Meditation alone will not cure diseases. Meditation when combined with regular intake of Green vegetables and pulses will boost your immunity. Only then you will be free from ailments. Night blindness is caused by Vitamin A Deficiency.

My question is how much meditation is effective if one is unable to get proper diet, does it will harm the body more than, if we do meditation or not.

You should do Meditation every day during morning or evening hours for about 10 to 15 minutes. If you do not know how to do meditation you must consult an expert in your place. Of course Diet is very important. You can know all about Meditation from your Yoga  guide. Don't ever do Meditation without a guide. Otherwise, problems may arise.

There is no need for a guide to meditate nor will it create any problem to do so without one. Here is a link that gives all the details and you just have to follow it ..

https://zenhabits.net/meditation-guide/

It is  not mandatory to have a Guide. I myself learned Meditation from reading the Books on Meditation. The member who asked the question was not having any idea about meditation. My response was only for such people,

rambabu wrote:

It is  not mandatory to have a Guide. I myself learned Meditation from reading the Books on Meditation. The member who asked the question was not having any idea about meditation. My response was only for such people,

If you can read and learn so can he without any problems 

usha manohar wrote:

rambabu wrote:

It is  not mandatory to have a Guide. I myself learned Meditation from reading the Books on Meditation. The member who asked the question was not having any idea about meditation. My response was only for such people,

If you can read and learn so can he without any problems 

Then, there is nothing like that. What I had done is a friendly advice.