Diet adjustment: increase the intake of calories and nutrients. Eat high-protein foods, such as chicken breast, fish, beans and nuts, to promote muscle growth. At the same time, increase the intake of carbohydrates and healthy fats, such as whole wheat bread, rice and olive oil. , provide energy and support muscle growth.

Eat more meals and less: eat 5-6 meals several times a day, with moderate portions for each meal, and keep eating regularly to avoid long-term fasting.

Increase protein's intake: Take enough protein for every meal, such as increasing protein's rich foods, such as chicken breast, fish and tofu.

Strength training: strength training and muscle exercise, such as weight lifting, push-ups, squats, etc. This helps to stimulate muscle growth and gain weight.

Supplementary nutrition: under the guidance of a doctor or dietitian, you can consider supplementing some appropriate nutrition, such as protein powder and amino acids, to support muscle growth and recovery.

Keep a balanced diet: In addition to increasing calories and protein intake, you need a balanced diet, including vegetables, fruits, whole grains and healthy fats.

Please note that it takes time and patience to gain weight and muscle. If you have been working hard but there is no obvious effect, it is recommended to consult a professional dietitian or doctor, who can provide personalized advice and guidance according to your specific situation.