Why Women Easily Gain Weight

Women naturally carry more body fat than men, and they typically also have a harder time maintaining a lean frame. The very slim figure that’s displayed in some women’s magazines is difficult or impossible for most women to obtain. In some cultures, such a figure is considered to be the ideal female form. What’s important to note though is that it’s not the natural female form, nor is it the form that the opposite sex (i.e., men) evolved, biologically speaking, to favor.

The evolutionary origins of female fatness

The explanation for why the part of the female body that consists of adipose tissue is fairly voluminous, as well as why women have a propensity to store fat, can be found in our evolutionary past…

Energy is needed to produce offspring

The primary reason why women have a tendency to store fat is that they are capable of producing offspring and giving birth. A woman not only needs energy to fuel her own body; she also needs to be able to manufacture additional bodies.

When compared with the modern woman, women of the past generally got more children and spent a much larger portion of their lives either pregnant or breastfeeding. In this day and age it’s not uncommon for women to only get one or two children and breastfeed for a couple of months (if that) following each childbirth. In an evolutionary context, however, this type of reproductive pattern is an anomaly.

In combination with the fact that in the type of natural environment that we humans evolved, food, and in particular energy-dense foods, wasn’t as easily and abundantly available as it is today, this helps explain the buxomness of the female body. Given that energy-rich foods was once hard to come by, it’s not surprising that genes that enable efficient storage and conservation of energy have been favored and maintained by natural selection.

The selection pressure acting on such genetic variants have likely been particularly strong on the female side of humanity, seeing as that’s the side that babies come from. A woman of the Paleolithic who carried quite a bit of body fat and was ‘good’ at storing energy during times of plenty would have had an obvious fitness advantage, seeing as she would have had fat reserves at her disposal that could be used to fuel procreation. Such energy reserves would have been particularly valuable during times of scarcity. Basically, fat stores act as a Darwinian safety depot, by enabling survival and reproduction under variable conditions of life.

There hasn’t been a strong impetus for natural selection to constrain female body fat levels

Another facet of this issue that deserves to be mentioned has to do with the types of activities that women have historically engaged in. In hunter-gatherer societies, there’s a division of labor. Whereas the men routinely go out on long and sometimes arduous hunts, the women typically stay in or near the camp, where they care for the young and forage for berries, nuts, tubers, and the like. This is noteworthy when talking about the disparity that exists between male and female body fat levels, seeing as it helps explain why men naturally carry less body fat than women, as well as why women may find it somewhat more difficult to avoid fat gain when they are confronted with an almost unlimited supply of energy-dense foods, as is the case in modern, industrialized environments.

A fat person is at an obvious disadvantage over a lean person in activities that involve running, long walks, climbing, and/or carrying of heavy objects. Basically, fatness impairs physical performance. There’s a reason why all great endurance runners, climbers, swimmers, and so on are fairly lean.

A hunter is no different from an athlete in this respect. He’s not going to perform as well if he’s fat as if he’s lean. This is particularly true if he engages in persistence hunting, a hunting form that’s routinely used by some hunter-gatherers and that involves lengthy & fairly intense running in the pursuit of prey.

The types of activities that women have historically engaged in, on the other hand, don’t require the same level of physical stamina. A plump person will most likely find it difficult to run long distances, but will have little trouble performing daily ‘chores’ involving for example the collection of plant foods or the care of children.

This doesn’t mean that men – who were traditionally hunters – can’t get fat (they obviously can), or that women are doomed to carry around massive amounts of adipose tissue; however, it does help explain some of the observed adipose-related differences between men and women, as well as between fertile and postmenopausal women, and implies that there’s been less of a constraint on natural selection to restrict the body fat levels of women as those of men. It also helps explain why there’s a division of labor in hunter-gatherer societies on the basis of gender, with men performing most of the tasks that are very physically demanding.

Voluptuousness signals fecundity

Given that it’s historically been beneficial, Darwinian fitness wise, for women to be moderately “fat”, as opposed to skinny, it’s not surprising that the female figure is somewhat plump. Nor is it surprising that men generally like buxom women, seeing as having such an inclination is advantageous when it comes to passing one one’s genes (Actually, big breasts and buttocks may partly have evolved via sexual selection). This is part of the beauty of natural selection; it brings about a special kind of harmony and coherence.

Many statuettes portraying big women with exaggerated curves – so-called Venus figurines – have been found in various places around the world, most of which are thought to have been produced during the late Paleolithic. This doesn’t mean that we’re biologically conditioned to find the form of very big women aesthetically pleasing (the vast majority of people would probably say that the female figure portrayed by Venus figurines is overly big and fat for their liking); however, it does suggest that the curvaceous female form has long been an ‘object’ of fascination.

Perhaps needless to say, culture does affect what we consider to be attractive. It conditions us. However, culture doesn’t override biology. Our fundamental desires originate deep within us, not from the outside. The skinny figure of runway models may be what’s favored by some fashion moguls and what’s portrayed in some women’s magazines as being the ideal, but it’s certainly not what males are biologically configured to desire.

The obesity epidemic: The natural result of combining ancient, thrifty genes with a modern, energy-rich environment

We require energy, in the form of calories, to survive and reproduce. Throughout most of our evolution, it was a challenge to get a hold of this energy: unlike us, our ancient ancestors didn’t have the option of driving down to a supermarket whenever they were hungry; they had to put in quite a bit of physical work to get a hold of something to eat. Given this, it’s not surprising that we have a tendency to act in a way that maximizes the number of calories we get, while minimizing the work we have to do; that we (perhaps especially women) have evolved a liking for sweet, energy-dense foods; or that our bodies are good at conserving energy. These traits were beneficial, fitness wise, in the past, but work against us in the modern, fast food-heavy environment.

What’s important to note is that there’s a big difference between being slightly plump and being obese. Some of our distant female ancestors may have been obese (as suggested by Venus figurines); however, these women were undoubtedly in a minority. This really goes without saying, seeing as obesity, unlike “natural plumpness”, has been shown to undermine survival and reproduction. Obese people are at a higher risk of developing a whole host of diseases, when compared with lean individuals, and they also often have trouble reproducing. It’s perfectly healthy for a woman to carry quite a bit of fat in the hip and breast region, but it’s certainly not healthy to have a big belly or be obese.

The problem we have today is that we’re surrounded by foods, such as chocolate, ice cream, and doughnuts, that have a nutrient configuration that doesn’t look anything like that of any of the foods we evolved eating. It’s those foods that produce obesity – and it’s also those foods that one needs to avoid in order to avoid getting fat.