Pay attention to what you're eating, not just how much you're eating.
Plenty of people are familiar with the "calories in, calories out" (CICO) method of dieting which can be used for losing, gaining, or maintaining weight. This method relies on calculating a person's total daily energy expenditure (TDEE) to ensure that they are not overeating or undereating to achieve their desired weight. TDEE considers a person's height, weight, age, gender, and level of activity to determine what their caloric intake should be — some calculators can factor in body fat percentage as well. When I used a TDEE calculator online, it said that my TDEE would be 1,990 calories if I was trying to maintain my weight, but are all calories created equal? I'd argue that they're not.
It might seem obvious to some of you that 1,990 calories of macaroni and cheese are not healthy at all compared to 1,990 calories of varied foods (fruit, veggies, meat, bread, etc.).