To clarify, soy is a complete protein. What I meant was that the levels of BCAAs in soy are relatively low - especially when only taking in ~80g of total protein / day as the recipe suggests. This is why many longterm vegetarians/vegans often still have to supplement, dispite a high-soy diet. Soy protein is composed of about 18% BCAAs and is fast to metabolise, especially when isolated and diluted in liquid. Furthermore, without solid food in your stomach, certain enzymes are never released by your body's GI so metabolism is left almost entirely to your kidneys.