At Slate, Kate Greene writes that in her experimental work on a NASA-funded research project, she found that women would be cheaper to fly to Mars than men.
She writes that it is due to metabolics and average body mass. On a mock mission in Hawaii, Greene found that women burned "less than half!" of the calories that men did; this meant they consumed less food. Less food required would decrease the cost required in fuel expenditure as well as the ultimate weight of the rocket.
While Greene found that a handful of NASA experts agreed a small, all-female crew could be beneficial, she ultimately lands on the notion that diversity is best. Greene interviewed one, small female astronaut: So-yeon Yi of South Korea, who is 5'4". Yi said larger astronauts were envious of the relative ease and comfort she had in the space station. She also confirms, though, she would rather be around a group of people more diverse than everyone who was just small and relatively comfy and cheaper to fly into endless space.