Fruitarian diet is fruit and seeds based, and may include other foods, and not only plants (e.g. algae, mushrooms) - to answer a few recent questions at once.
Please, do not assume that fruitarianism is eating sweet fruit only. There are many kinds of fruitarians. From those who avoid seeds, if they can, to those who consider honey and eggs to be ethical choices, depending on the circumstances. Usually, fresh fruits are preferable, but the proportion of cooked foods varies. Some fruitarians soak or sprout seeds, some not. Some eat more greens or root/stem vegetables, others prefer botanical fruit, including non-sweet kinds (like tomatoes, cucumbers, squash).
Most fruitarians have ethical or environmental concerns, some may not, health or performance may be their primary motivation. There are frugans, seasonal fruitarians, freegans, raw vegans or vegetarians with high fruit intake, and so on. Everybody is welcome here :)
There is no ideal food or method, there is no competition for higher ethics or better health. The idea is to present this topic to more people for an ongoing public discussion and to share knowledge and experience.
Food energy is chemical energy that animals derive from their food and molecular oxygen through the process of cellular respiration. Humans and other animals need a minimum intake of food energy to sustain their metabolism and to drive their muscles.
Organisms derive food energy from carbohydrates, fats and proteins as well as from organic acids, polyols, and ethanol present in the diet. Some diet components that provide little or no food energy, such as water, minerals, vitamins, cholesterol, and fiber, may still be necessary to health and survival for other reasons.
Using the International System of Units, researchers measure energy in joules (J) or in its multiples; the kilojoule (kJ) is most often used for food-related quantities. An older metric system unit of energy, still widely used in food-related contexts, is the "food calorie" or kilocalorie (kcal or Cal), equal to 4.184 kilojoules.
<>Fats and ethanol have the greatest amount of food energy per mass, 37 and 29 kJ/g (8.8 and 6.9 kcal/g), respectively. Proteins and most carbohydrates have about 17 kJ/g (4.1 kcal/g).
Conventional food energy is based on heats of combustion in a bomb calorimeter and corrections that take into consideration the efficiency of digestion and absorption and the production of urine.