Polynesian people tend to be larger than most other populations due to a combination of genetics shaped by centuries of ocean voyaging, naturally higher muscle mass and bone density, and a modern dietary shift that has amplified these traits in unhealthy ways. No single factor explains it. The full picture involves evolutionary pressure, a specific gene variant found almost exclusively in Pacific Islanders, body composition that differs from European and Asian populations, and dramatic changes in food supply over the past few decades.
A Gene Variant Almost No One Else Has
One of the most concrete biological explanations centers on a variant in the CREBRF gene (rs373863828). This variant promotes greater fat storage while using less energy than the standard version of the gene. It’s common across Pacific Island populations: about 26% of Samoans carry it, along with 24% of Pukapukans, 20% of Cook Island Māori, 17% of New Zealand Māori, 15% of Tongans, and 13% of Native Hawaiians. In non-Pacific populations, fewer than 0.1% carry it. The variant is linked to higher BMI and also influences fasting glucose and type 2 diabetes risk.
What makes this gene variant so significant is that it didn’t just persist by accident. Research on Tongan genomes estimated that positive natural selection began driving this variant’s frequency upward roughly 100 generations ago, during the period when Polynesian ancestors were making their longest and most dangerous ocean crossings. People whose bodies stored energy more efficiently had a survival edge during weeks at sea with limited food. That advantage was passed on and concentrated over time.
Why Ocean Voyaging Shaped Body Size
The “thrifty genotype” hypothesis proposes that genetic variants favoring efficient energy storage were selected for during the colonization of the Pacific, when long voyages and scarce island resources made metabolic efficiency a matter of life and death. The most intense selective pressure likely occurred during the expansion from Near Oceania (islands closer to Southeast Asia) into Remote Oceania, the vast, isolated stretch that includes Samoa, Tonga, Hawai’i, and New Zealand. These crossings could cover thousands of kilometers of open water.
This hypothesis has been debated. Some archaeologists and anthropologists have argued that Pacific peoples didn’t actually face the kind of prolonged starvation the theory requires, pointing to evidence that voyagers carried provisions and that many islands were resource-rich upon arrival. However, more recent genetic analysis has strengthened the case, at least for specific variants like the CREBRF one. The selection signal in the genome is real, even if the exact environmental pressures are still debated. Interestingly, that same genomic analysis found evidence of recent polygenic selection in the opposite direction, favoring lower BMI in more recent generations, suggesting the evolutionary picture is still shifting.
More Muscle and Bone, Not Just More Fat
Polynesian size isn’t just about body fat. A comparative study of European, Māori, Pacific Island, and Asian Indian adults using full-body scans found that Pacific Islanders carried more appendicular muscle mass (the muscle in your arms and legs) and more bone mineral content than other groups. This means that at the same BMI number, a Polynesian person typically has a different ratio of muscle to fat than a European or Asian person.
This matters because BMI, the standard measure used worldwide to define overweight and obesity, doesn’t distinguish between muscle and fat. Research from New Zealand found that standard international BMI cutoffs for overweight and obesity should be raised by an average of 1.5 and 1.8 points respectively for Pacific Island girls to reflect the same actual body fat percentage as European children at those thresholds. In other words, a Pacific Islander classified as “overweight” by global standards may carry no more body fat than a European person at a “normal” BMI. This doesn’t erase the genuine health risks many Pacific Islanders face today, but it does mean the raw obesity statistics overstate the problem to some degree.
The Modern Diet Changed Everything
Traditional Pacific diets centered on root vegetables like taro and yam, fresh fish, coconut, and fruit. Over the past several decades, urbanization, rising incomes, and global trade brought a flood of imported processed foods into island nations. Cheap, energy-dense products high in sugar, sodium, and trans fats have displaced whole foods across the region. Processed meats like mutton flaps (fatty lamb belly cuts) and turkey tails became dietary staples, so much so that Tonga eventually introduced food taxes to reduce their consumption.
The shift hasn’t simply replaced traditional fats with new ones. The WHO has noted that vegetable oils and other imported fats have been added on top of the coconut-based fats that were already part of Pacific diets, increasing total fat intake rather than substituting for it. Combined with less physical activity from increasingly urbanized lifestyles, this nutritional transition has produced staggering obesity rates. American Samoa leads the world at over 70% adult obesity. Tonga sits at 63%, Samoa at 53%, and French Polynesia at 47%. These rates reflect a population genetically inclined toward efficient energy storage now living in an environment of caloric abundance.
Cultural Attitudes Toward Body Size
Polynesian cultures have traditionally held positive views of large bodies, associating physical size with strength, status, and prosperity. However, the reality of modern attitudes is more nuanced than the stereotype suggests. A study of Samoans in both Samoa and New Zealand found that ideal body sizes were actually slim, and body dissatisfaction and weight loss attempts were common. The key cultural difference wasn’t a preference for being large. It was the absence of the intense stigma against obesity seen in Western societies. People above normal weight didn’t tend to perceive themselves as obese and remained positive about their bodies and health.
This cultural buffer has complex health implications. It may protect against the psychological harms of weight stigma, including depression and disordered eating. But it can also mean that weight-related health risks go unrecognized longer, since carrying extra weight doesn’t trigger the same alarm it might in cultures with stronger anti-fat attitudes.
Genetics and Environment Working Together
The size of Polynesian people reflects layers of influence that reinforce each other. Genetic variants selected over centuries of Pacific voyaging promote energy-efficient metabolism and fat storage. A naturally robust skeletal and muscular frame means Polynesian bodies are built larger at baseline. And a rapid shift from traditional whole foods to imported processed foods has pushed a population already primed for energy storage into caloric surplus. None of these factors alone explains the pattern. A Polynesian person eating a traditional diet on a physically active island lifestyle would still tend to be larger and more muscular than average, but the extreme obesity rates seen today are a modern phenomenon driven by dietary and lifestyle changes colliding with ancient biology.