What you need to know * Biological indicators tell us that skinny women are less fertile than curvy ones. * To most men, a normal BMI and waist-to-hip ratio is preferable to one that is very low. * Skinny women usually lack qualities that men notice most - the breasts and bum. It's been confirmed: Skinny women are more successful in their careers. Women who are "very thin" earn nearly $22,000 more than their "average weight counterparts," according to a study in the Journal of Applied Psychology. But if this obsession with slimming down is an outcome of women's potential financial rewards, does the same apply to their relationships with men? As this article will reveal, most men don't feel the same way as employers. Find out why men are biologically programmed to get turned on by healthy, fit and voluptuous women. 1- Waist to hip ratio counts Dividing the circumference of a woman's waist by the circumference of her hips will give you her waist-hip ratio, a number that's very important when it comes to determining a woman's level of attractiveness. In Western cultures, a waist-hip ratio of 0.7 appears to be the one that men find most appealing on a woman, and research has found that it is linked to optimal levels of female reproductive hormones and a lower likelihood of a variety of diseases. Other research has suggested that in Asia, a ratio closer to 0.6 is perceived as most attractive, while in some African and Latin-American cultures, ratios near 0.8 are preferred. Surprisingly, a wide variety of measurements result in a low waist-hip ratio. For example, Marilyn Monroe had a lower waist-hip ratio than Gisele Bundchen. The point here is that a curvaceous body, like the classic hourglass figure, makes men salivate -- and very skinny women are less likely to have that body shape. 2- Fat equals fertility Given that women's bodies were designed to carry a developing child over a relatively long gestational period compared to other species, women are natural fat storers. Back when our ancestors lived in caves and food was scarce, a woman with some meat on her bones was more likely to be able to carry a child to term. It appears, however, that it matters where the majority of a woman's fat is located on her body. More specifically, the weight a woman carries around her hips may serve as an indication as to how much fat is available to be converted into energy for fetal nourishment. In fact, some researchers have postulated that the long-chain polyunsaturated fatty acids contained in hip fat are actually critical for the developing fetal brain. A certain level of healthy fat therefore sends a signal to men that a woman is a good choice as a mate. 3- A normal BMI is hot While a woman's waist-to-hip ratio has long been touted as a measure of her physical appeal to men, recent research suggests that body mass index (BMI) may be a stronger predictor of a woman's level of attractiveness. This magic number is obtained by dividing a woman's weight by her height squared. Obviously, a BMI that falls into a normal range is most desirable, and those values are strongly linked to a woman's overall health, as well as her reproductive potential. A woman with a BMI above 25 is considered overweight, while a BMI under 18 is indicative of being underweight. Within the normal range, women with BMIs close to 19 have a lower mortality rate and are more fertile than very thin women, as a low BMI is associated with poorer health, eating disorders and reduced fertility due to amenorrhea. 4- Men like breasts (and bums) In one of the least shocking discoveries of the 21st century, it turns out there's a biological reason why men love breasts. In 2004, a study published in Biological Sciences found that large breasts, particularly when combined with a small waist, were associated with higher levels of mid-cycle estradiol and progesterone in women. Essentially, having higher levels of these hormones around ovulation means that a woman with large breasts may have an easier time conceiving. A woman with some fat on her body is therefore more appealing from a mating perspective to men. Unless they're implants, it's rare for skinny women to have large breasts. And, unfortunately, when women lose weight, one of the first places they slim down is in their chest. Healthy not skinny While it's clear that men want healthy-looking women, which includes pleasingly plump bums, the reality is that a lot of women are overweight, and the World Health Organization recognizes obesity as a global epidemic. Men find women most attractive when they take care of themselves and maintain a healthy balance of muscle and fat, so if you're a woman, the take-home message is stop dieting to be rail thin and adopt sound eating habits and an active lifestyle. Then you'll be irresistible.