(Bloomberg) — In the fitness centerat an investment management firm, ChrisSerrano swipes cold goo across my stomach and wavesan ultrasound wand. He’s about to perform a test “very similarto what they would do if you were pregnant,” he explains, only thisone will measure, to the nearest tenth of apercentage point, just how much of my body is fat.

Already he’s grilled me on my health: How many glasses of waterdo I drink each day? (Not enough.) Can I namethree foods with omega-3 fatty acids? (Apparently not; Ithought broccoli had all the nutrients.) Next, he’ll have medo lunges, squats, leg lifts and side planks that willreveal, unsurprisingly, that my core and hips are weak. (Hisprescription: Work out more.)

Serrano, a former college footballplayer-turned-fitness trainer, is one of the key perks ofworking at FS Investments. He’s also one of the very first peoplenew recruits meet when they start. Their meetings with him, atwhich they, too, will get their bodies and exercise analyzed, arejust phase one in the company’s elaborate,all-encompassing employee-wellness program.

Related: Wellnessprograms on the rise as employers consider more thanROI

That program, dubbed “the Journey,” was custom-made for FSby Exos, a pro-athlete training center turnedcorporate-wellness business. At other companies, suchas Google or Intel Corp., Exos might outfit a fitnesscenter or offer nutrition consultations. But at FS Investments,whose program goes far beyond any othersExos offers, the perks—free meals, gym, workoutclasses, personal trainers, nutritionists—permeate even the mostmundane details of nearly all its employees’ everydaylives.

The corporate-wellness business — fromonce-a-year biometric screenings to all-encompassing programs suchas the one FS offers — has ballooned to a $6.8 billionindustry, according to IBISWorld analyst Kelsey Oliver, all on thepromise of reducing employers’ health insurancecosts. Employers pour money into such initiatives — notthat they have much to show forit. Multiple studies (PDF) by the RANDCorp. have found that such programs don’t save companiesas much money on health care as they cost — even when lots ofemployees participate, which they generally don’t do.After all, the medical events, like heart attacks, that costemployers so much aren’t so easily prevented. “The link betweenyour behavior and the costly events is way too weak to ever make abusiness case,” Soeren Mattke, an author of the RAND studies,says in an interview. “It is extremely hard to reduce costs bychanging behaviors.”

Despite such evidence, many employers still believe in thepower of wellness programs and are trying to get moreemployees on board. Many turn to such incentivesas prizes or gift cards. Others threaten fees fornot participating. FS Investments, however, doesn’t reallygive employees a choice. Sure, the moderatelyinvasive consult with Serrano is technically optional,but it’s required for employees to get on the meal plan — and who’sgoing to turn down endless free food?

As a result, FS Investments’s has unheard-of participationrates. Almost everybody eats the free meals (those I speak with rave aboutthem), and around three-quarters of the Philadelphia-basedcompany’s 330-odd employees participate in the on-site fitnessprograms, which range from yoga to weight-training to a walkingclub. The gym, open 24/7, offers morning, evening,and mid-day classes; sometimes whole teams leave their desks to gowork out together. Around two dozen people are in the 7:30a.m. weight-training class I attend.

The cafeteria offers healthy options for breakfast, lunch,and — for employees who work late — dinner. Each meal isportioned out by “zones” determined by Serrano and staffdietician Becki Rabena; people in Zone 1 get thefewest calories, those in Zone 5 the most. (Everyone gets a cup anda half of vegetables.) The cafeteria is somewhat covert aboutportions; nobody has to know anybody else’s zone.

Rabena explains all of this to new hires during a Nutrition101 session. Like Serrano, she’s someone new hires meet earlyon, and her consultation, like his, kicks off with a series ofquestions — medical history, health goals, eating habits — beforediving into the program’s theory. Her meal plan’s mantrais what it calls the 80/20 rule: Eat “clean” 80 percent of thetime, “and then 20 percent of the time realize that we are allhuman,” she says. “Parties happen.” All food served in theoffice meets the “clean” requirement.

For lunch, I have sesame-ginger salmon over wild rice, witha pile of roasted vegetables dumped on top. It’s delicious andfilling, and I realize that for free meals like this every day, I’dhappily submit to some health assessments, too.

Michael Forman, the firm’s chief executive officer, won’tsay how much he pays for the program, except that the cost is “notinsignificant.” (Exos won’t say, either, explaining that it doesn’thave a “set price” for its wellness offerings.) ButForman says his company’s health insurance costs are down 23percent year-over-year and that its participating employeescollectively reduced their body fat by 10 percent in theprogram’s first year. One employee, Zach Cain, tells me he lostover 45 pounds in a year and a half.

Mattke, the researcher at RAND, says a program like FSInvestments’ “will never, ever” have a return on itsinvestment. RAND’s studies have found that while such programscan significantly reduce absenteeism, the savings to employersaren’t enough to make them pay off financially.

But Forman argues that his programhas significant benefits beyond insurancesavings: keeping workers at “peak performance” and helping toattract and retain talent. “If people have the outlet ofexercise and people eat healthy, they're going to feel better aboutthemselves,” he says. “They're going to contribute better athome and at work.”

Still, for employees, all that healthy living can take somegetting used to. There’s no soda or candy, although FS says it goesthrough 125 gallons of infused water a day. The cafeteria doesn’tdo dessert, besides dark chocolate squares and the occasionalsorbet. Employees joke about smuggling in“contraband” and “Exos-approved” treats for birthdays. “Thosefirst few months were pretty tough. I went through carbwithdrawal,” says Linda Dietch, who started her marketing jobat FS a year and a half ago. “It feels like I want sugar all thetime, and I can't have it. These little squares of chocolate arethe only treat that I have to look forward to.”

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