energy resp / energy constraint / net energy acquisition / energy exchange prices / food items / energy optimization / energy loss minimization / energy minimization aspect / food consumption / energy-food-web / consumers receiving food / energy limit / energy surplus / needs/energy / food production / energy intake / energy conversion / example food / energy waste / food web / energy contents / energy containing measure / bio-energy acquisition / food scarcity / human-animal-energy-acquisition / energy losses / energy use / usable energy / food production system / fossil energy / energy limits / energy availability / i.e. energy / food / energy / i . e .ii . e ..i . e .ei . e ..i . e . i . e .ei . e .ni . e .ei . e .ri . e .gi . e .yi . e . / /