Eat more calories than you burn
Add calorie-dense foods like nuts, nut butters, avocado, cheese, olive oil, whole milk, and dried fruit
Increase meal frequency to 3 meals and 2 to 4 snacks per day
Choose larger portions at meals
Drink calorie-containing beverages like milk, smoothies, and protein shakes
Focus on protein-rich foods such as eggs, dairy, meat, fish, tofu, beans, and lentils
Include complex carbohydrates like rice, pasta, oats, potatoes, and bread
Add healthy fats to meals and snacks
Strength train regularly to build muscle
Limit excessive cardio
Track your weight weekly
Aim for gradual weight gain
Sleep enough each night
Manage stress
See a doctor or dietitian if you are losing weight unintentionally or have trouble gaining weight