Eat more calories than you burn. Try to increase your daily caloric intake by 500-1000 calories.

Increase your protein consumption. Aim for at least 1 gram of protein per pound of body weight.

Eat 5-6 smaller meals throughout the day. This will help keep your metabolism running at a high level and fuel your body with a steady stream of nutrients.

Drink plenty of water. Staying hydrated is important for overall health and can help you gain weight by making you feel fuller and preventing overeating.

Focus on calorie-dense foods. Consume foods that are high in calories and nutrients, such as nuts, nut butters, avocados, cheese, olive oil, and fatty fish.

Include healthy carbohydrates in your diet. Complex carbohydrates such as oatmeal, brown rice, quinoa, and potatoes are important for weight gain.

Lift weights. Building muscle requires an anabolic diet and a weight training program.

Get adequate sleep. Getting enough rest each night can help your body heal and recover from exercise and other activities.

Don't try to do it all at once. Change your eating habits gradually to give your body time to adjust.