You can survive on rice alone for some time. Brown rice is much healthier than the well-known white rice, but both have no vitamin C, which leads to scortbut disease. The performance of the brain would also no longer be fully functional. You could only survive more or less healthy for about 2 months on rice.
Oh well. But somehow it has to work?
Perhaps you are now thinking that you might want to try rice as diet. And you are actually not the only one. Many people in Nepal eat brown rice every day, even if they also cut vegetables with the rice. And yes, it is actually a balanced diet. However, eating only white or brown rice is not a good idea, which I would like to explain in the following text.
First of all, how much vitamin C does rice contain? I agree! 0! The Disease Associated With It called Scurvy, which was only discovered in the 1930s, will definitely not make your life easier, while suffering from muscle weakness, bleeding and inflamed gums. The white rice simply lacks fiber and minerals. The brown rice is a bit better, but the vitamins are also missing there.
You wouldn’t get fats and proteins well from a “rice diet” either. These are important for the proper functioning of your muscles or for your brain to function properly. Eating only rice would actually prevent you from thinking in the long term.
You have to look at it realistically here. In the first few days, it would probably not be a problem to only eat rice. But just imagine you eat rice for a WEEK in the morning, at noon, in the evening. At some point this stuff would hang out in your throat and you would probably never touch it again afterwards.
To survive alone on a desert island, rice is arguably one of the best choices you could make (if you had a choice at all) but it’s hardly difficult to imagine the experience of diet or the struggle for survival on an island , wouldn’t harm your relationship with rice in the long term. You would most probably never touch rice agian, which is a shame, because of the endless possibilities that are possible with it!