The first is whether to go to the gym or not. Obese people will be easily injured on equipment because of lack of exercise and various complications. And because of the weight, it has more advantages in "improving yourself" sports such as pull-ups and push-ups. Here are recommended books on prisoner's fitness. You can follow the tips in the book step by step, starting with the simplest and simplest standards of each step, especially persistence and perseverance. This set of books is expensive. You can download the full trial version on Palm Reading (a reading software on mobile phone, which is highly recommended, because it can transmit by itself and also supports epub), so that the first book can be read for free (the most useful part). Pay special attention to strictly following the requirements. If you still feel unwell, you should ask questions in time (you can ask Baidu, Tianya and other forums, but it is suggested to add a fitness qq group so that you can ask questions from professional coaches), and you should not be too active, otherwise it is easy to practice badly.
Secondly, you should not eat too much or too little. Just eat in a normal amount that can keep your body running without discomfort. If you are suddenly hungry, don't be very patient. You can bring some dry food (steamed bread, soda biscuits and the like), but you should limit it. You can't eat your food here. Soda biscuits mixed with water is a very hungry combination.