Take one look at the latest consumer surveys and it becomes apparent: We have become a nation of food tribes.

A whopping 44 percent of adults now say food restrictions, food allergies, or avoidance of certain ingredients dictate what they eat, according to a 2014 Packaged Facts report. Of those, one in three is trying to get off sugar, one in four is on a “high protein” diet, and 6.5 percent are “lactose free.” Many are motivated not just by a wish to lose weight but, rather, a “new lifestyle” inextricably linked with their social circles and stances on environmental and animal welfare issues. Nearly 1 in 3 adults is trying to go gluten free; one in 10 millennials is vegetarian or vegan; and as many as 3 million people identify with the “ancestral health movement,” a.k.a. Paleo, recent surveys show.

The notion of people aligning themselves around diet is nothing new. “Humans have a seemingly innate desire to belong, and food preferences have always been a way to do that,” notes Marion Nestle, a food politics blogger and professor of nutrition at NYU. What’s different today, she and other observers say, is the sheer number of people belonging to a so-called food tribe—and the profound influence they’re having on industry. “They are having a broad impact on the way people eat, and manufacturers, retailers and food service operators are being forced to respond,” says Amanda Topper, a food analyst for market research firm Mintel.

What’s the rationale behind America’s top food tribes? How can companies best meet their needs? And, most importantly, which are fads and which are here to stay?

Here’s a primer.

GLUTEN-FREE

The gist: According to the Archives of Internal Medicine, 1 in 133 people suffers from celiac disease—an autoimmune disorder in which gluten prompts antibodies to attack the intestinal wall, impairing nutrient absorption. Once diagnosed, they are advised to be 100-percent gluten-free. At least another 7 percent suffer from “gluten sensitivity,” according to the Center for Celiac Research at Massachusetts General Hospital. While there’s little evidence that going gluten-free prompts weight loss, 25 percent of consumers do it for that reason, reports Mintel. Some studies show that eschewing gluten can quell irritable bowel syndrome, fibromyalgia, rheumatoid arthritis and psoriasis—a prospect that has many grabbing for GF-food for its “general health halo” says Topper. Interestingly, only 18 percent of gluten-free dieters have celiac disease.

The numbers: U.S. sales of gluten-free foods soared 63 percent from 2012 to 2014, reaching $8.8 billion, according to Mintel. Sales of snacks grew the most, up 163 percent, while breads and cereals spiked 43 percent. Mintel forecasts the market to grow to $14.2 billion by 2017. But there are signs consumers may be growing tired of the GF craze, and food companies may be backing off. Forty-four percent of consumers see it as a “fad” (up from 32 percent a year earlier) ,and only 27 percent say GF foods are worth the price. On the shelves, 34 percent of all products now make a gluten-free claim, down slightly from 37 percent in 2013.

The takeaway: Food and beverage industry analyst Darren Seifer, of the NPD Group, says the gluten-free party is winding down. “It peaked at the end of 2013 and now it is starting to pull back,” he says, adding that this relatively short cycle is par for the course for restrictive diets. “Historically speaking, they make their flash in the pan and they fade away. When people are trying to get more of something into their lives (more protein, more whole grains, etc.) those trends are longer lived.”

That’s not to say there’s no room left to serve those already committed to gluten-free. “People want bread, pasta, and pizza, and they want more varieties,” Topper says. 

In January, Pizza Hut teamed up with GF bread-maker Udi’s to launch a GF pizza at 2,400 locations, and Coors launched a GF beer in Portland and Seattle. Other companies have simply slapped a gluten-free label on items like corn chips and yogurt that never did contain gluten. (Warning: Half of consumers polled by Mintel said they found that misleading). Seifer’s advice for companies considering entering the space: Carefully analyze what reformulating and re-packaging will cost, and proceed with caution. “Consider a line extension and try it out in a few markets,” he says. “I certainly wouldn’t build a whole plant around it.”

PALEO

The gist: Said to mimic the diet of “pre-agricultural, hunter-gatherer ancestors,” paleo calls for more protein, fewer carbs, and more fat. It favors nuts, seeds, oils, and grass-fed meat, while forbidding dairy, grains, legumes, refined sugars, and salt. “Seventy percent of the calories in the typical U.S. diet come from refined sugars, grains, vegetable oils, and dairy. Paleo reduces our reliance on those,” says Loren Cordain, whose 2002 book The Paleo Diet helped launch the movement. He argues that no other mammal consumes dairy past the weaning period and that grains are hard to digest.

At least 16 human studies have looked at the diet’s impact on conditions like multiple sclerosis and diabetes, with many showing favorable results. But critical dietitians say fat can be hard on the heart (a claim several new studies dispute) and lack of carbs and their inherent fiber can leave dieters fatigued and constipated.  “My number one concern about Paleo is compliance long-term,” says Jessica Crandall, RD, of the Academy of Nutrition and Dietetics.

The numbers: Between 1 and 3 million people adhere to a paleo diet, according to research by Hamilton Stapell, a history professor with the State University of New York, New Paltz. Contrary to popular stereotypes, the typical follower is not a hulky male CrossFitter but, rather, a middle-aged, affluent white woman trying to boost athletic performance, lose weight, or combat a health problem.

Stapell’s surveys show 56 percent of paleo followers are women, 92 percent are white, and 74 percent hold a college degree. Sales figures for paleo products per se are hard to come by, but the core tenants are clearly on the rise, with SPINS reporting rising sales of wild-harvested food and grass-fed beef. Products labeled “allergy-free” (devoid of lactose, gluten, and other allergens) are up 26.5 percent, and surveys show about 25 percent of consumers are trying to eat more protein.

Challenges and opportunities: Stapell says he has seen interest in the Paleo diet wane in the past 18 months, and he is doubtful it will ever go mainstream. “It will remain a fringe movement with a small but highly dedicated group of followers.”

In a possible sign of declining interest, the Ancestral Health Society abruptly cancelled its annual symposium, set to take place in Boulder in August. But others predict that while paleo may have limited staying power, its tenets of whole food and clean meat have already gone mainstream. “The word ‘paleo’ may be a little more faddish than the actual movement and what it stands for,” says Katie Forrest a vegan-turned-paleo triathlete who co-founded Epic bar in March, 2013. The company’s meat-based bars (including buffalo and liver) are now available in thousands of stores, and retailers like Earth Fare now have entire paleo sets. Even Time Magazine appeared to be endorsing the paleo credo indirectly with its June cover story declaring that “The War on Fat is Over.”

Still, Forrest says, paleo entrepreneurs face an uphill battle when it comes to overcoming stereotypes. “The government and health organizations continue to put out false information about the health and environmental impacts of meat,” she says. “We have to put a ton of effort into education.”  The greatest opportunity for companies entering the space? People are clamoring for conveniently packaged meat and whole foods, and the category is wide open.

VEGAN

The gist: Unlike other food tribes that hinge on health benefits, vegetarianism/veganism often starts with an ethical decision. “The serious vegans are generally doing it for animal rights and environmental reasons. Better health is just a nice perk,” says Jeff Kaufman, founder of Clarksville, Maryland-based Roots Market and Great Sage Vegan Restaurant. As food fads go, it has one of the larger bodies of research behind it, particularly when it comes to heart health. One 2014 meta-analysis of 21,604 people showed vegetarians have significantly lower blood pressure. Another looked at 34,192 Seventh-day Adventists (who are vegetarian) and found their lifetime risk of heart disease was 37.4 percent lower than that of meat-eaters. Dr. Kim Williams, president-elect of the American College of Cardiology, recently revealed that he’s been a vegan for 11 years and advises his patients with heart disease to do the same. The downside: Nutritionists say it can be challenging for vegetarians to get enough protein, iron, B12 and DHA/EPA found in fatty fish).

The numbers: Just 4 percent of U.S. consumers are strictly vegetarian, according to the Vegetarian Resource Group, and about half of those are vegan. While those numbers are slipping slightly, one third of Americans now say they are trying to eat vegetarian meals at least occasionally. “With movements like Meatless Monday growing in popularity, people are working more veggie-based meals into their rotation,” says SPINS research associate Samantha Rico. Retail sales of vegan products rose 6.3 percent in the past year, according to SPINS.

The takeaway: “It is never going away, but it is just too small,” says Seifer. “If you are a major food manufacturer I do not think it is a good market to go after.”

Mintel’s Topper says that if a company does opt to make vegan/vegetarian consumers its niche, it should target the products and marketing efforts toward millennials. Unlike baby boomers, who have all but given up on eschewing meat, 9 percent of the 30-something crowd is vegetarian.

SUGAR-FREE

The gist: Thirty-five years after the USDA. declared  its “war on fat,” prompting food companies to pull fat from their products and replace it with sugar or artificial sweeteners, the pendulum is swinging back.

This time, sugar is the demon.

Katie Couric’s 2014 documentary “Fed Up” challenges people to go sugar free for 10 days. Government agencies blame sugar-loaded sodas for the obesity epidemic. And a host of new studies show people who eat more sugar have not only greater rates of diabetes but also more heart disease, cancer, and wrinkles.

Artificial sweeteners have also been targeted, with one study published in December in the journal Nature suggesting sugar substitutes like saccharine alter the gut microbiome, boosting risk of a host of diseases. As a result, consumers are not only cutting back on sugar but also taking a closer look at what they’re replacing it with. “It is the biggest diet trend going right now,” says celebrity nutritionist J.J. Virgin, author of the Sugar Impact Diet.

The numbers: Sixty-five percent of consumers look for products that contain “no added sugar,” according to market research firm Eurominitor, making it the third-most-sought-after attribute (behind low-fat and the presence of certain vitamins). Packaged Facts reports that 33.4 percent of dieters are on sugar-free diets, and sales of table sugar are plummeting about 1 percent annually.

Meanwhile, sales of more natural alternatives like agave nectar, coconut sugar and honey are blowing up in the double-digits. Natural non-caloric sugars like stevia and monk fruit—said to sweeten food without raising blood sugar like fruit sugars (fructose) does—are boosting their market share too, with 29 percent of the zero-calorie sweetener market now coming from stevia and a respectable 4 percent coming from monk fruit.

The takeaway: With consumers scrutinizing not only how much sugar but what kind of sweetener they are taking in, food marketers would be wise to start developing more drinks, snacks, and deserts made with natural, zero -calorie sweeteners like monk fruit, stevia, and xylitol, says Virgin.

THE BIOHACKERS

The gist: No look at the food-tribe landscape would be complete without a glance at the burgeoning “personalized-nutrition” or “biohacking” movement, in which consumers use cutting-edge health technologies to gauge precisely what’s going on inside their bodies and adjust their eating habits accordingly.

Web-based Wellness FX allows customers to have their blood tested for things like anemia, thyroid dysfunction, or nutrient deficiencies, then use a computer algorithm and physician consultation to choose foods and supplements for them. Pathway Genomics uses DNA testing to help guide consumers, via their practitioners, to the ideal way of eating. UBiome, enables people to send in a stool sample and find out precisely what bacteria types reside in their gut, what they are missing, and how to gain a better balance via food. 

The Numbers: As a new, slightly amorphous subculture, the biohacking tribe is hard to quantify. But some metrics suggest the idea is gaining steam. The term didn’t even register on Google Trends in July, 2011, but searches have grown steadily since, spiking 30 percent in 2014. Attendance at the second annual Bulletproof Biohacking Conference in September increased 500 percent over the prior year.

According to Mintel, 18 percent of consumers now wear a digital diet and fitness tracker and another 31 percent want to try one. And come April, many probably will. That’s when Apple will roll out its health-tracking Apple Watch. Analysts predict it could sell 30 million in the first year it’s on the market

The takeaway: Stay tuned. Ultimately, says Virgin, it may be the information we glean from such “biohacking” that leads us to the tribe that’s best suited for us – be it Paleo, gluten-free, vegan or something else. Because in the end, she says: “It doesn’t matter what all the studies say if it doesn’t work for you.”

*Nutrition Business Journal dives into market data around veganism as well as paleo, gluten free and other food movements in the 2015 NBJ Food Tribes report available for purchase here.