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Waist and Hip ratioWaist-to-hip ratio and hormonal balance -
Energy balance was determined based on changes in the percentage of body fat between the first and the second measurement. Packages containing plastic vials and laboratory-tested chewing gum were distributed to women before the beginning of their menstrual cycle.
During one complete menstrual cycle, every day in the morning after waking-up, women collected saliva samples in plastic tubes pretreated with sodium azide following published protocols Lipson and Ellison, Before statistical analysis, cycles were aligned on the basis of identification of the mid-cycle drop day Day 0 , which provides a reasonable estimate of the day of ovulation Lipson and Ellison, Out of women, complete data about β-estradiol indices were available for , and data about these women were used in hormonal analysis.
Women were divided into four groups based on the quartiles of the distribution of body fat percentage. The established designation of body fat quartiles was maintained in all analyses to allow comparisons between groups all women, positive energy balance women, negative energy balance women ; thus sample sizes varied in different analyses.
Differences among very low, low, average and high body fat groups in basic characteristics i. Separate comparisons of basic characteristics were also made for body fat quartiles of women with negative and positive energy balance. The same procedure was applied to test the significance of the differences in E2 indices among body fat quartiles.
Additionally, simple regression models were used to test the effect of body fat on E2 levels, with each E2 index as a dependent variable and body fat as the independent predictor. Separate analyses were conducted for women with positive and negative energy balance.
Repeated measures ANOVA was used to test the differences in E2 profiles among the body fat groups in positive energy balance women. Contrast analyses were used to test the statistical significance of differences among the four body fat groups. General descriptive statistics for all women categorized with respect to their body fat are presented in Table I.
Women characterized by very low, low, average and high body fat did not differ significantly with respect to age, birthweight and birth height, age of first menstruation, number of cigarettes smoked per day and physical activity. Women with average body fat had significantly shorter self-reported length of menstrual cycle compared with women with very low body fat Mean and standard deviation in parentheses for four body fat groups compared by one-way ANOVA tests.
Mean levels of β-estradiol in the four body fat groups are presented in Table II. Compared with women characterized by average body fat, women with very low and high body fat percentage had significantly lower levels of estradiol during the follicular phase Similar differences were also observed in comparisons between women with low body fat and women with very low and high body fat.
To test the effect of energy balance on the relationship between body fat and estradiol, separate analyses were conducted for women characterized by positive or negative energy balance. Women with negative energy balance had significantly longer usual cycle length However, they did not differ significantly in any of the anthropometric or life style parameters.
In contrast, significant differences in anthropometrics were observed within both negative and positive energy balance groups among groups of women characterized by very low, low, average and high body fat content. Additionally, in the positive energy balance group, women with very low and high body fat had significantly higher birthweight compared with women with low and average body fat 3.
Average values of E2 indices for the body fat quartiles of women with positive and negative energy balance are presented in Table III. ANOVA analyses of estradiol levels in these groups revealed significant differences in all estradiol indices between women differing with respect to body fat percentage in the positive energy balance group, but not in the negative, energy balance group.
Estradiol indices in body fat quartiles of women with positive and negative energy balance. Women with very low and high body fat had significantly lower levels of E2 over the whole menstrual cycle compared with women with average and low fat Fig.
E2 profiles in very low, low, average and high body fat groups of women with positive energy balance. The relationship between body fat and E2 levels was further confirmed by regression analyses in non-overweight women with positive energy balance, but not in those with negative energy balance Table IV.
In the range of 9. We found that nutritional status indicated by body fat percentage is an important factor associated with the levels of estradiol during the menstrual cycle. In particular, we found a non-linear U-shaped association between body fat percentage and levels of estradiol during the menstrual cycle.
We also demonstrated that energy balance confounded the association between estradiol levels and body fat in such a way that in women with positive energy balance, this association was even stronger than it was in the whole sample of women, whereas in women with negative energy balance, no relationship between body fat and estradiol levels was found.
Our findings correspond with the results of other studies concerned with levels of E2 in overweight and obese women. A decreased E2 surge was noted in studies by Grenman et al. Several authors have demonstrated that, in women, increased adiposity and obesity are related to high androgenic activity Evans et al.
This may explain the inversion in the pattern of association between body fat percentage and estradiol levels observed in our study. In accordance with our results, van der Steeg et al. Gesink Law et al. Levels of estradiol during the menstrual cycle, and especially during its follicular phase, are related to follicular diameter, oocyte quality and endometrial morphology and thickness Ohno and Fujimoto, ; Cahill et al.
Lower levels of E2 during the menstrual cycle and during ovulation frequently correlate with lower pregnancy rates, both in healthy, naturally conceiving women Lipson and Ellison, ; Lu et al.
Our results suggest that lower fecundity, conception and pregnancy rates in underweight, overweight and obese women can be mediated by an unfavorable estradiol environment. Furthermore, the negative linear association between pregnancy rate and BMI in low BMI women found in van der Steeg et al.
study can be easily explained by the linear association between body fat and estradiol levels found in non-overweight participants of our study. Results of our study clarify and extend previous evidence on the association between nutritional status and levels of reproductive steroids.
Several studies conducted on different groups of premenopausal women diabetic, obese, dieting, very lean and normal weight demonstrated contradictory results Howard et al.
This inconsistency partly results from methodological limitations, especially calculations of mean E2 levels based on no more than a few samples from each menstrual cycle. Owing to substantial intra-cycle variation in E2 levels, such sampling is vastly insufficient and can lead to errors in estimating mean E2 levels for individual women Jasienska and Jasienski, In most of these studies, estradiol levels were analyzed from a single blood sample, whereas Williams et al.
In our study, the number of samples taken from a single subject considerably exceeded this requirement. Another limitation of other studies is the use of BMI as the indicator of nutritional status.
BMI does not represent sufficient information about nutritional status and accumulated body fat Piers et al. Frequently, individuals classified as overweight on the basis of BMI are of normal adiposity, especially if they have high muscle mass Hortobagyi et al.
Conversely, women classified as normal using BMI criteria frequently have increased adiposity Frankenfield et al. In our study, this limitation was circumvented by direct measurement of body fat percentage.
The concurrent lack of a relationship between estradiol and BMI and positive relationship between estradiol and percent body fat observed in our study provides further evidence that BMI may be a poor indicator of nutritional status. In addition to making careful measurements of estradiol levels and nutritional status, we were able to estimate the energy balance of women based on changes in body fat during the observational period.
Although we are aware of the fact that changes in the percentage of body fat are only the proxy measures of energy balance, this estimation allowed us to investigate the interactions between nutritional status, energy balance and the estradiol levels across the menstrual cycle, which to our knowledge have not previously been reported.
Energy balance has been shown to influence ovarian steroid profiles in several studies Ellison et al. This fact can explain the lack of a relationship between nutritional status and levels of reproductive hormones demonstrated in populations or groups of women characterized by high physical activity Lager and Ellison, ; Jasienska and Ellison, , , women losing weight due to voluntarily caloric restriction Lager and Ellison, , and women from hunter gatherer and horticulturalist groups in Africa and Nepal Ellison et al.
In contrast, an association between body fat and reproductive hormones has frequently been demonstrated in women from western populations who generally have higher energy intake and lower physical activity; none of these studies, however, controlled for energy balance Brunning et al. The first limitation of our study is the imprecise estimation of energy balance.
Although evaluation of metabolic rate or resting energy expenditure would have been a more accurate method, Abbott et al.
Thus, we believe that a change in body fat percentage provides a good proxy of energy balance in our study participants. Another limitation of our study is that the interval between the first anthropometric measurement and the beginning of the menstrual cycle and between the end of the menstrual cycle and the second anthropometric measurement varied significantly between study participants.
Although differences in these intervals could possibly confound our findings, additional analyses conducted with exclusion of participants with longer intervals between measurements did not change the results of the analyses data not shown. Although our results point to the important association between nutritional status and energy balance and estradiol levels, our study did not investigate physiological mechanisms that were behind the observed relationship.
Several different physiological mechanism have been proposed in other studies, including those postulating the regulatory role of leptin and insulin both indirectly influencing hypothalamic secretion and directly influencing ovarian production of estradiol Smith et al.
Our results support the hypothesis of a regulatory role of nutritional status on potential fertility in reproductive age women, but only in those with positive energy balance. In women of reproductive age, energetic resources are partitioned between maintenance of normal physiological processes and reproduction.
This fat depot is built-up under favorable environmental conditions when energy intake is high, energy expenditure due to physical activity is low and total energy balance is positive. The consequences of inadequate nutritional status during pregnancy are highly adverse both to the child and to the mother.
Low body mass of a woman prior to and during pregnancy is associated with a high risk of preterm labor, intrauterine growth retardation, low birthweight of the infant and maternal depletion syndrome Jelliffe and Maddocks, ; Winkvist et al.
Short-term reproductive suppression in women with low energy reserves may function as an evolutionary adaptation protecting against these risks and improving the chances of successful reproduction in the future Ellison, , ; Jasienska, Polish Committee for Scientific Research 2 P05D 28 to G.
We are grateful to women who participated in the study, and to students of the Faculty of Public Health, Jagiellonian University, who worked as research assistants, Kolastyna SA and Yves Rocher Poland. Google Scholar. Google Preview. Oxford University Press is a department of the University of Oxford.
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Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. Materials and Methods. Journal Article. Body fat, energy balance and estradiol levels: a study based on hormonal profiles from complete menstrual cycles.
Ziomkiewicz , A. Ziomkiewicz 6. Institute of Anthropology, Polish Academy of Science. Oxford Academic. Revision received:. PDF Split View Views. Cite Cite A. Select Format Select format. ris Mendeley, Papers, Zotero. enw EndNote. bibtex BibTex. txt Medlars, RefWorks Download citation.
Permissions Icon Permissions. Close Navbar Search Filter Human Reproduction This issue ESHRE Journals Reproductive Medicine Books Journals Oxford Academic Enter search term Search. Table I. General characteristics of study participants. Age years Open in new tab. Table II.
Estradiol indices in four body fat groups. Mean E2 Table III. Figure Open in new tab Download slide. The association between E2 and body fat.
Table IV. Positive energy balance. Negative energy balance. Mean E2 55 0. Results of simple regression analysis. Short-term energy balance: relationship with protein, carbohydrate, and fat balances.
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And there is evidence that male mate preferences may reflect this trade-off, according to Cashdan. In Japan, Greece and Portugal, where women tend to be less economically independent, men place a higher value on a thin waist than men in Britain or Denmark, where there tends to be more sexual equality.
And in some non-Western societies where food is scarce and women bear the responsibility for finding it, men actually prefer larger waist-to-hip ratios.
Materials provided by University of Chicago Press Journals. Note: Content may be edited for style and length. Science News. Facebook Twitter Pinterest LinkedIN Email. FULL STORY. That's where the hormones come in.
RELATED TERMS Estrogen Overweight Misogyny Breast cancer Hormone replacement therapy Urinary incontinence Fertility Hair. Story Source: Materials provided by University of Chicago Press Journals. Cite This Page : MLA APA Chicago University of Chicago Press Journals.
ScienceDaily, 5 December University of Chicago Press Journals. Why The 'Perfect' Body Isn't Always Perfect: How Hormones Interact With Waist-to-hip Ratios In Women. Retrieved February 13, from www. htm accessed February 13, Explore More.
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Accelerating Gains in Abdominal Fat During Menopause Tied to Heart Disease Risk. The study Study Links Perimenopause to Accelerated Fat Mass Gains, Lean Mass Losses.
The study finds that women undergoing perimenopause lost lean body mass and more than doubled Print Email Share. Trending Topics. Immune System. Personalized Medicine. Health Policy.
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