I usually eat a can of tuna right after I work out and it has been working well it seems. I now want to but the case of MET-RX protein powder shake which is a meal replacement. I heard that these are meant to replace a meal, and that they have a lot of protein in them. My question is could I drink one of these with my tuna fish, or should I have tuna fish then wait a few hours and have a MET-RX or MET-RX then tuna a few hours after. Thanks!

Look at the fat content in the Met-RX. If there is more than 2-3g, do not use it immediately post workout. It will slow your body's digestion/absorption of the protein and carbs, but it would be ok for your second meal about an hour and a half later. If there is little fat in it, I would recommend the shake right after the workout, wait 1.5 hours and then the tuna (and a bit of starchy carb food). Is muscle gain your goal right now?

Shake first, then tuna. Shake is predigested for the most part so the nutrients get right to work on the body while a solid food such as tuna takes time to break down in the stomach into usable nutrients. Shakes are best suited for right after a workout as the body needs nutrients quickly and that's the quickest way to get them.

Look at the fat content in the Met-RX. If there is more than 2-3g, do not use it immediately post workout. It will slow your body's digestion/absorption of the protein and carbs, but it would be ok for your second meal about an hour and a half later. If there is little fat in it, I would recommend the shake right after the workout, wait 1.5 hours and then the tuna (and a bit of starchy carb food). Is muscle gain your goal right now?
Thanks for the replies guys and yes my goal right now is to lose my body fat (which is very little I used to be really skinny now I have a lot more muscle) and turn it into muscle. I don't want to be one of those huge bodybuilder guys just really cut and strong. Ive been working out religously for about 3 months and have noticed a big improvement, and so have people around me so it makes me feel so much better about myself and I'm really glad that I started.