Only small bits of gut-dense fatty protein are required to not only satisfy hunger and burn fat, but also give the brain and heart the ketones it needs as energy. I myself prefer the first method, of eating only once in the day and blissfully flying off to a wonderful no-hunger fast. Fat unleashes lipid mobilizers to burn fat off the body while stimulating glucagon to eliminate all water and salt from the kidneys. Such small bits are required for maximum appetite suppression that we are practically in a fast only punctuated with small gut-dense bites to sustain another day of walking, hunting and gathering. Plant based diets are lacking in sufficient fat for optimal functioning and other cofactors such as B-12.
Energy is stored much more efficiently as fat than as glycogen from carbohydrates.
Animals who get enough fat from veggies are less-active herbivores who need less efficient energy. But Man is an omnivore who, like the carnivore is far more active and needs this more efficient way of storing energy. The synaptic connections in the brain are mostly fat and cannot function well in low fat diets. The studies of David Horrobin shows the improvement of emotional balance and brain function with high-fat diets. The high-fat matrix forces us to see the world and diet in a whole new light.