The three macronutrients are fats (lipids), carbohydrates (sugars and starches), and protein. Fats are calorie dense and nutritionally important, nuts are a good example. Carbohydrates (starches and sugars) that release energy slowly (as measure by glycemic index and glycemic load or the insulin index) give sustained energy, such as legumes and whole grains. Some sources of protein are meats, dairy products, fish, eggs, whole grains, pulses, legumes, and nuts. These are the reasons that "trail" mix usually has dried fruit and a variety of nuts. Nuts and dried fruit can last a long time based on their expiration date. The USDA's page on expiration dates is available online.