Im 25 i lost like 10 pounds cause i been sick i have a high metabolism how could i gain weight i recently bought some ensure ?

To gain weight: Healthy fats and oils have the most calories and are best to gain weight. Nuts, peanut butter, avocados,wole milk, and olive oil are some. Other foods like protein shakes and dried fruits,whole grain bread,some cheese and red meat are other weight promoting foods. If you have trouble gaining weight, make sure you don't have an overactive thyroid or diabetes.