When you are trying to gain weight, limit yourself to 4 servings per day of fruits and vegetables. Eat more protein foods like meats, eggs, cheese and peanut butter. And eat more starchy foods like bread, cereal and macaroni instead. Hot soups are especially good for you. In fact, soup may be a problem for you.
Soups are mostly water, and water has no calories.
In most cases, solid foods have more calories than liquid foods. If you like soup, consider making it from milk instead of water. Also, try adding extra meat, noodles, cheese or chopped eggs to it to increase the calories. Snack on raw vegetables, salad and fruit. You could find better snacks that fruits and vegetables right now.