Before Soylent There Was SlimFast — And Before That There Was This

Photographed by Nicole Maroon.
Introducing the Fad Diet Hall Of Fame: This month, The Anti-Diet Project is exploring some of history’s legendary and infamous fad diets, and the people behind them. These are the origins of some of today’s most popular health trends and food beliefs. Some of these fads are incredibly strange — and all are uncomfortably familiar.
A note to readers: Features on The Anti-Diet Project do not typically include content warnings. However, this piece refers to a historical event involving a particular diet trend, and diet products, which led to many deaths. Therefore, this story includes specific references to calories and dieting techniques, which some readers may find triggering. Please be mindful. And, as always, if you're concerned that you or someone you know is struggling with an eating disorder, please contact NEDA online or via the helpline: 800-931-2237.
Last month, Soylent went on sale at 18 7-Eleven stores in southern California. Up until then, the high-tech meal-replacement beverage had only been available online, fostering a cultish (and distinctly male) following amongst the Silicon Valley crowd and body-hack enthusiasts. Soylent already weathered its first wave of controversy, recalling its bars and powder last year after consumers reported severe gastrointestinal symptoms. But in 2017, it regrouped, reformulated, and landed $50 million in Series B funding. Now, its tidy white bottles sit on convenience store shelves, nestled up against its predecessor: SlimFast.
Next to the smooth, matte minimalism of Soylent, that tomato-red SlimFast bottle, with labels like Cappuccino Delight and Rich Chocolate Royale must look positively goofy — a throwback, but not the good kind. SlimFast looks like Soylent’s lame aunt, who sends long, awkward text messages and signs them with her full name. But if Soylent were smart, it would listen to Aunt SlimFast, because she knows this rodeo better than anyone. She knows what it’s like to be the young and modern miracle, stepping onto the scene to oust an older product, while building off its business model. Forty years ago, SlimFast was Soylent — and Metrecal was the dying star. Here’s the twist: Metrecal users were actually dying.
Like all diet fads, Metrecal reflected the ethos of its era. In the late 1950s, America was smack in the middle of a post-war boom. Babies, the economy, the suburbs, consumer goods — everything seemed to be booming left and right. After half a century of war and depression, the country was naturally thrilled to take a goddamn break and enjoy itself. Americans (white Americans, to be clear) enjoyed the ease of suburban life (and the distance it often put between them and the struggles of non-white Americans).
Technology was booming too, with the Space Race off and running, and televisions in nearly every home. With TV came the first TV dinners, a hallmark of the era’s primary food trend: convenience. This was the age that introduced things like canned soda, instant ramen noodles, Tang, Pop Tarts, and virtually every major fast-food chain. The current adult generation had lived through wartime rationing, and the one before that had weathered the hungry Dust Bowl years, so it’s no wonder that the pendulum swung so far, making food as easy and readily available as possible. And nothing was easier or more readily available than Metrecal.
Mead Johnson & Co. created two emblematic products of the 1950s, though neither were exactly food, nor were they designed for general consumption. Enfamil was a powdered baby formula (the first to be patterned on the makeup of human breast milk and the first one to be recommended by doctors). Sustagen was a slightly modified version of Enfamil, designed as a meal replacement for people unable to eat solid food. Diet historian Susan Yager writes in her book, The Hundred Year Diet: “In 1959, in a stroke of marketing genius, executives realized that the drink was often consumed by neither infants nor invalids, but by adults trying to lose weight.” Quickly, Mead Johnson set about tweaking the formula, upping the protein content, and releasing a brand new product in less than a year. An anecdote particularly iconic of the age is the “convenient” way the product got its name. Rather than have people sit around and think of one, they entered the words “metered” and “calories” into a new IBM syllable-scrambling program, which spat out the snappy mashup, “Metrecal.”
A woman browses a rack of skirt suits in a high-end department store. An ominous male voiceover asks: Is this the day you finally do something about your weight? She selects a 12, smiling. She tries it on. She shakes her head. She exits the dressing room, handing the item to a young, lithe shop assistant, saying, “Nothing seems to fit.” The shop assistant replies, “Oh,” then pauses, just long enough for the moment to become uncomfortable. “Would you like to try on some...14s?” The shopper bites her lip in dismay. Is this the day? the voiceover asks again. All it takes is a little bit of willpower. And Metrecal.
The only thing more simple and brilliant than Metrecal’s creation was its marketing. Men were occasionally featured in advertisements, but Metrecal makers recognized that their primary target was women, and they knew how to hit them right where it hurt. TV commercials showed the tale of the devastated shopper, and print ads featured a woman — arms folded, brow furrowed — glaring at the slender silhouette of another. Once again, the tag lined asked if this was the day you finally decided to do something about it.
Later, Metrecal became one of the earliest diet products to be marketed with a medical angle — sort of. Enfamil had been clinically approved, and though Metrecal was a different product with a different purpose, Mead Johnson began indirectly alluding to doctors in its advertisements. A later commercial opens on two young, slender women in an office. The voiceover (still male, but now British, to boot) begins: Because overweight not only detracts from appearance, but impairs health and shortens life, your physician is your best council on weight control. Here, one of the women sits at her desk — but she doesn’t pick up the phone and call her doctor. She opens a drawer and pulls out a can of Metrecal.
Doctors had nothing to do with Metrecal, but weaving in these vague mentions of science and health gave the product “the illusion of being an FDA-approved prescription,” Yager says. “And of course,” she adds, “look how often we still see that with ridiculous schemes.”

Like all diet fads, Metrecal reflected the ethos of its era.

The diet plan itself was easy, in that there was really no plan at all. Instead of food, you drank four cans of Metrecal per day, providing a daily intake of 900 calories, less than half of the average daily intake, (and, they claimed, “sound nutrition”). In advertisements, the company suggested that if you were interested in slower weight loss, you might drink Metrecal for only one or two meals a day. But in the age of quick-and-easy, no one wanted to take things slow. Furthermore, a study conducted at Phoenix’s Good Samaritan hospital found that 97% of people who followed the Metrecal-only diet lost half a pound a day, on average. (Yager adds: “What about the 3% who didn’t lose weight even when starved? The question was never raised.”)
Metrecal was an instant, astronomical hit. In its first piece on the nationwide Metrecal craze, The New York Times reported that, “Small talk at cocktail parties invariably turns to whether the chocolate, butterscotch, or vanilla flavor of the mix is preferred.” Doctors generally agreed, the piece continued, that Metrecal was, “perfectly safe for the average person to use.” Time wrote that, “no diet fad has ever taken the U.S. so overwhelmingly as the craze for the food supplement Metrecal.”
Only The Chicago Tribune seemed to have some reservations about the product, pointing out some of the less flashy realities of Metrecal. For one, it had no fiber, which could cause “what the TV commercials delicately call, ‘loss of normal regularity,’” the piece said. For another, most of the weight initially lost on the Metrecal diet was probably due to a dramatic drop in salt intake, resulting in rapid water loss from bodily tissues. That dehydration could be dangerous, especially for those who used Metrecal in the hot summer season, when dieters often tried to slim down. Finally, the doctor quoted in the Tribune’s piece commented on Metrecal’s “all it takes is a little will power” hook: “It seems to me that if an individual has enough willpower to stay on one of these liquid diets, he’d have willpower enough to do most anything — including sticking to a low-calorie, balanced diet of a standard type.”
Nevertheless, Metrecal soared. President Kennedy had Metrecal kept in the White House staff lunchroom, and reportedly often drank it himself before bed (as did the royals of Greece and Saudi Arabia). Bergdorf Goodman advertised a purse flask, saying, “[It] could be the solution for every secret Metrecal drinker.” In 1961, the popular tiki bar Trader Vic’s began serving a Metrecal cocktail, mixing the drink with rum and nutmeg.
Mix-ins weren’t part of the diet, of course, but it soon became clear that many people were doctoring the chalky substance in order to stick to the plan, at least in theory. Metrecal wasn’t just a fad diet, but a fad, period. Like any popular health trend, it was about hipness and modernity; Americans wanted to be in the in-crowd — or as later ads called it, “the Metrecal for lunch bunch.”
“It just caught on,” Yager says. Liquid diets had been coming in and out of fashion for at least 100 years, “but this one caught on to such a huge extent, because there really hadn’t ever been anything quite like it before. You could buy these cans of diet food, and just have three or four of them a day, and lose weight. What could be easier than that?” On the flip side, though: “What could be duller than that.”
Liquid fads typically seem to flare out faster than other diet trends (see: the most recent juice-cleanse craze, which evidently peaked in 2015, while things like Atkins and the ensuing low-carb wave have endured, in some form, since the 1990s). By the mid-1960s, consumers were demonstrably sick of drinking butterscotch baby formula, and Metrecal scrambled to win them back. New commercials suggested freezing Metrecal and eating it like ice cream. The company frantically churned out a new line of flavors. 42 fattening days until New Year’s Eve! A 1964 ad used this threatening hook, printed over a photo of various cocktail glasses filled with Metrecal on ice. 6 delicious ways to fight back with Metrecal!
But they were too late. By then, the market had been inundated with approximately 700 copycat products, like Sego, Bal-Cal, and Carnation Instant Slender (which later became Carnation Instant Breakfast). The new products used some variation of the Metrecal formula, but with new flavors, new packaging, and new (though quite familiar) ways of nabbing customers. Nibbling defeats dieting, but Sego at mealtime helps you through the Temptation Hours.
Sego also boasted of having “10% more protein” than Metrecal, since consumers seemed to focus on this key ingredient. Next, Sego made the most obvious innovation: food. The brand offered pudding, soup, and eventually, diet bars. Liquid was still the central component of the plan, but now dieters were allowed the occasional chewable meal. Metrecal users began to flock to Sego, and its own copycats, in droves. Sego upped the advertising ante too, with its “would he think so now” campaign:
How slender you were in the glow of the fire… one print ad reads, over an image of a young, blond woman standing beside a fireplace, smiling at a man seated just out of frame. Would he think so now? Another ad showed a couple on the beach. Your slender figure was part of your charm. Would he think so today?
Metrecal retaliated with its own line of snack foods, including wafer cookies and chunky soups. It launched a new diet drink called Shape, this one targeted toward teenaged girls. And, not to be outdone, in 1970 it released a print ad for it, which can truly only be described as un-fucking-believable: Three young-looking teenaged girls stand on a beach. Two are in bikinis and one is wearing a shirt over her swimsuit. The text printed above their heads, in bold lettering, reads: You know why she’s wearing that sweatshirt, don’t you. The ad copy continues: Beneath that floppy sweatshirt, she’s a little overweight. You knew that. Because right now, you’re a little overweight, too. That’s bad. This year’s bathing suit hides nothing...Face it, you’ve got to stop eating. After another couple hundred words about how disgusting you are, the ad concludes with the simplest tag line yet: Shape. Stop eating.
Ads like these now seem like the desperate tactics of a dying industry (“Metrecal: A Shadow Of What It Was,” The New York Times lamented). The liquid-diet fad was clearly on the wane. But Metrecal, Sego, and their competitors hung on for a few more years, and in the end, it wasn’t the bland products or the outrageous marketing ploys that killed them. It was the fact that people were dying.

In the end, it wasn’t the bland products or the outrageous marketing ploys that killed them. It was the fact that people were dying.

“Liquid Protein Diet May Kill,” read the front page of The Chicago Tribune on November 13, 1977. That year, the FDA and the CDC began investigating reported deaths of people on liquid protein diets. In November, it released the first warning, claiming that at least 16 women had died as a result of using liquid diet products. “We have every reason to believe that the liquid protein diet was at least a contributing factor or a cause of the deaths,” said FDA Commissioner Dr. Donald Kennedy. “The low‐calorie protein diets, especially the liquid protein diets, have great potential for damage.” The following year, it was found that 58 deaths were linked to liquid diets (between late 1977 and early 1978 alone). All of them were women between the ages of 25 and 44. The CDC jumped in with findings from its own study, stating that, “in this age group, prolonged use of the liquid protein diet accounts for a significant increase in mortality.”
Perhaps the most frightening thing about these deaths is that there is still no exact consensus as to precisely what caused them. A handful of studies have tried to pinpoint it, but as of now it’s assumed that many of these products contained poor quality protein, and were extremely deficient in essential nutrients, like potassium (which is necessary for cardiac function). It’s almost certain that some people died due to a combination of underlying health issues and the diet, but it’s also accepted knowledge (affirmed by the FDA) that these types of diets are simply not safe when they’re not supervised by a medical professional.
Metrecal was temporarily yanked off the shelves, along with all of its competitors. Sales in liquid diet products dropped 95% between 1977 and 1978. As of 1982, the FDA required that all “very low calorie” liquid protein diets (those with fewer than 400 daily calories) come with a label, warning that the product “may cause serious illness or death.” Offering approximately 900 daily calories, Metrecal and Sego would technically have been able to avoid the warning label, but they were — and remain — recognized as unsafe. To this day, regulators refer to this scare as a turning point — the first weight-loss fad to be treated as an “outbreak.” In his address marking the 60th anniversary of the CDC, Director Wiliam H. Foege, MD, wrote: “During the late 1970s, the world appeared faced with a new, emerging infectious disease (e.g., Lassa fever, toxic shock syndrome, and Legionnaires disease)...However, increasingly, outbreak investigations involved noninfectious health problems, such as those involving baby foods and diet preparations. The deaths of women attempting to lose weight while consuming liquid protein diet products led to an understanding of the risk for physiological consequences on cardiac function posed by such products.”
The original liquid-diet brands never rebounded after the scare. In the late 1950s, they’d been the wave of the future, the promise of instant beauty and effortless help. But time marches on, and by the mid-1960s, they were a dull and flavorless grind. By the ‘70s, they’d become both boring and lethal. And now there was a new liquid diet on the scene.
SlimFast was initially released in 1977 — just in time to be recalled. But with all the competition gone, Thompson Medical Company (which created SlimFast) saw an opportunity. Whereas Metrecal’s makers had approached their product launch with aim of just getting it out there ASAP, Thompson Medical spent years carefully watching the market, testing it out (in Southern California convenience stores), and refining the brand to meet its customer’s needs. The woman of the ‘80s was seen as busy, competitive, and professionally focused. She had no time or interest in cooking or counting calories, and SlimFast could do it for her. The marketing angle was skewed ever so slightly toward nutrition and away from calories, with the package recommending a shake for breakfast, a shake for lunch, and a “sensible dinner.” SlimFast was still a liquid diet, but one that had learned from its predecessor’s successes — and, more importantly, from its mistakes — then gave it a sharp new look and slightly better flavor. It was another slam dunk.
From there, the story is much the same. SlimFast enjoyed years of success, interest peaked, then fizzled out. The company made occasional stabs at rebranding (including the addition of bars and snacks), but as the Times once said of Metrecal, it is “a shadow of what it once was.” These days, SlimFast sits beside Soylent on 7-Eleven shelves, a relic from another age. Soylent has the ear of young consumers and the edge of contemporary technology. But even if it succeeds in going mainstream, as the company intends, it can’t escape the ravages of time. Soylent will one day be old and boring — just like the rest of us will.
The Anti-Diet Project is an ongoing series about intuitive eating, sustainable fitness, and body positivity. You can follow Kelsey's journey on Twitter and Instagram at @mskelseymiller, or right here on Facebook. Curious about how it all got started? Check out the whole column, right here.
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