Is it unhealthy to be a pescatarion? and do you loose weight from being one?

It is not unhealthy: I understand a pescatarian to be one which includes fish and seafood. This should be healthy as long as it is balanced with fruits, vegetables, grains and healthy fats. Many fish and seafood have helpful anti-oxidants and omega-3 fatty acids. You wouldn't necessarily lose weight unless your daily calorie intake was consistently less than your daily calorie expenditure.