There is this thing that my dad does once a year in February he don't eat meat for 40 days and I want to know if I would lose some weight
We eat nothing but veggies and fruit and no starches

Don't quote me on it.. but I do believe there are starches in some veggies... i.e. potatoes.. I don't think eating meat would make you loose weight because it contains protine that we need for our bodies.. but I may be wrong. I hope someone helps you with your question

It depends what you eat instead. Most of the vegetarians I know are fatter than they would like, they end up eating a lot of fat and starchy things instead of meat.