to process the information and retain the information. It's likely due to factors outside of that. If the kid is larger, tends to be more apt to have bullying and things in school that were going to affect his learning ability if he is not on any balanced diet he is probably not going to be able to concentrate quite as well, so he will be off, you know maybe tired and falling asleep in class.
There you want to have that balanced diet as best you can. You want to try to bring or the reign in the childhood obesity as much as you can. There are certainly genetic factors that are beyond our control, but you do everything you can with modifiable stuff. So, get the kids active when you can, definitely make them a balanced diet if you can and it will help minimize the obesity and hopefully help them learn a little bit easier in class and or move some of those distractions they may have.