It's important throughout the day that you are reaching the correct amount of calories.
Women: 1,600 calories if not physically active, 1,800 if moderately active, and 2,000-2,2000 for active lifestyle
Men: 2,000-2,200 calories if not physically active, 2,200-2,400 if moderately active, and 2,400-2,800 for active lifestyle
Besides having your 3 meals a day you should also be snacking. You want to be eating foods that are calorie dense and not things with little nutritional value. Empty calories can include things like candy, chips, baked goods, sugary drinks, and alcohol. Some foods you can be eating throughout the day includes bananas, peanuts, low fat popcorn, eggs, yogurt, cashews, or smoothies. Get creative with your snacks but make sure you are staying away from sugary and fatty foods.
Source: https://www.nia.nih.gov