An interesting topic to me.
I am wondering if we are talking about two types of measurement error:
I believe that we have both sources of error in calorie counting. In the case of Soylent the company that provides the calories per unit could provide a biased number (e.g. consistently off by 10 kcal/100 grams). However I could introduce random variations by inaccurately measuring my daily portions.
We know for a fact that the published calories on food have inaccuracies. Most calorie estimates are based on the Atwater system
According to the National Data Lab (NDL), most of the calorie values in the USDA and industry food tables are based on an indirect calorie estimation made using the so-called Atwater system. In this system, calories are not determined directly by burning the foods. Instead, the total caloric value is calculated by adding up the calories provided by the energy-containing nutrients: protein, carbohydrate, fat and alcohol.
But we know these measurements have inaccuracies.
So we have biased estimates. And we have random error. I think the random error due to my measurement error is likely to end up being normally distributed as has been argued.
I think of calorie counting as a system that "approximates" calorie intake subject to both systemic and random error. And don't forget to add in error in the critically important estimates of basal metabolism rate and calories burned in exercise. My various exercise monitoring applications / devices give me substantially different calorie estimates and the ones that are "built into" the apps like Fooducate and MyFitnessPal no longer are even within 50% of my heart rate based estimates as I have gotten more fit.
Therefore I juggle my goal calories to get the outcome I want.