[fivefifty]

It does make sense if you think about it in terms of overall calories consumed rather than metabolic rate.

Children are very small and light, so even with a higher metabolic rate they need less calories overall than an adult. However a teenager is usually reaching adult size, but still with the same higher metabolic rate as the child, meaning they will need more calories than a typical adult who is on a lower metabolic rate even at similar size, that is why teenager seem to eat so much.

Pregnant women likewise may not have a higher metabolic rate, but they still need to eat more calories overall then before they were pregnant as they are growing in size and weight. It's not much different to a bodybuilder eating more calories to build then maintain a greater muscle mass.