There is a saying that A pint's a pound the world around.. There are 2 pints in a quart and 4 quarts in a gallon (check the supermarket dairy shelves). Therefore, a gallon of water weighs 8 pounds and 5 gallons weigh forty pounds.To lose one pound by weight reduction, you must lose a pint (or pound) of flesh or excess liquids.Losing forty pounds is like losing 5 gallons of flesh!Kes · 9 years ago.herefore, a gallon of water weighs 8 pounds and 5 gallons weigh forty pounds. To lose one pound by weight reduction, you must lose a pint (or pound) of flesh or excess liquids. Losing forty pounds is like losing 5 gallons of flesh! Kes · 9 years ago.