The human body is a very Keto 10x complex organism. You must eat the right amount of calories to fuel your daily activity or your body, as clever as it is, will begin to store as many of the calories that you eat as body fat. This is not what you are looking for, unless you see a future in sumo wrestling down the road. So, what really happens when your caloric intake is too low? Your body, going back to the prehistoric days will revert to the flight or fight mode.