At first glance, Moonlight Basin, Montana, wears a sleepy smile with its skein of lazy, near-empty blue runs, but beware: That soporific grin hides fangs. Just look up—way up—to the Headwaters, a snarl of a headwall that's striped with a dozen lift-served

Easiest Diet Ever

Good News: Going from sea level to 5,000 feet and above spurs your metabolism to burn an extra 300 calories a day, reports Monique Ryan in Performance Nutrition for Winter Sports ($20; Peak Sports Press). Bad News: Until you acclimatize, a diminished appetite may cause you to undereat, resulting in less energy when you need it most.

chutes that can tip 50 degrees or more in spots. Whether you're a snow bunny or a sick bird, though, Moonlight offers the best of both worlds. When the lifts close, head to the lodge, a grand timber-and-stone palace anchored by a central fireplace so lofty that stuffed mountain goats pose on its rocky chimney. And there's more: Moonlight and neighbor Big Sky Resort have stopped their Cold War–like bickering and wisely joined forces. Buy the Lone Peak ticket this winter and ski a linked, Euro-style spraddle of 5,300 acres. Ah, the fruits of détente. Moonlight (full-day adult), $40; Lone Peak (full-day adult), $78; 877-822-0430, www.moonlightbasin.com