Sailing away on a cruise ship with a midnight buffet no longer means waving goodbye to your diet.

Keeping with the times, cruise lines are promising spa-like cuisine alongside the buttery lobster and piles of crab legs. The hope is that lighter selections will lure health-conscious baby boomers and others who fear being trapped at sea with a 24-hour pizza bar.

Royal Caribbean Cruises last year introduced its "Vitality" program, which weaves healthier meals and exercise into the sailing experience. Carnival Corp. now has lighter dishes with nutritional stats on menus for hawk-eyed calorie counters. On Crystal Cruises Inc., fresh fruits and whole grains are playing a bigger role on the buffet line. In the past year, most major cruise lines have tossed trans fats overboard.

"We're hoping it will dispel the myth that a cruise experience is just about overeating. You can eat very healthfully, very creatively, and have a lot of wonderful choices," said Mimi Weisband, a spokeswoman for Crystal.

While cruising is still a small portion of the travel industry, analysts say it's poised to burgeon as legions of baby boomers retire in coming years. But capturing that new wave of cruisers means tuning into their lifestyle, which is increasingly focused on staying fit.

Adopting that good-for-you sensibility on board not only satisfies veteran passengers, but may entice new ones, said Robin Diedrich, a leisure analyst with Edward Jones in St. Louis.

Royal Caribbean in January did away with its midnight buffets.

Providing light, tasty foods is practically mandatory now, but cruise lines are careful not to push them too aggressively.

"They're very conscious of fact that this is a vacation, and it's a time to splurge. People are going to continue to have that high-end lobster too," Diedrich said. "It's not one versus the other."

Judging from the orders so far, not many are exercising their right to eat healthy.

On Carnival Cruises, the "spa" choices only account for about 15 percent to 20 percent of appetizer orders. For main courses, they're only up to 3 percent.