What is the origin of the idiom "square meal" and when to use it?

The origin of the idiom "square meal" can be traced back to the maritime and nautical culture of the 18th and 19th centuries. Sailors and seafarers often ate their meals off square wooden plates, which were sturdy and did not easily tip over in rough seas. These meals were substantial and balanced, typically consisting of a hearty portion of meat or protein, vegetables, and bread, providing the sailors with the nourishment they needed for their demanding work. Over time, "square meal" came to represent a well-balanced and satisfying meal.