I'm just trying out something new and sticking to eating vegetables and fish with most meals. Now I have a couple concerns, I do like to work out am trying to lose weight but have built a bit of a wide and more defined chest that I don't want to lose, so will changing my diet to this change me that much or will it be relatively the same? And are there any supplements I should take, currently just taking normal men's vitamin and a couple fish oil pills a day, so I'm curious if there is anything extra I should toss in with this diet?

BTW I don't work out a ton, just go for a nice 2 mile run at least 2 times a week and go to the gym 3 times a week as well (typically 30 mins on a bike, core/chest workout, leg workouts, a little lifting).

So are there any tips to give me when changing this diet?