This is a tough question and I have asked myself the same many times. There are so many variables to consider: location, season, epoch. For example people in the humid tropics were probably able to get fruits and large insects on a regular basis. My guess is they would have been able to eat much more often. I would think those that hunted large game would have an initial kill, have their fill, and consume the carcass over the next few days eating as they were hungry but maybe not necessarily gorging themselves. Maybe they would save some of the fatty portions for later, or maybe they just ate everything right there and went back on the hunt. Perhaps eating very little for a couple days. But then again, they were probably smart enough to know when they or their kids would be getting hungry again before hunger actually set in. If it was me, I might be a bit proactive about that b/c I don't like going to sleep hungry.
But remember, we have amazingly capable bodies that can go without food for long periods of time. That didn't happen just overnight. Humans and our ancestors must have gone through long periods of time, perhaps epochs, multiple times for this sort of thing to develop. Think of when a metor strikes the ground, a massive volcano erupts, a plague strikes, climate change, etc. These things can cause resources to become scarce for long periods of time. It is only the tiniest fraction of life that has ever existed that has survived to the present.
And in all likelyhood, scarce food and toxins probably change gene expression as generations progress, without necessarily changing the genes themselves - I have heard that posited on this forum. I do know that children don't develop as well with not enough food. So we can survive without as much and continue the species, but it surely has killed off a large number of proto-humans who were not as fit for survival. Even the ones that survived terrible disasters and shortages of food probably lived shorter lives and were not as strong or smart as they could have been on full bellies - tho still the most resilient of their species.
Which brings me to another idea. We often wonder at how our brain size increased so quickly in the paleolithic. By all accounts it appears to be quite a rapid evolution.
Perhaps this period, this epoch, was characterized or preceded by another in which our ancestors and many other lines that did not continue, were under incredible hardship. With barely enough food to survive and perhaps toxins often in the air - maybe a period of greatly increased tectonic/volcanic activity spewing much ash. Perhaps a change in the protective fields surrounding the earth shielding us from many of the suns harmful rays?
But perhaps this period killed off a great many hominids and life in general, leaving few resources, and presenting an environment that promoted genetic mutation. Only the strongest, most capable, and in our case, INTELLIGENT, of these survived. There is evidence in our mitochondria that our race was at one time whittled down to just a few thousand, though I don't know when this occurred. At any rate, those that did survive would be quite hindered in their full capability to develop; that is, a full expression of their genes; but, their genes would have the greatest capability of expression once life recovered and presented a less challenging place to survive.
And perhaps thats is exactly what happened, in what seems like a very short period of time. As the earth returned to a more suitable place for life, and we had much better nutrition, our bodies and genes were more fully capable of expressing the full strength and intellect that could not be expressed earlier due to conditions.
In all likelyhood, everyone's ancestors had generations of plentiful food where we ate alot, and other generations where we would have been forced to fast. So do what feels best and gives you the best results. I'm sure your body can adapt to whatever eating scheme you throw at it, but realize it might not be a good idea to go too far to the extreme in either direction.
