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

Cruise lines are now promising spalike 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 Ltd. last year introduced its "Vitality" program, which weaves healthier meals and exercise into the sailing experience. Carnival Cruise Lines, owned by 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 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.

The lighter foods and fitness choices are typically included in the cost of the cruise. On the Disney Cruise Line, that means breakfasts with more whole grains and low-fat yogurts. Crystal is paring down portion sizes and featuring more creative salads. Menus on Carnival cruises list the caloric information for "spa" dishes including: roasted banana panna cotta in citrus broth (150 calories), charred broccoli and cauliflower tortellini (190 calories) or red snapper over stewed fruits (290 calories).

Royal Caribbean in January did away with its midnight buffets, but the famed concept lives on in other ships.

Those looking to get moving on Royal Caribbean ships can consult virtual trainer kiosks and self-guided running maps for land excursions. One class takes passengers on a tour of the ship's eateries, with pointers on the healthiest choices.

For cruise enthusiasts like Linda Coffman, it all means no longer having to worry about gaining weight at sea.

"I always used to try to lose a few pounds in anticipation (of sailing), but I've found that's really not necessary," said Coffman, a 59-year-old travel writer who goes on cruises for both work and pleasure.

While salads and lighter dishes have always been available, Coffman said the variety in choices now is impressive.

The changes come at a time when the cruise industry is seeing steady but modest growth. For 2008, the industry group Cruise Lines International Association projects its members will carry a record 12.8 million passengers worldwide, up from the 12.6 million estimated for 2007.

In 2006, there were 12 million passengers, up from 11.5 million in 2005 and 10.85 million in 2004.

Cruise passengers tend to be older, and many are retired, according to the Cruise Lines International Association. But families, along with baby boomers, are expected to be a big part of the industry's growth spurt in coming years. That means moms and dads fretting over what the kids and grandparents are eating.

And some newer cruises last for several weeks, meaning people are less likely to abandon diets for so long.

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."

Meaning, the virtuous options are only that — options. Food — fatty, high-caloric and lots of it — is still a star on ocean liners.

Whether passengers actually select the lean new plates, just knowing they're available can help drown out second thoughts about boarding what, for many, amounts to a floating binge. Like a gym membership, having a "light" menu might massage away the guilt.

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, said Peter Leypold, the company's corporate executive chef.

Royal Caribbean says it doesn't track usage of its new dishes and classes, but says they're popular.

"That's not to say (passengers) don't indulge. They still love the lobster and a great steak," said Alice Norsworthy, the cruise line's vice president of marketing.

For Coffman, who just returned from a five-day Carnival cruise to the Bahamas, that indulgence is a dessert she allows herself only once every cruise.

"I will not go an entire cruise without having a melting chocolate cake," Coffman said.