My first cruise was a step-by-step experience.

One flight of steps, the practical ones, invited me with its warm, wall-to-wall carpet.

Another set, powered by a motor and efficiency, guided my legs with rubber foot plates that go nowhere but up and down, up and down.

A third flight - formed of worn, coarse brick - brought me a magical shore-leave moment, accompanied by lizards darting across the fading red and yellow pigmented stone.

Together these steps formed a sort of personal support group on a week-long voyage to explore one widely accepted tenet of vacation travel: "If you go on a cruise, you'll gain weight."

That cruisers likely will add pounds and inches on a cruise is not an unfounded notion. Almost by definition, a cruise is about leisure: Leaving behind telephones, e-mail and household chores.

It's being served meals and drinks (at your table, poolside, a nightclub or in your room). It's being pampered with massages and saunas and facials and pedicures and hair cutting/waving/coloring/styling and aromatherapy and cellulite-reduction treatments and seaweed detoxification sessions.

Nevertheless, it's possible to spend a week doing all a ship offers - eating numerous times a day, sleeping, sunbathing, reading, socializing, gambling, drinking, taking bus tours, enjoying nightclub acts, and indulging in ice-cream snacks and midnight buffets - and still not gain weight.

How so?

For me, it was abiding by two themes prevalent in the health world today:

1. All physical activity - even the seemingly mundane - counts as exercise.

That's where those steps - the literal ones - figured in. Through the exercise they provided, they became my cruising allies: the carpeted steps, connecting the ship's decks; the mechanical ones, driving workouts on the gym's StairMaster machine; and, most fun of all, the ports-of-call steps and hills, including that lizard-lined flight in St. Thomas.

2. The road to well-being is paved with moderation. On a cruise ship, that especially means food and drink.

Moderation wasn't the first thing that came to mind as I explored the Carnival Cruise ship Paradise on that first afternoon, as we began a seven-day loop out of Miami through the Eastern Caribbean. (We would have three full days at sea plus stops in San Juan, Puerto Rico; Virgin Gorda and Tortola in the British Virgin Islands; and St. Thomas in the U.S. Virgin Islands.)

The glitzy, six-story glass-domed atrium, grand columns and classical mahogany and stone architecture set a tone of excess, not temperance, with features harkening to the glamor of ocean liners, from the Queen Mary Lounge to the Rex Dance Club (reminiscent of a famous Italian ship in the 1930s) to the United States Bar (inspired by the passenger liner SS United States).

Unlike the ship, most of the nearly 2,000 passengers tended toward the casual. They spanned all ages, including groups of two and three generations. More than one veteran cruising family brought walkie-talkies to help stay in touch as they roamed the 855-foot-long, 11-deck ship.

Exercise is a moving target

Going into this, I'd had the impression that a week using the fitness facilities on one of these ships was like a post-holiday January at a health club - bustling with good intentions at first, dwindling steadily as days passed and practically deserted by the end.

Perhaps times are changing. Maybe this smoke-free ship (the first, says the cruise line) attracted more health-conscious passengers. Or it might have been just a fluke.

In any case, throughout the week the exercise room looked like many land-based gyms, with rush hours, occasional waits to use the treadmills and otherwise a comfortable, steady flow of guests. There were probably a few more novices than in a typical club, but most looked like they were in comfortable, familiar surroundings.

Which is not to suggest that most or even many guests were regulars. By my reckoning, most Paradise passengers fit more or less into one of six groupings, those who:

-- Don't exercise at all, on board or off, most likely the largest group by far (given typical estimates of the exercising population);

-- Normally exercise and intended to do so during the cruise but didn't, perpetuating the ol' exercise-guilt connection;

-- Used the cruise as a planned rest from ongoing training;

-- Continued their established exercise patterns;

-- Explored the ship's facilities to expand their workouts;

-- Started a new fitness program.

Of all these, the ones most likely to run into trouble - at least in the short term - was that last group.

Few people would admit to trying to get into shape in one week. But admirable intentions, abundant spare time, enthusiastic instructors and enticing classes can conspire to produce another common post-New Year's phenomenon, what might be called "over-eager syndrome." It can produce injuries often nagging enough to nip any new exercise program in the, er, bud for some time to come.

So it went, on our cruise, for Barbara Hannon, 50, of Woodbury, N.J., who went enthusiastically into the first morning's step-aerobics class, hurt her knee, and nearly two months later still was hobbling.

Her husband, Kevin, 50, however, successfully used the cruise to re-ignite his old exercise program. And to Barbara's credit, she continued to come to the Paradise's 12,000-square-foot facility, to enjoy some of the rest of the spa and gym services.

"Just the fact of coming here every morning helps you monitor what's going in your mouth the rest of the day," said Barbara, who helped herself further by drinking plenty of water and avoiding high-fat alcoholic drinks.

Dinner is served

It's common health advice nowadays to take the stairs instead of the elevator, in office and apartment buildings. But that often means passing through closed, fireproof doors to get to cold, drab stairwells with noisy metal steps and questionable security.

On the Paradise, where elevators could be slow and often crowded, the three stairwells linking the decks - conveniently adjacent to the elevator lobbies - were open, roomy, inviting, warmed by carpet and paint. And, quite simply, the quickest, easiest way to get around.

I started most mornings with a trip from my room down a long hallway to the nearest stairwell and up 120 steps to the gym level, working up to tolerably burning thighs and a more-than-slight breathlessness.

From there it was another 16 steps to the top-deck track for a walk or jog. If I was really ambitious I actually started by descending three flights from my deck, adding another 33 steps to the total. (OK, I did that just a couple of times, and that many only because I kept losing count.) I climbed those 120 at least six times in the course of a normal day's activities.

Though it's a good thing some effort is required to get from staterooms and sunbathing decks to dining rooms, that alone probably isn't enough. Unbridled acceptance of all food and drink offered is a surefire way to pack back a few extra pounds.

A rundown of the Paradise's dining features could be mistaken for a dietitian's "How not-to" list:

All you could eat, at every meal. Three multi-course meals each day. Unlimited non-carbonated beverages, notably orange juice, lemonade, fruit punch and sweetened iced tea. Constantly refilled dessert trays, and a seemingly bottomless self-serve soft ice-cream and frozen-yogurt machine. Midnight buffets most nights (sometimes two different ones in a single night), a 24-hour pizzeria and, in case someone got hungry between meals or - horrors! - missed one, 24-hour room service with sandwiches, desserts, fruit and drinks.

Drinks were everywhere, not only in the three restaurants but the nine bars (site of much entertainment and socializing), including poolside, where summer Caribbean heat invited a steady stream of umbrella drinks. The cruising mood was inaugurated with a welcoming Rum Swizzle party in the casino the first night, during which guests over 18 could indulge in the popular sweet libation for 45 minutes - for free.

A semi-saving grace was that espresso concoctions, sodas and alcoholic beverages cost extra, and weren't cheap. The daily poolside Funship Special, usually of the umbrella-drink class served in a kitschy plastic "keeper" glass, was $5.75.

One catch: Drinks were not paid for as consumed but charged to the room via a keycard. This convenience made it unnecessary to carry money, but also allowed passengers to easily disassociate the imbibing from the damage - until the statement arrived the final night. (I was told that on an earlier trip several teenage siblings surprised their father with a soft-drink bill nearly equal to what he paid for the cruise itself. Happy vacation, Dad!)

Although it was possible to choose lower-fat foods in the casual buffet-style restaurant (especially with salads at lunch), many passengers loaded their trays with mounds of meat-and-potato staples and stir-fried specials and happily indulged.

Surprisingly, to me, the formal seated meals - which I'd thought might be dominated by heavy entrees and rich sauces - had the most potential for varied, healthful eating, with as much attention to presentation as portion: a cool gazpacho, a few artfully arranged baby carrots and squash.

"I try to stay away from the buffets," said Tom Sanchez, 47, of Belen, N.M. "I do the (dining-room) seatings, have fruit in the mornings, and try to stay away from dessert."

Each dinner menu included several choices among appetizers, soups and salads, entrees and desserts, and also noted which were "spa" items, which meant lower in fat, sodium and cholesterol.

Low-fat is relative, however. When the spa-menu quail entree was listed as having 32 grams of fat per serving, I could only imagine how many were in the rest of the entrees. (In a typical 2,000-calorie diet, the American Heart Association recommendation of no more than 30 percent of calories from fat equates to 66 grams per day.)

Perhaps more significantly, the atmosphere at those seated meals also contributed to a more attentive, deliberate approach to eating. Being assigned to tables of eight to 10 meant dusting off manners not always used in drive-throughs, pizza parlors or even at home.

The art of conversation took at least some of the focus off food, even when the discussion was about that food. At the very least, being surrounded by acquaintances of only a day or two tended to curtail the urge to chow down and rush back out into the sun.

(An emphasis on manners seemed to be subtly continued in the films offered on the in-cabin televisions: "Pleasantville," "Blast from the Past" and - the one that gets my vote as gutsiest movie to show during a cruise - "Titanic." )

And, frankly, though I'm always game for good, plentiful food, I wasn't overly enticed by either the casual or formal dining fare. Unaccustomed to consistent heat and humidity, I felt like eating lightly throughout the day. That in turn made me more inclined to work out. And, perhaps spoiled by the quality and variety in restaurants today, I found the ship's buffet food OK but predictable and the dining-room menus finer yet not extraordinary - which wasn't surprising, considering they're serving up to 650 people in each of two dining rooms at about the same time each evening.

Workouts, workouts everywhere

Like most large cruise ships, the Paradise featured an exercise room on the sports deck, just below the top sun deck. Equipment was at least comparable to a medium-size, mid-range health club, including strength and cardiovascular machines (treadmills, stationary bicycles, stairclimbers, rowers) plus sauna, whirlpool and steam room.

The small free-weights corner looked to be mostly the domain of veteran lifters, though a few teenage boys swaggered over to swing around more weight than they could handle. The Kaiser strength-building machines seemed to be the least used, a pity since they offer easy, controlled movements, adjusted resistance with the push of a thumb - and count repetitions to boot.

For those continuing their regular fitness program, the cruise opened the door for improved workouts.

On her way up to the gym wearing telltale weightlifting gloves, Brenda McCullough, 50, said that being away from the stress of her property-management job in Memphis actually helped her daily exercise routine.

"I'm able to rest and get better workouts," she said. She spends 45 minutes lifting weights, one body part per day and each muscle group not more than once a week. This day, she would work her legs. She also does 30 to 40 minutes of cardio work three times a week, and has stuck with such a program for 15 years.

`It's what keeps me sane," she said.

She handled the food issue simply, sticking with, for example, egg-substitute omelets with lean ham, and fruit, fish and chicken.

As in most fitness clubs, the treadmills were the machines of choice, often with one or two people waiting. The view out the large windows was at least as interesting as most television programs.

The ship's gentle side-to-side rocking, usually imperceptible, became more apparent when I was on a treadmill. Even more fun was watching the waves while using the Concept II ergometer, imagining I was rowing through the Caribbean.

The ship's two pools were, regrettably, not for lap swimming but for lounging and catching children using the spiraling water slide.

Exercise classes - aerobics, strength and conditioning, stretching, and fitness and nutrition seminars - were complimentary; personal-training sessions cost $45 and body-composition analysis $15. Trainers could set in motion customized programs, emphasizing stress reduction, stretches and exercises for back pain, or weight-training at home, with the potential for lasting impact.

Mary Balasi, 51, learned in her personal-training session that she had difficulty losing weight because she didn't have enough muscle mass (to speed up her metabolism). So she began a strength-training program on the ship, getting to the gym by 6 a.m. - "I can't deal with the crowds" - and learning how to use free weights and a step bench. When she got home to Gloucester Township, N.J., she bought some weights and joined a local gym.

Most of the other fitness services offered (also for a fee), leaned in the spa direction: massage, aromatherapy, electrode-and-seaweed-lotion sessions aimed at "correcting" cellulite, and assorted other skin and beauty treatments. All were rightfully in the realm of pampering, but not fitness.

Workouts could be found elsewhere. Just strolling anywhere on the ship was persistent, gentle exercise to improve balance and stability. The top-deck "Olympic" eighth-of-a-mile track provided panoramic views yet sometimes too much wind for a normal gait.

Simply walking between ship activities could accumulate a few miles a day, and some adults counted on burning calories each evening dancing in nightclubs.

It was even possible to exercise while gambling. Two Pedal & Play slot machines on a covered open-air deck overlooking the pool offered stationary-bicycle rides while feeding quarters into slot machines.

I saw only a handful of people try it, and I'd wager neither serious gamblers nor serious exercisers would be caught near them.

Pounds and sense

Stops at ports offered plentiful workouts, though most passengers gravitated toward bus tours, sunbathing and not-so-vigorous snorkeling. I found stair or hill workouts at each (see story on page XXXXX) that not only added to the day's exercise but also to a more visceral experience of place. One was at a San Juan park whose grounds, trees and cave-like pockets in a crumbling old wall were teeming with so many pigeons the very air seemed alive.

Back home, after all those climbs on and off the ship, I noticed a significant improvement in my fitness on the waterfront steps I like to climb occasionally. Before the cruise I struggled to stay on them for 20 minutes or so; right afterward, I could handle 30 minutes or more.

Nutrition-wise, I was far from strict throughout the week - want some tips on soft-ice-cream-cone swirling? - yet I didn't gain any weight.

Though not inevitable, putting on pounds during a cruise is clearly possible, and certainly understandable.

I'd suspect, though, that whatever eating or exercise issues contributing to unwanted weight gain on a cruise don't develop on the ship and don't disappear upon leaving. Which wouldn't have been good news for the rather subdued couple sitting on those nice carpeted steps on the next-to-last day of the cruise.

"Every day I say I'm not going to eat so much today," she told her partner. "Fortunately, we're almost through. That'll put an end to it."

Molly Martin's column on fitness is published weekly in the Seattle Times' Pacific Northwest magazine.