A claim you hear on longevity podcasts
Strong consensus for. Of 5 studies that test it, 5 agree.
The claim checked: More body fat means more estrogen, in women and in men Hear it at 11:29
All five studies agree. Pooled data from 13 studies of women past menopause found estradiol, the main estrogen, was 47% higher in obese women than in thin women, and free estradiol 89% higher. In trials, women who lost weight or body fat lowered their estrogen.
Computed from 5 studies that test this point, each judged by two readers, in full. 10 more studies are waiting for a full read and do not count yet.
“So, we know that when our percentage of body fat is higher, we we actually produce more estrogen. And that's true for men and women.”
trial or observed group · 2011
“Overall, total oestradiol was 47% higher and calculated free oestradiol was 89% higher in obese women than in thin women.”
Circulating sex hormones and breast cancer risk factors in postmenopausal women: reanalysis of 13 studies. Br J Cancer
Who: Postmenopausal women not using hormone therapy who served as non-cases in 13 prospective studies (Endogenous Hormones and Breast Cancer Collaborative Group), mostly of white European origin
PMID 21772329
trial or observed group · 2003
“Women who were in the top quartile for body fat mass had almost twice as high a serum concentration of estradiol compared with women in the lowest quartile, and the result was statistically significant (p trend, 0.048).”
Adiposity and sex hormones in postmenopausal breast cancer survivors. J Clin Oncol
Who: Postmenopausal women with incident stage 0-IIIa breast cancer in Western Washington and New Mexico (HEAL study), measured 4-12 months after diagnosis
PMID 12743149
controlled trial · 2012
“Weight loss significantly lowered serum estrogens and free testosterone, supporting weight loss for risk reduction through lowering exposure to breast cancer biomarkers.”
Reduced-calorie dietary weight loss, exercise, and sex hormones in postmenopausal women: randomized controlled trial. J Clin Oncol
Who: Overweight or obese (BMI >=25), sedentary postmenopausal women aged 50-75 in Seattle (NEW trial), mean BMI 30.9, 47.2% body fat
PMID 22614972
controlled trial · 2015
“Body fat largely mediated the effects of exercise on these hormones, suggesting that fat loss in particular is most important in influencing sex hormone levels which are associated with postmenopausal breast cancer risk.”
Effect of weight loss, with or without exercise, on body composition and sex hormones in postmenopausal women: the SHAPE-2 trial. Breast Cancer Res
Who: Overweight or obese (BMI 25-35), insufficiently active postmenopausal women aged 50-69 in the Netherlands (SHAPE-2), mean body fat 44%
PMID 26330303
pooled analysis · 2017
“SHBG concentrations (Fig. 7, panel B) increased after bariatric surgery in the 189 women (22.2 pmol/l, 95CI 1.6–46.8) and in the 328 men (22.4 pmol/l, 95CI 18.6–26.3) studied, and serum estradiol concentrations (Fig. 7, panel C) decreased in the 46 women (−104 pmol/l, 95CI −171 to −39) and to a lesser extent in the 299 men (−22 pmol/l, 95CI −38 to −7) included in these meta-analyses.”
Prevalence of 'obesity-associated gonadal dysfunction' in severely obese men and women and its resolution after bariatric surgery: a systematic review and meta-analysis. Hum Reprod Update
Who: Severely obese women and men undergoing bariatric surgery; women's estradiol data from uncontrolled before-after studies (mean ages about 31-35, many with PCOS)
PMID 28486593
Five of seven studies agree. In 64 very obese men, weight-loss surgery lowered estradiol. A review of men from 30 countries linked overweight to high estradiol, and a genetic study found higher BMI raised it. Two are mixed. In a Danish weight-loss program, estradiol did not fall as men lost weight.
Computed from 7 studies that test this point, each judged by two readers, in full. 10 more studies are waiting for a full read and do not count yet.
other primary study · 2010
“As expected, BMI was positively related to estradiol levels and inversely related to total testosterone and SHBG levels.”
Body mass index in relation to semen quality, sperm DNA integrity, and serum reproductive hormone levels among men attending an infertility clinic. Fertil Steril
Who: Male partners of subfertile couples at the Massachusetts General Hospital Fertility Center, mostly Caucasian, mean age 36.3
PMID 19261274
pooled analysis · 2017
“SHBG concentrations (Fig. 7, panel B) increased after bariatric surgery in the 189 women (22.2 pmol/l, 95CI 1.6–46.8) and in the 328 men (22.4 pmol/l, 95CI 18.6–26.3) studied, and serum estradiol concentrations (Fig. 7, panel C) decreased in the 46 women (−104 pmol/l, 95CI −171 to −39) and to a lesser extent in the 299 men (−22 pmol/l, 95CI −38 to −7) included in these meta-analyses.”
Prevalence of 'obesity-associated gonadal dysfunction' in severely obese men and women and its resolution after bariatric surgery: a systematic review and meta-analysis. Hum Reprod Update
Who: Severely obese women and men undergoing bariatric surgery; men's estradiol data from uncontrolled before-after studies (mean ages about 31-51)
PMID 28486593
other primary study · 2009
“Weight loss through gastric bypass surgery was effective in reducing serum estradiol levels (37.7 ± 10.1 to 29.6 ± 7.0 pg/ml; P = 0.003) and increasing both total testosterone (314.9 ± 201.0 to 625.8 ± 185.6 ng/dl; P < 0.001) and free testosterone (57.6 ± 20.3 to 102.8 ± 20.0 pg/ml; P < 0.001) levels.”
Effect of Roux-en-Y gastric bypass surgery on the sex steroids and quality of life in obese men. J Clin Endocrinol Metab
Who: 64 severely obese men (mean age 48.9 yr, mean BMI 46.2) from the Utah Obesity Study: 22 had Roux-en-Y gastric bypass, 42 controls
PMID 19174499
pooled analysis · 2021
“Overweight and/or obesity were also positively associated with high estradiol concentrations.”
Male adiposity, sperm parameters and reproductive hormones: An updated systematic review and collaborative meta-analysis. Obes Rev
Who: Men aged 16-66 years from 30 countries in observational studies of adiposity (mostly BMI) and sperm/reproductive hormones
PMID 32705766
other primary study · 2022
“While in women, obesity was associated with hyperandrogenism, genetically instrumented raised BMI in men was causally linked to low BioT and raised E2 levels.”
Sex hormones, adiposity, and metabolic traits in men and women: a Mendelian randomisation study. Eur J Endocrinol
Who: European-ancestry adults, genetic instruments from UK Biobank GWAS of up to 425 097 participants; sex-specific outcome GWAS data; male oestradiol analyses
PMID 35049520
other primary study · 2011
“Weight loss did not decrease serum estradiol levels.”
Does weight loss improve semen quality and reproductive hormones? Results from a cohort of severely obese men. Reprod Health
Who: Severely obese men (BMI 33-61) in a residential weight loss program in Ebeltoft, Denmark
PMID 21849026
other primary study · 2013
“Nevertheless, a statistically significant association was observed between BMI and EST ( P < 0.01), SHBG ( P < 0.001), and also the TES/EST ratio ( P < 0.001).”
Association of body mass index with some fertility markers among male partners of infertile couples. Int J Gen Med
Who: 159 male partners of infertile couples at Kosar Infertility Center, Urmia, Iran (non-diabetic, non-smoking, non-azoospermic); 85 classed fertile, 74 infertile
PMID 23785240
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