The name comes from the word "hooah", an expression of high morale, strength and confidence. Commonly used by American soldiers, Marines tend to prefer the word "Oohrah!" on the packaging. The bar originally had "HOOAH!" and the US Army seal on one side and "OOH-RAH!" and the US Marine Corps seal on the other; newer wrappers had both logos on the same side. The commercial version features the United States roundel instead.
The original military HOOAH! Bar came in apple-cinnamon, chocolate, raspberry, cran-raspberry, and peanut butter flavors. The smaller First Strike bars (provided in the concentrated First Strike Ration) come in the same flavors, except peanut butter; mocha is used instead.
In 2004, D'Andrea Brothers LLC licensed "HOOAH!" for commercial sales, and the company started marketing the bar to the public in 2004. The energy bar is now named "Soldier Fuel" instead of HOOAH!, and provides 270 to 280 calories, 10 grams of protein, 8 or 9 grams of fat and 40 grams to 42 grams of carbohydrates.