Kale
Skip iceberg lettuce and add an energy-boost to your salad by using nutrient-rich kale as a base. Kale is also great sauteed as a side dish, chopped into soups, and tossed with whole-wheat pasta. Kale contains the amino acid L-tyrosine, which may help give you a mental lift, as well as a number of antioxidants and fiber to fill you up and help keep your blood sugar stable, says Berman.