When I moved to Korea, I had to rebuild my food system from the ground up. The American bodybuilding foods I was used to were not always convenient, affordable, or available in the same form. That forced me to get practical fast: if I wanted to keep progressing, I needed Korean foods and convenience-store fallbacks that could support training instead of fighting it.
The first rule is still protein. Research on resistance training shows that protein supplementation and higher protein intake can support gains in muscle mass and strength, especially when total intake was previously too low. In real life, that means your first question at CU or GS25 should be simple: where is the protein coming from? Chicken breast packs, eggs, tuna, Greek yogurt, protein drinks, and lean meat lunch boxes are usually the safest starting points.
The second rule is not to let Korean convenience foods trick you into eating mostly carbs and sauce. Rice balls, kimbap, ramen, pastries, and sweet drinks are easy to grab, but they can leave protein too low and calories too high. I am not against carbs. I use rice constantly. But carbs should be placed around training and portioned with intent, not added accidentally because the protein option was weak.
For muscle gain, I like simple combinations: chicken breast plus rice, eggs plus yogurt, tuna plus a carb source, or a protein drink added to a normal meal that is too low in protein. For dieting, the same foods still work, but the portions change. The most successful clients are not the ones who find perfect foods. They are the ones who build repeatable meals they can execute on a busy Tuesday night.
My experience in Korea changed how I coach nutrition because it reminded me that a plan only matters if it survives the environment. A macro target written on paper is useless if the client cannot find food after work, between classes, or near the gym. The better skill is learning your local options so your diet keeps moving even when your day is imperfect.