The problem with this though is that dwarves will need to eat seven times as much. It's more realistic, but seven times as much. Seven times as much. That's a lot. That is a whole lot more food you're going to need. Just imagine the current amount of food you need for fortresses, then multiply it by seven. As it is you can easily end up running out of food early on in fortresses, but with this change you'd need to start calculating how efficient bringing animals and butchering them is on food for embark points compared to bringing food, only bringing one copper pickaxe and no axe to buy more food, and bring two proficient herbalists in order to even start a fortress. I think the best way to implement more food production difficulty is by adding in food spoilage, which I think there was a really good suggestion thread about pretty recently. because food spoilage means that you can have enough food early game, and you'll probably be able to feed dwarves in an emergency, but you'll need to put in more work if you want to export only food or survive a siege without any internal food production.
If we just add in food spoilage all that will happen is we end up with vast mountains of rotting food because the present food production rates are so much higher than food consumption rates such that the only way to avoid mountains of rotting food would be to export it, simply in order so it can rot away somewhere else; thus the economic madness of trade as it present stands.
Fool spoilage requires increased nutrional requirements to exist, not the other way around. Eating seven time as much would not be unmanagable, it would just mean that we would have to expend a greater amount of labour time fishing, gathering, hunting and farming. In most biomes there are plants just waiting to be picked and eaten, early in the game herbalism may well be an option, if you start near a river then you can fish, otherwise you can generally hunt down animals.
Nutrition is based on many factors, including size, activity level, and efficiency of the digestive system.
How about making nutritional needs raw defined? Each creature could have a value for how much their food and drink counters lower per frame. Also, each material could have a value determining how filling it is, with separate values for food and drink. A single nut should not fill you up as much as a whole watermelon, and fruit could contain some water which reduces thirst when eaten. This would make a lot more sense than the current grazing system.
Actually I would rather keep it simple at 1 food unit per eating unit. That is because units of food are sort of arbitery anyway, so 1 unit of meat can easily contain as much calories as 1 unit of fruit, but in reality there are far more fruits in a fruit unit than meat in a meat unit.
I would not object to bieng able to put a raw modifier into the system to adjust the food requirements of a creature by a certain amount. The default amount should be what you are working on and you then adjust the amount using a custom tag. The idea of having fruit count as drink is a pretty good one as well, we can make it work backwards from the drinks count as food.
So if a dwarf eat 4 units of fruit then he has to drink one less unit of drinks at his next drinking session.