Well, if there was an inventory penalty for staple foods to counterbalance their easy access, you might rebalance it with basic food taking much space and giving few bonus.
There are both weight and container rules in the game, but all weights are realistic. The game has an emphasis on realism, its really a simulator - like a flight sim - except you control a human during the Paleolithic era, instead of an F-22 Raptor or whatever.
So i can't jing the weights or space required by foods. Fact is you can live a long time on a backpack full of nuts. Just one jar of peanut butter is close to 2000 calories - more than 3/4ths of a days worth of food. And a backpack full of rice - you have a couple weeks, if not a month's worth of food.
When it comes to balancing, games where you make up the rules and sims where you don't are a bit different. With sims, its all about accuracy, and let the chips fall where they may.
So all I have to work with are the incentives and disincentives you would have in the real world for not eating the same food all the time. Things like you get sick and tired of it, and it may not be a balanced diet, leading to malnutrition.