It is very important that you eat good for having good health. We see a lot of processed food at super markets / online shops which are very tasty, but they are very bad for health.
Foods like processed meat, bread, pasta, sugar, etc are things which should be avoided. Check out the full list on the link below
Avoid processed foods as much as you possibly can. I do not recommend you go completely saatvik and only eat fresh (though that is ideal). But by definition, the moment something is processed, it will be start losing its original form.