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 Ltd. 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.

Though 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 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 for 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.

For cruise enthusiasts such as 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 Ms. Coffman, a 59-year-old travel writer who goes on cruises for work and pleasure.

While salads and lighter dishes have always been available, Ms. 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.