I agree, it depends on the definition of the spectrum or range of values that would then provide a definition of balance. Maybe the food groups could be the lev

I agree, it depends on the definition of the spectrum or range of values that would then provide a definition of balance. Maybe the food groups could be the level at which this is defined, so too much or too little of one food group is probably not good. A good example is the meat-only diet that became a recent fad. People can claim all kinds of benefits there but in the long run it's just not balanced, and we're not built like apex predators in nature.