Basically, appetite improves with better nutrition. So get the essentials in first.
1. Get foods rich in nutrients: More protein, healthy fat, whole grains, fruits and vegetables.
2. Avoid empty calorie / low-on nutrients foods: Such as chips, baked goods, sugar-sweetened beverages and candy.
3. Try high calorie/protein snacks.
4. Try high protein beverages: Such as milk, milkshakes, smoothies, soup, or high calorie and protein nutrition supplements.
5. Eat as much as you can whenever you feel most hungry.
6. Go for smaller meals throughout the day, which will help keep your blood sugar levels stable.
7. Try different foods and see what you like best: Without compromising on health, avoiding junk food.
8. Get some exercise to get the appetite going.