One possibility for the future is mapping your internal chemistry and having it analyzed with a massive database to see what foods work best for you. Another may involve tweaking your gut microbiome to change how you extract energy from certain foods.
1) Eat food - food does not list ingredients, but often is listed as an ingredient. A potato is food, A box of scallop potatoes is not. If what you are eating is required to have labels to inform you of what is really in it, then it isn't food. (Note: this applies mainly to packaged food products. Obviously, there are foods that have labels, because they may be packed in water, etc.)
2) Don't change calories - Calories simply measure the maximum amount of energy that may be utilized. People have different metabolisms so that one person may be more efficient at utilizing those calories than somebody else, but that doesn't mean we should change the measure. Different automobiles are more or less efficient at utilizing gasoline, but that doesn't mean we should change how gasoline is labeled.
3) Calories aren't nutrition - Calories are about energy, not nutrition. 100 calorie apple and a 100 calories of sugar both provide the same amount of available energy, but the sugar has zero nutritional value. However, since calories do impact weight as in calories consumed less calories burned will either add to or subtract from one's weight, they can't be ignored. On the otherhand, they shouldn't be obsessed over, particularly since metabolism has a major impact on weight.
4) CICO - Calories In, Calories Out - assuming one is getting adequate nutrition, if the concern is weight, then regardless of ones metabolism, if you are gaining weight more weight than you want, you either a) need to reduce calories or b) burn more calories. Likewise, if you are losing more weight than desired, you need to a) increase calories or b) burn less of them. It doesn't take some database tailored to your specific body or specific flora in your gut. Those may explain why one person loses or gains more than another, but it doesn't alter CICO.
TL;DR - We don't need a national database of each person's metabolic profile or gut flora. We simply need to eat nutritious food and have more active lifestyles.