(Most of the studies used non-bio-identical hormones [sigh, and at highish doses], so I've flagged some of them with the following abbreviations: CEE conjugated equine estrogen, the stuff that's in Premarin and MPA = medroxyprogesterone acetate, the stuff that's in Provera. Almost all the studies are on women in natural menopause. And remember, I'm not a medical professional, just a hyster sister with a need to know!)
Does HRT have any effect on weight at all?
There's a war going on between women who are convinced that HRT causes weight gain and the majority of scientists who say that it doesn't. The one thing everyone agrees on is that menopause causes weight gain and changes your body so that, where muscle once was, fat now is. But does HRT help or hurt?
There's one massive study, called the Rancho Bernardo, that has been following 671 women, aged 65-94 years old, who have been on HRT (98% were on CEE.). When they compared these women to the women in the study who never used HRT, the scientists said that there was no difference between them after 15 years. Oddly enough, the women with HRT had started out leaner, so it sounded to me as though they'd actually gained weight, but that's not what the authors concluded, so who am I to argue? There are other studies that support the idea that HRT makes no difference. For instance, a younger group of women, 44-54 years old, took CEE/MPA or no HRT. Both groups gained weight and had a higher percentage of fat. So the HRT made no difference, except that the ones who took nothing were more likely to have belly (bad) fat.
The trouble with this line of thought is that something is happening at menopause that causes us to gain weight and get fatter (lose lean body mass), and since that something involves hormones, it seems that HRT would make a difference.
Does HRT cause weight gain?
To the surprise of the doctors using a very high-tech way to measure fat, the women taking HRT (CEE/MPA/calcium) got slightly fatter (less lean body mass) than the women who weren't taking HRT. It makes sense that HRT increases weight when you think about what hormones are for.
Progesterone promotes fat synthesis and storage since this would contribute to successful pregnancy (it's named for pregnancy--Pro=for: gest=gestation). It's believed to increase appetite, to slow down how fast food moves through the intestines (so more calories get absorbed), and to decrease insulin sensitivity, which can elevate blood sugar so the fetus gets more food. Of course, this all happens at the very high levels of progesterone during pregnancy, not the levels of HRT. In the studies, progesterone in HRT has a moderate effect on weight, at most, probably when it converts to androgens (like testosterone). If the ratio of estrogen to progesterone is in balance, then it doesn't increase appetite at all.
Estrogen promotes sodium and water retention because this increases blood volume, which increases the delivery of nutrients to the fetus. One thing everyone agrees on is that estrogen causes water weight gain when it's not in balance.
Most of these studies involve women taking MPA along with their estrogen. Everyone agrees that the androgens that progesterone can turn into can be a problem. If male hormones are given to female rats, they gain weight while eating only a little more food; If estrogen is given to male rats, they lose weight. Scientists know that weight and food intake are increased by progesterone and decreased by estradiol in rats without ovaries. And cancer patients who aren't eating enough because of the cancer treatments can gain weight when taking MPA, which increases the amount of food they eat.
If estrogen causes weight loss, as so many claim, then it's odd that a high dose of estrogen causes weight gain in adolescent girls with anorexia (eating disorders seem to develop around puberty, so they're exploring the connection with hormones). Of course, there's that other hand--estradiol may trigger anorexia by decreasing meal size because it increases the gut peptides that tells us we're full.
Estradiol may improve glucose among postmenopausal women with type 2 diabetes. Or it might not make much difference, or even have a negative effect. One study of overweight women who already had type 2 diabetes decided that CEE/MPA reduced their waist to hip ratio and central abdominal fat and boosted their metabolism so they burned more calories. Total fat mass, fasting glucose, insulin, triglycerides, and blood pressure, however, didn't change. In other words, HRT might make you healthier if you're already fat by putting the fat on your hips instead of your belly.
Does estrogen prevent weight gain?
Everywhere you turn, there are doctors insisting that estrogen prevents weight gain. The primary source for this opinion is the PEPI (Postmenopausal Estrogen/Progestin Intervention) study. This is a randomized, placebo-controlled study of 788 women across three years, so it's the gold standard for science. In this study, women on the placebo gained more weight than the women on HRT. The placebo group (taking no HRT) gained an average of 4.6 pounds, women on CEE alone gained 1.5 pounds, women on CEE and MPA or CEE and real progesterone gained 2.9 pounds (both of these were taken in a cycle across the month), and women who were on CEE/MPA every day gained 2.0 pounds. So estrogen actually slowed down the arrival of the menopausal Buddha belly, as did a steady balance between the hormones. Other studies support this sort of finding too.
Does estrogen help you lose weight?
It definitely does if you're a rat. Rats without ovaries frantically licked a sugar solution and gained weight until they were given estradiol. The sugar still tasted good but they got full sooner (because estrogen triggered gut peptides that send the full message to your brain), and they stopped licking. When the scientists bypassed the rats' stomachs and injected estradiol right into their brains, the rats ate less (so maybe estrogen affects brain chemistry to help lose weight). After their ovaries were removed, the rats ate dramatically more. As soon as they got estradiol, they went back to eating smaller meals. Their weight loss is even greater when the rats had access to an exercise wheel. Even in guinea pigs, estradiol lowered blood pressure, lowered food intake, and lowered body weight.
Scientists are now pursuing those peptides in the stomach that tell the brain that you're full, especially leptin and cholecystokinin. Levels of leptin, which is part of appetite regulation and energy metabolism, change with body mass and age. The levels also change with estrogen. They've found that HRT had no effect on women with low or normal levels of leptin, but it had a significant weight loss effect on women with high leptin levels. So, like the diabetes study, it can help some women.
Does HRT have an effect on cravings?
It sure seems like it would, but it's not clear what. Forty to 50% of American women crave chocolate or sweets at particular points in the menstrual cycle, indicating a connection to hormones. Half of them specifically have cravings at a time when progesterone drops and estrogen is high, but taking more progesterone didn't stop the cravings. (So maybe it was the higher estrogen levels?)
Oral versus transdermal estrogen
There's a very exciting, but very small, study that shows that the delivery system may make a big difference. Among these 18 women studied, oral estrogen (of various kinds) increased fat mass and decreased lean muscle mass while estrogen from a patch (Estraderm) had no effect (actually there was a slight increase in lean muscle mass, but it wasn't significant).
Both groups got MPA in a cycle. Oral estrogen boosted growth hormone (a chemical that helps build muscle but also messes up insulin and carbohydrate metabolism); it also lowered the insulin-like growth factor-I levels (a chemical that balances growth hormone). It also changed how fats and carbohydrates were processed (not for the better). There are other small studies that show a difference between the two delivery systems. However, oral estrogen has good effects on LDL and HDL cholesterol and transdermal estrogen does not.
Conclusion
So, what's the conclusion? At least for now, I'm stuck next to the German scientists who titled their article, "estrogen-induced weight gain cannot be predicted in individuals." But there are some clear things to try. The first is to deal with the changes that menopause itself brings. Second, do some weight lifting to increase muscle mass and strengthen bones and increase metabolism. Third, get a balance among the hormones so that neither estrogen (with the water retention) or progesterone (with the conversion to androgens) acts up. Fourth, listen to those peptides telling you that you're full with just a little food (try those small low-glycemic, protein-rich mini-meals that Larrian Gillespie touts). And, finally, it might be worthwhile to try the patch or troches if you're taking oral estrogen..
By the way, one study showed that, If you keep your ovaries and have a hysterectomy and don't go through menopause, then you probably aren't anywhere near this particular tangle of hormone jungle vines.
I do have a version with all of the footnotes to the 34 medical articles I looked at, if anyone wants it, just email me at trish@hystersisters.com.
This content was written by staff of HysterSisters.com by non-medical professionals based on discussions, resources and input from other patients for the purpose of patient-to-patient support.
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