Most likely a side effect from Cannabis! Had friends of whom this exact issue has happened to.
Basically, you are only eating when you're high and that is when your metabolism is at its fastest. So, the energy you are consuming is being burnt up whilst high and not really giving you enough energy to sustain muscle growth/fat build up.
Then, once you fall asleep (Sleeping actually burns A LOT of energy) your body is more or less eating into its own fat stores. So finally once you wake up, your stomach is already small and you have a psychological association with only eating whilst stoned. Due to your stomach being so small, your brain will be past the hunger period and that's where your slight nausea will be coming from and it won't be until you smoke again that you will want to eat.
Here is my advice coming from a Nurse who is a regular toker.
#1 As already stated get yourself some extremely energy dense protein. Not just 100% whey protein...get something that has decent amounts of Carbs along with the protein. I.e: Something around a 50/50 ratio
#2 FORCE yourself to eat breakfast right after getting up!!! This is A MUST. You need to fill your stomach early to replenish the energy that has been lost overnight and also to allow your brain to properly realize when your stomach is getting empty so it'll trigger the hunger response.
#3 If you want to put on weight, you need to eat more than just 3 square meals a day. This is where the protein comes in. Try to have a good 2-3 servings a day. Once shortly after breakfast but before dinner. Once after lunch but before dinner. And finally, not long before you go to bed. Also try getting some good snacks like muesli bars and the like.
#4 Join the gym or take up a high energy activity like running or cycling to keep you wanting to eat.
#5 Lay off smoking weed all day everyday. Save it for the evening. Would be better to cut back a lot more, but it's not realistic to a lot of regular tokers.
#6 FORCE YOURSELF TO EAT!!!!!!!!!!!!
Wish ya all the best mate
