For those watching calories...

I subscribe to the RSS feed for the Nutrition Data blog. Today's post is striking to me. It's really a reiteration of an article from Marion Nestle.  The first thing that strikes hard:

Here’s the deal on food composition tables: you have to consider these numbers as ballpark figures, not as something engraved in stone.

That's not really too shocking. Food science has never been an exact science. I understand that intellectually. I think I fail to grasp the concept emotionally though.  That's when I saw this:

A 50-gram hard-cooked egg is 78 calories? Plus or minus 10 maybe.

Sure, it's 10 calories; but if it's 10 here and 5 there and 10 over there, that's 25 calories extra that I am eating and may not know it. The other thing that whacks me hard in the gut:

...food companies know quite well what is in their products but they won’t give the USDA any information about nutrient composition beyond what is on the food label; they consider that information “proprietary” and don’t have to.

It seems so useless when reading this article. Why bother when the data we do have is circumspect (despite the very best efforts); and companies want to keep it that way?  Dr. Nestle says:

I use the USDA figures as ballpark estimates and don’t pay any attention to small differences.

I wonder what "small differences" mean to her.  Maybe I'm just tired of fighting a battle that has more obstacles than I have ideas.  Does this mean "counting calories" is really about consistency?  If it is, what does that really mean for the concept of move more + eat less = weight loss?  How can you trust that you are eating less when your morning hard boiled egg could be 68 to 88 calories?  This makes my brain hurt.