why is a proper meal called a square meal?

a square meal dates to 1868 although it did not become common until around 1880. of american origin it comes from the adjectival use of square to mean sturdy or substantial. there are older related senses of the adjective square . inthe 17 th century square was used to describe someone who could eat and drink copios amounts. the style of eating dubbed square meal, where eating utensile must be moved at right angles and is a derivative of the common usage.not the origin.