Just concerned on the 4th seizer my dog just had. Does overweight issues have anything to do with triggering them or is it all just nerves in their brain?

I found this site about dog seizures.

A brief overview of seizures (http://www.canine-epilepsy.com/overview.html)

They can be caused by different things so it is best to get the vet to diagnose him.
Seizures can be caused by a variety of things including both primary and secondary epilepsy. They can also be the result of a blow to the head, calcium deficiencies in nursing mothers, end stage heartworm disease, toxic plants, chemicals, fertilizers and poisonings. There is even evidence that seizures may be have a hereditary factor involved since there are several breeds such as the Sheltie, Belgian Tervureren, German Shepherd, Dachshunds and others that have a higher incidence of them than other purebred dogs.

How to Avoid Food Triggered Seizures (http://www.wikihow.com/Avoid-Food-Triggered-Seizures)

My dog has epilepsy and started having seizures when he was 5 years old. The vet prescribed medication but it made him nauseous and despondent. Another vet recommend adding green beans to his diet and taking him off the meds. He now gets green beans once a week and hasn't had a seizure in almost 7 years, he will be 13 years old in May.

My dog has been epileptic since jan 07 and has had over 100 fits in the last year. He has had loads of tests and nothing seems to be wrong but he still has fits. He takes medication twice a day to try to control the seizures but as of yet nothing seems to work I have recently changed from feeding him dried dog food to preparing him fresh food I cook myself and the fits have been further apart but sometimes you are not able to control them and you just have to live with it as long as the dog isn't affected too much