Carbohydrates help the body convert and store energy. Fiber is a type of carbohydrates, the peculiarity of which is that the body does not digest them. Because fiber doesn’t break down into glucose like most carbohydrates, it keeps you feeling full longer. There are many foods that contain fiber, and fiber supplements can also be helpful for maintaining energy and satiety. (Here are a few that nutrition experts highly recommend.)

Proteins help the body repair cells and create new ones. Because proteins are complex molecules by nature, the body takes a little longer to digest them, so they keep you full longer (not as long as fiber or fat, but longer than the average carb).

Finally, fats help the body absorb micronutrients, store energy, and help with other functions. Their role as assistants to other macronutrients makes them an important part of your diet.

“To make any meal truly balanced, it’s recommended to include all three macronutrients: carbohydrates, proteins, and fats,” explains Bouvier. And depending on your health goals and stage of life, your body will need a certain combination of these macros throughout the day to keep you in top shape.

It may not be possible to include all three macros at every meal, but there are plenty of hours (and meals) in the day to get all the nutrients you need. Keep this in mind when planning your lunch. Some days it may be easier to prepare or have a full meal; others not so much. Mid-day snacking can also help keep you satisfied if you include some nutrient-heavy meals.