Hello, I can understand it's difficult to adjust to new places in matter of food.  In that case you can try to consume more of calories rich foods like Banana, mangoes, chickoo, grapes. You can also include non vegetarian food like chicken, fish, eggs if available and if you eat. If you dnt get all these food you can keep nuts and dried fruits handy with you. These food will give you more calories and also provide essential minerals and vitamins to increase stamina. Also since you have been consuming marijuana since years it has effect your body organs and also lower your immunity and stamina. It would be great if you can stop having it. It would  be difficult but not impossible. For detail diet chart you can message in personal.