I purchased this product after trying the Original Unflavored, not for the "lean" aspect but for the additional food sources. With the Original, I noticed that my hair and nails were growing at a much faster rate and my skin had fewer blemishes and looked healthier and more supple. I figured the Lean would be even more beneficial with the added food sources and higher amounts of amino acids. I put a scoop in my morning coffee. I LOVE the flavor. I have not put it in shakes or smoothies, but I am sure it would be just as tasty. Since using it for a few months, I have noticed digestive and joint benefits in addition to the abovementioned benefits from the Original. I can't confirm (or deny) any metabolic benefits as I did not purchase the product for this purpose and have not measured them since taking it, but I suspect positive impacts as I have noticed digestive benefits. I have always had paper-thin nails (and baby-fine hair). Nothing has every made my nails stronger, but they have been growing like happy and healthy weeds (along with my hair). I have tons of new growth and my hair is fuller due to volume. I use both the Original Unflavored Lean on a regular basis. They are staples in my diet.