Food near most camps is cheap, fresh, and close by. Local shops and markets sit within a short walk of the training areas, so eating well between sessions is easy and inexpensive.
Training twice a day burns a lot. Most people eat a light meal before morning training, a bigger meal after, and a solid dinner. Rice, grilled chicken or pork, eggs, fish, and vegetables are everywhere. Thai portions are smaller than Western ones, so order more if you need it.
The heat matters as much as the training. Drink through the day, add electrolytes when you sweat hard, and do not wait until you feel thirsty. Coconut water is common and helps.
Compare verified camps, or prep with a US coach before you fly.