Protein has 4 calories per gram and fat has 9 calories per gram. Carbohydrates consist of sugars, starch and fiber and have 4 calories per gram. Vegetables have varying amounts of protein, fat and carbohydrates, so the total calories per gram also varies.
Alfalfa sprouts, artichoke, bamboo shoots, broccoli, cabbage, cauliflower, celery, cucumber, eggplant, bean sprouts, turnip and rutabaga, spinach and tomato all have approximately 20 calories per 100 g, or 0.2 calories per gram. These vegetables are mostly water and fiber and are rich in vitamins, minerals and other antioxidant compounds. Pumpkins and other winter squash have 26 calories per 100 g, or 0.26 calories per g.
Starchy vegetables such as peas, carrots, potatoes, corn and sweet potatoes have significantly more calories. Potatoes have 60 calories per 100 g, sweet potatoes and corn have 86 calories. Peas have 81 calories, carrots have 41 calories.
Green beans, kohlrabi, mushrooms, okra, pimentos and zucchini have 30 calories per 100 g, or 0.3 calories per gram.
The U.S. Department of Agriculture food pyramid recommends that you eat 5 or more servings of vegetables a day. A 100-g serving is roughly 3.5 oz. Vegetables are rich sources of nutrients and have relatively few calories compared to other foods. However, cooking them in oil, butter or cream sauces can add significantly to the calories.