Inside a tiny trailer outside the Fort Avenue Merritt Athletic Club, a 56-year-old chief financial officer stripped, down to a spandex swimsuit.
Out of his office uniform — tweed jacket, jeans — Sam Ulan strapped on a blue swimming cap and climbed onto what looked like an arcade space shuttle.
If he looked like a trapped polar bear inside the contraption, he was doing it for a good reason.
He was getting his body fat measured.
"I'm getting on in years and I'm trying to reach an ideal weight to avoid health problems," he said.
Ulan's been on a tear to lose weight since the beginning of the year, and he's been using this machine, called the Bod Pod, to track his progress.
It used to be your bathroom scale was the way to do this. If you wanted to get clinical about it, your doctor might have used skinfold calipers to measure excess fat.
But Americans' increasing preoccupation with their weight has led them to seek even more detailed information about their bodies.
In doing so, they've atomized a whole industry of devices to help measure, to the gram, how fat they are and in what ways. It's not just calipers, now there are body scans, electronic sensors, underwater scales, even fancier bathroom scales that come with fat percentage monitors.
In 2007, 436,000 scales that measure body fat were sold, up from 316,000 three years before, according to market research firm NPD group.
The Bod Pod is just the latest fat meter out there, and is said to be the most accurate. Just this year, it started being used by Maryland gyms like Brick Bodies and Merritt Athletic Clubs.
But the question before these devices is not how accurate they are, but if the information they pop out as easily as Pez dispensers is even useful for the general public.
For some dieticians, these devices only encourage dieters to treat their bodies like ledgers, and may cost them more than just sensible eating and exercising.
"We're too focused on numbers," said Jane Jakubczak, coordinator of nutrition services at the University of Maryland. "People want to come back every week and see a change in their weight. They want to measure their progress. The problem is that body composition changes very slowly. Unless they're looking at a year-long fitness regiment, I don't know how helpful these devices are."
For years, the body mass index was the standard for determining if you were over or underweight. But in the last decade, Jakubczak notes, people have learned that it's not just important to look at body fat, but at the kind of fat they possess.
"BMI just takes your body weight and height and puts it through an equation to come up with a number," she said. "It can't measure body fat percentage. You have to measure it through these machines," Jakubczak said.
Out went your bathroom scale, and in came the futuristic fat meter.
The Bod Pod has been in use for a decade. But it's been in Maryland only since July 2008, when Matt Bender, a former Navy radar tech, bought his own franchise and mounted it on a trailer truck.
He travels to Maryland, Virginia, Delaware and Pennsylvania gyms in a tiny camper that gleams like a hubcap and bears a simple sign that reads: Be Fit-Test.
The pod, which looks like a toy rocket, the type you'd see at malls or arcade, calculates the amount of air that's displaced by the subject inside, and spits out all sorts of factoids: fat mass, lean mass, even thoracid gas volume.
Its computerized scale is so precise it's used by the Cleveland Browns and the Oakland Raiders. Dwight Galt, the University of Maryland Athletics strength and conditioning coach, has used it on his students.
Kelly Whalen, a Merritt district personal training manager, said they offer the service because it's more accurate than the caliper or the electronic censors, called bioelectric impedance.
Less than two minutes inside costs $45; $75 for two sessions. But despite the cost, it's resonated with Merritt's clients. Though in January only 10 used it in one day, now they're averaging seven an hour, Whalen said.
Ulan has strapped on the spandex to use the pod four times already. When he started dieting earlier this year, he lost weight, but the machine told him he was actually losing more muscle mass than fat. Calipers wouldn't have gotten that specific.
"If you do calipers on me, they'll say I've got 14 percent body fat because my legs and arms are really toned," he said. "But it's really more like 27.5 percent. They make me feel good, but they give me an inaccurate picture."
But he said this kind of granular information is more helpful to serious recreational athletes like himself — he's a marathon cyclist — because it helps them craft fitness plans that are more sophisticated than those of the typical dieter.
At Merritt, Brick Bodies and the University of Maryland's Health Center, electronic meters, calipers and old-fashioned scales, as well as physical assessments by trainers are all offered for those trying to lose weight.
But it's the fast-food approach of these devices and the emphasis on cold numbers that worries a dietician like Jakubczak. At the University Health Center, she doesn't weigh her patients unless they ask.
"The problem with numbers is that they don't come down quick enough and people get very frustrated. They see that they lost 2 pounds instead of 5 and they throw their hands in the air and give up," she said.
Instead of focusing on numbers, she interviews new patients on exercise and dietary behavior, and from that, she develops a meal plan to go along with exercise.
If they're goal-oriented, she directs them to different figures, like keeping tab of how many times a day they eat fruit, how many times a week they have breakfast, or if they've cut down on the number of sodas they have.
That's because gauging their progress by tracking their weight as if it were the stock market is one battle they won't win.
"We just haven't found a really cheap, easy way of measuring this," she said.
Body Mass Index: An equation that uses height and weight to calculate body fat. Pro: Free. Con: Inaccurate; it doesn't distinguish between body fat and lean muscle mass.
Skinfold Caliper: A two-prong tool that measures love-handle size. Pro: Widely available at doctors' offices and gyms. Con: Broad strokes results; can be inaccurate if administered incorrectly.
Underwater scale: Measures the ratio of mass to body volume. Pro: dietician Jane Jakubczak calls it the gold standard of fat meters. Con: inconvenient, time-consuming and costly, starting at $200.
Bioelectric Impedance: A device that sends electrical currents through body. Pro: Portable, easy to use, and affordable; $30 at Wal-Mart. Con: Average accuracy.
Bod Pod: measures body fat percentage by calculating air displacement. Pro: 1-2 percent margin of error. Con: Cost, starting at $45 per minute-long session