How to gain weight

Adults should aim to increase their daily calorie intake by 300 to 500 in order to gain weight gradually.

Eat more frequently and in smaller portions, and add nutritious snacks in between.

Use cheese, almonds, and seeds to up the calorie content of your meals.

consume calorically dense beverages, like milkshakes, in between meals

maintain a balanced diet by selecting items from a range of food groups, including fruits and vegetables, starchy carbohydrates, dairy products, and substitutes.

Include lean meat, fish, eggs, beans, and pulses in your meals to increase the protein content.

keep readily prepared snacks on hand, like rice pudding or yoghurt.

Exercise can increase your appetite and help you gain muscle with strength training or yoga.

eating more often. Start eating five to six smaller meals a day gradually. To detect when you might be hungry, try to become aware of your body's signals. But even if you're not very hungry, you might still need to schedule meal times.
Selecting foods high in nutrients. Establish a pattern for eating and drinking foods and beverages that you enjoy and that are high in calories and nutrients. Consult a dietician or your healthcare professional about the recommended daily or meal intake of calories. You can also inquire as to how many servings of each food type you ought to consume.
Finish it off. To increase the caloric content of your meals, including additions like nut butter or cheese in casseroles.

Watch what you drink, though, and when. Drinks have the ability to fill you up. If it applies to you, abstain from alcohol either before or during a meal. However, be careful to consume enough liquids throughout the day.
Work out. By strengthening your muscles, exercise—especially strength training—can help you acquire weight. Your hunger may be stimulated by exercise as well.