I think the "raw" requirement is the real gotcha here.
You can get plenty of calories from rice and beans. For millenia, the bulk of humanity has lived on really plain foods with little meat (though in some places like europe, north africa, and the middle east, quite a bit of cheese).
Extracting nutrients from uncooked foods is a lot less biochemically efficient for our digestive system, though, and it's going to be the rate-limiting step. If you rule out rice, oatmeal, porridges, bread, tofu, etc... you are likely to be in a mode of basically permanent caloric defect.
A great example is maize. Raw corn is not going to keep you alive for very long. Masa, though, sustains entire civilizations, and it only works because you cook off the meal in high-pH water.
The raw foodies don't rule out grains and pulses. They make them more bioavailable by sprouting them, which uses the enzymes found in the plant itself to convert starches to something more digestible. (Which the plant does anyway in the process of converting its stores to something it can use.) It also makes them softer, so they don't spend quite as much time and effort chewing.
It's still going to be a lot of effort spent eating, and it does seem like they're going for calorie-restricted life extension. But it's not quite as impossible as it sounds, and with a bunch of effort it's actually quite delicious. (And involves at least as much time as cooking.)
It's definitely not my thing, especially since there's so much woo-woo associated with it, but I've had some raw vegan meals and quite enjoyed them. (Omnivory means getting to try everything, which I really like.)
Homo erectus's ability to use cooking to liberate more nutrients from their food was probably a critical factor in the evolution of the huge brains we homo sapiens are able to support.
Calories is not the most important. Vitamins, macronutrients are. You can eat 3kg of sugar, that will count as calories, but 0 macronutrients, 0 vitamins.
You can get plenty of calories from rice and beans. For millenia, the bulk of humanity has lived on really plain foods with little meat (though in some places like europe, north africa, and the middle east, quite a bit of cheese).
Extracting nutrients from uncooked foods is a lot less biochemically efficient for our digestive system, though, and it's going to be the rate-limiting step. If you rule out rice, oatmeal, porridges, bread, tofu, etc... you are likely to be in a mode of basically permanent caloric defect.
A great example is maize. Raw corn is not going to keep you alive for very long. Masa, though, sustains entire civilizations, and it only works because you cook off the meal in high-pH water.