It’s one of the more consistent findings in attraction research, and one of the more misunderstood. The preference is real, it’s measurable, and it shows up across wildly different cultures. What it actually means is where things get complicated.
The waist-to-hip ratio research
The foundational work came from psychologist Devendra Singh in the early 1990s. He found that men across multiple cultures rated female figures with a waist-to-hip ratio around 0.7 as most attractive — a waist roughly 70% the circumference of the hips — largely independent of overall body weight.
That last part matters. Preferred body size varied enormously between cultures and eras. The ratio held steadier. Singh’s work has been replicated many times, and while the 0.7 figure is less universal than early papers claimed, the general pattern survives: the contrast between waist and hips carries more weight than either measurement alone.
It might not be the butt at all
A 2015 study by David Lewis and colleagues at Bilkent University complicated the picture usefully. They isolated spinal curvature from actual gluteal mass and found men showed a strong preference for a specific lumbar curve — roughly 45 degrees of vertebral wedging — even when buttock size was held constant.
The proposed explanation is biomechanical. During pregnancy, a woman’s centre of mass shifts forward substantially. That degree of lumbar curvature is close to optimal for managing the load without spinal injury. The argument is that the preference tracks a structural feature associated with successfully carrying pregnancies, and that gluteal mass often signals it without being the thing itself.
Whether that holds up is still debated. But it suggests what people describe as a preference for one body part may be a preference for a silhouette that particular part helps create.
The fat itself is different
Here’s the part most people don’t know. Gluteofemoral fat — the fat stored on hips, buttocks, and thighs — is metabolically distinct from abdominal fat. It’s harder to mobilise, and it’s disproportionately rich in omega-3 fatty acids, particularly DHA.
DHA is critical to fetal brain development. Research by Will Lassek and Steven Gaulin found that this fat is preferentially drawn on during late pregnancy and lactation, and they reported correlations between maternal lower-body fat and offspring cognitive test scores.
Lower-body fat is also associated with better metabolic markers than abdominal fat — lower cardiovascular risk, better insulin sensitivity. So the preference may track something genuinely functional rather than arbitrary.
Where the evolutionary explanation gets shaky
Worth being honest about the limits. Evolutionary psychology has a well-documented problem with just-so stories: find a preference, construct a plausible adaptive reason, call it explained. The reasoning is often unfalsifiable, and several classic findings in the field have failed to replicate.
Cross-cultural evidence is messier than popular summaries suggest. Studies in populations with limited Western media exposure have found preferences diverging considerably from the 0.7 figure. Some research indicates the “universal” preference correlates with media exposure rather than preceding it.
And preferences shift with circumstances. Under conditions of scarcity or stress, preferred body size tends to increase — which points to something more flexible than a hardwired setting.
Culture does real work here
Aesthetic standards for this body type have swung dramatically. Nineteenth-century Europe had the bustle, engineering the silhouette with fabric. The 1920s flattened everything. The 1990s idealised a much leaner shape. The 2010s swung hard the other way, driven by celebrity culture and social media.
There’s also a history worth naming rather than skipping. Sarah Baartman, a Khoikhoi woman displayed across Europe in the early 1800s, was exhibited specifically because of her body — an episode of racialised exploitation whose legacy shapes how this topic still gets discussed. Body types associated with Black and Latina women were pathologised for most of two centuries before being commercialised in the last two decades. That history sits underneath current aesthetics whether or not it’s acknowledged.
Why the honest answer is boring
Most likely: a genuine biological bias, weak and probabilistic, amplified enormously by cultural reinforcement, and varying substantially between individuals.
Plenty of people don’t have this preference at all. Plenty have the opposite. Attraction to a specific body type explains a small fraction of who anyone actually finds compelling, and preference research measures snap judgements about images rather than what draws people to each other over time. A gay AI companion built around a particular body type will still hold attention through personality rather than proportions — which tells you something about where the weight actually sits.
What to take from it
If you have the preference, it’s neither a moral failing nor evidence of anything deep about you. If you don’t, that’s equally unremarkable. And if you have the body type and have absorbed some anxiety about it, the research is broadly reassuring — this is the fat distribution associated with better health outcomes, not worse.
What the science doesn’t support is treating a statistical tendency as a standard anyone is obliged to meet. Preferences vary far more between individuals than the headline findings suggest.
For those exploring the preference in companion platforms, this guide to big ass AI girls sites covers which sites handle body-type customization properly. You can also find out more here.