Calories as the basis for weight gain/loss is genuinely absurd. It's based on a naive interpretation of First and Second Laws. A much more appropriate unit of measure would be something like a dose-to-mass cause/effect ratio of a particular substance. We have ample precedent for such a unit of measure with a multitude of drugs and other substances which have a direct effect on body mass (both fat and lean mass) independently of food intake and physical activity.

Consider growth hormone for example. Compared to food, the total mass of HGH is insignificant (therefore the total caloric content of HGH), yet its effect on both fat and lean mass is several orders of magnitude greater. In this case, dose-to-mass cause/effect ratio as a unit of measure is a no brainer. If there's still any doubt about the validity of comparing HGH to food with regards to caloric content, consider that HGH is a peptide hormone - it's a protein. In spite of HGH being a protein, in spite of protein being a calorific macronutrient, nowhere on this planet do any of us consider the caloric content of HGH for any purpose whatsoever ever. The same argument can be made for insulin, testosterone, estrogen, T3/T4, you name it.

Based on the above, and based on the unarguable fact that different macronutrients have different effects on fat and lean mass, the same unit of measure for something like dose-to-mass cause/effect ratio is also a no brainer.

Once we've determined an appropriate scale for various foods and meals and such, then putting up that unit of measure on restaurant meals becomes genuinely useful. Otherwise, the calorie is a total waste of grey matter.