There is no known scientific rationale for what you want to happen. Living creatures do not have a "daily caloric requirement." Instead, they maintain their existence by adjusting their caloric output according to what they bring in. If you don't eat enough, you shut down less essential parts. While the US government may recommend 2,000 Calories/day, we can operate on far fewer. As we get near 1,200 Calories/day, our body starts to shift gears to conserve more and more energy. As we approach 500-800 Calories/day, our body will start to shut down bodily functions to preserve energy to support the lower regions of the brain. On the flip side, you have Michael Phelps, who ate 8,000 - 10,000 Calories/day before the Beijing Olympics. There, the vast majority of his caloric intake was expended in his practices.

This flexibility is incredibly important from an evolutionary perspective. Food supplies are never reliable. If you can't scale your output to match your input, you will die and be replaced by a species that can. There is no known species that doesn't engage in this sort of flexible operation. It's fundamental to how life as we know it functions.

To come up with a species that doesn't have this, one is going to have to reach well beyond realistic science. Consider the Octospiders from Clarke's Rendezvous with Rama. That species is a highly advanced species with many peculiar traits. One of them is that they have to be taught to recognize the feeling of hungry. Their babies are born with a truly blank slate, and one of the first tasks of the nursery technicians is to teach the babies to eat before they starve just sitting there.

In such an environment, one might have "daily caloric requirements" in the form of instructions dictated to you. You may consciously be aware of the food you eat and stop when you reach the level dictated by your society.

There is no known scientific rationale for what you want to happen. Living creatures do not have a "daily caloric requirement." Instead, they maintain their existence by adjusting their caloric output according to what they bring in. If you don't eat enough, you shut down less essential parts. While the US government may recommend 2,000 Calories/day, we can operate on far fewer. As we get near 1,200 Calories/day, our body starts to shift gears to conserve more and more energy. As we approach 500-800 Calories/day, our body will start to shut down bodily functions to preserve energy to support the lower regions of the brain. On the flip side, you have Michael Phelps, who ate 8,000 - 10,000 Calories/day before the Beijing Olympics. There, the vast majority of his caloric intake was expended in his practices.

This flexibility is incredibly important from an evolutionary perspective. Food supplies are never reliable. If you can't scale your output to match your input, you will die and be replaced by a species that can. There is no known species that doesn't engage in this sort of flexible operation. It's fundamental to how life as we know it functions.

To come up with a species that doesn't have this, one is going to have to reach well beyond realistic science. Consider the Octospiders from Clarke's Rendezvous with Rama. That species is a highly advanced species with many peculiar traits. One of them is that they have to be taught to recognize the feeling of hungry. Their babies are born with a truly blank slate, and one of the first tasks of the nursery technicians is to teach the babies to eat before they starve just sitting there.

In such an environment, one might have "daily caloric requirements" in the form of instructions dictated to you. You may consciously be aware of the food you eat and stop when you reach the level dictated by your society.