Before 1970, when a more nourishing diet was still keeping our ancient five-part appetite-control system fully functional, we enjoyed our healthful diets. But now, the average American diet is estimated to be 60 percent nutritionally void. As our diet has become less nutritious, critical brain functions have become weakened, making the lure of druglike commercial foods even stronger. Notably, since the 1970s, our intake of protein, with its 20 vital amino acid constituents, has dropped by a hefty one-third. Here’s one example of the consequences: When recovered bingers are given a diet lacking in just one amino acid called tryptophan, for just 24 hours, their brain levels of the appetite-regulating giant serotonin plummet, triggering an immediate resumption of bingeing.