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Sugars: 20g
Notice the sugars part? That's rather high in proportion. The protein is low so it's basically a hunk of sugar with some added carbs (provided by brown rice). The first ingredient on a Power Bar is "High Fructose Corn Syrup". >>
I hate to be a nitpick Andrew, but the reasons Powerbars "work" - if you believe they do - isn't "mostly sugar." Though they do contain high fructose corn syrup and other refined sugars, Powerbars (like other "energy" bars) are typically constituted of a mixture of simple and complex carbohydrates, and the simple carbs (which are identified as "Sugar"

are not what people notice. What people notice is the
carbohydrate total, but not "mainly sugar." To add to that, 20g of "Sugars" is
not a significant amount; you can find 39g of true "sugar" in 12oz of Seven-Up, but you won't notice as much "work" being done as you would with a Powerbar.
You don't necessarily need more protein in a bar for it to be a good workout bar; Powerbars are designed to provide a relatively quick and long-acting (hard to make that balance) energy boost. One of your MetRx bars won't do that any better, as only 50% of calories derived from Protein can be used by the body in a 24hr period. True, MetRx bars will help you to gain weight, specifically muscle, faster when used in conjunction with workouts, but they are no better for long-acting energy supplies.
Rob