Carnivorous describes organisms that eat meat. The term applies chiefly to animals whose diet is based on animal flesh, from lions to insect-eating shrews, and also to plants such as the Venus flytrap and pitcher plants that trap and digest insects to supplement the poor nutrients of their habitats. In human dietary discussion it describes meat-centred eating patterns, sometimes adopted for perceived health or simplicity reasons. Nutrition science notes that while meat supplies complete protein and key micronutrients, diets excluding all plant foods lack fibre and many protective compounds, and evidence favours varied diets. The ecological cost of carnivorous human diets is also considerable.