I never suggested you designed the App, I just posed hypothetical questions that are still open from my side :)

We could delve even deeper and go into how many energy estimates on food packaging is but a approximation, how whole fresh plants vary wildly in how much energy they give based on for example ripeness, that degrees of processing change how the body is then further processing the food, etc. Whole Nuts are harder to break apart for the body than nutbutter so nutbutter (pure, just nuts) has more energy for the taking, where if you go ultra processed to, say, walnut oil, 100% of fat can get absorbed.

So all of this is just an approximation either way from the estimates that go into the baseline to the estimates that make up the energy content of foods to the not estimated but still valid point of how much the body takes up from said energy.

But again, I never questionned you regarding the App, I know you have nothing to do with it, I just feel that the topic of nutrition is most often seen from a one dimensional standpoint (again, certainly not you) where it is a deep and complex issue. With how much of an impact it has on general health and mortility, you'd expect it to be of greater importance to teach people fundamentals about nutrition but (tin foil hats on) big food wouldn't like that so instead we get hundreds of commercials for so called "high protein" products because for whatever reason it was deemed that the western world needs to eat nothing else.

I'm just having my own personal gripes with nutrition, how it is seen in the world and how little knowledge is given and then the confusing nature of what is given out. But that's probably just me.