Gynoid Fat: Function and Importance in Fertility
By Dr. Kate Dudek
Women have been judged on their appearance since ancestral times. Those who carry their weight around their hips, breasts and thighs, have long been considered to be more attractive than those who are more 'apple-shaped' and carry their weight around the upper half of their body.
Changing body shapes
The distribution of body fat varies by both age and sex. In childhood, males and females have a similar body shape, but with the arrival of puberty comes an influx of sex hormones, which play a role in determining where fat will be stored over the repoductive years.
Oestrogen is the predominant female sex hormone. It inhibits fat deposition in the abdominal region and stimulates fat deposition around the hips and thighs (the gluteofemoral region). Testosterone is the main male sex hormone. It stimulates fat deposition around the abdomen and inhibits fat build up around the gluteofemoral region. Women with PCOS often have reduced oestrogen and higher circulating androgens (including testosterone); they also frequently present with male-like fat distribution.
Fat that is stored around the hips, breasts and thighs after puberty is known as gynoid fat. The fat that accumulates around the abdomen is known as android fat. Gynoid fat is also known as 'reproductive fat'. Comprised of polyunsaturated fatty acids, it provides nourishment to a female's offspring; initially contributing towards healthy development during pregnancy, then acting as a valuable energy reserve during breastfeeding. Android fat serves more of a protective role, to be utilised when energy reserves are low.
Waist to Hip Ratio (WHR)
The distribution of gynoid body fat is measured using WHR. Typically, during the reproductive years, the ratio is lower in females than in males:
- Healthy, premenopausal women: 0.67 - 0.80
- Healthy men: 0.85 - 0.95
After the menopause, a women's ratio will often increase and her body fat distribution will more closely resemble that of a normal male. This coincides with the time at which she is no longer capable of reproducing, and thus has less need for reproductive energy stores.
WHR is unique in that it is the only body feature that serves as a reliable marker of a female's age as well as her general reproductive status.
The benefits to having a low WHR....
Women with a low WHR have a reduced risk of heart disease, type 2 diabetes, and various cancers. They typically have fewer mental health issues and are less likely to experience depression. Maintaining a low WHR (ensuring a proportion of gynoid fat remains) after the menopause can also help to protect against cognitive decline.
From a reproductive perspective, a low WHR correlates with more regular menstrual cycles, and a healthy supply of oestrogen and progesterone during ovulation. Women with a low WHR also have a cervical/uterine environment that is favourable to sperm penetration. WHR can also serve as a predictor of the outcome of fertility treatment. Interestingly, a study has shown that all women who have regular ovulatory cycles will experience a reduction in their WHR when they are at the most fertile stage.
....and why it puts you at an evolutionary advantage
Women with more gynoid fat and a lower WHR are considered more attractive. This is a fact that is 'programmed' into our subconscious and probably goes back in time to our ancestors. These women will find it easier to find a mate, they will then find that their bodies are primed for reproduction and pregnancy. Women with a low WHR will generally have fewer health issues. The consequences of this for their offspring are that they pass on fewer heritable health problems, meaning that their children also have fewer health complaints.
Fashions change over time and with it, our perception of the 'ideal' body shape. However, the appeal of the hourglass body shape remains, perhaps because intrinsically it puts us at a biological advantage and indicates that we are not only capable of reproduction, but likely to produce strong, healthy offspring.
- Forte, R, et al. “The Body Fat-Cognition Relationship in Healthy Older Individuals: Does Gynoid vs Android Distribution Matter?” The Journal of Nutrition, Health & Aging, vol. 21, no. 3, 2017, pp. 284–291., doi:10.1007/s12603-016-0783-1.
- Jasieńska, G, et al. “Large Breasts and Narrow Waists Indicate High Reproductive Potential in Women.” Proceedings, Biological Sciences, vol. 271, no. 1545, 22 June 2004, pp. 1213–1217., doi:10.1098/rspb.2004.2712.
- Kirchengast, S, and M Gartner. “Changes in Fat Distribution (WHR) and Body Weight across the Menstrual Cycle.” Collegium Antropologicum, vol. 26, Dec. 2002, pp. S47–S57.
- Singh, D, and D Singh. “Role of Body Fat and Body Shape on Judgment of Female Health and Attractiveness: An Evolutionary Perspective .” Psychological Topics, vol. 15, 2006, pp. 331–350., core.ac.uk/download/pdf/25857452.pdf.