In Part 1 of this series, we covered everything but the hormones. But now it’s time for the million dollar estrogen question: do female hormones make it harder for women to lose weight? And if they do, what can you do about it? In this article, we'll look at the pro- and anti-fat effects of estrogen (yes, there are both!), what this means for weight loss, and how diet can affect estrogen levels in various ways.
Women, Estrogen, and Fat Loss
Estrogen is a tricky hormone when it comes to fat loss, and the ideal is a happy medium: going too high and going too low can be equally bad.
On the one hand, normal levels of estrogen are actually very healthy and even good for body composition and overall health:
- Estrogen is insulin-sensitizing. In fact, some scientists have even suggested that estrogen might be useful as a treatment for obesity and insulin resistance/metabolic syndrome.
- Normal estrogen levels are a biological sign that there’s enough food around. When do you think your body will be happier about burning through your fat reserves: in the middle of a famine, or when your food supply is reasonably secure?
- In premenopausal women, estrogen also seems to encourage a metabolically safer pattern of fat distribution (fat located just under the skin rather than packed around the organs). It might not feel like much consolation when you look at the scale, but it’s better to have the extra weight without the metabolic consequences than to have them both.
That’s all good – but on the other hand, estrogen also has a very tangled and complicated relationship with adipose tissue (body fat). Fat cells aren’t just inert blobs of energy storage sitting around on your hips. Actually, fat tissue is a very active part of the hormonal system, and one of its biggest jobs is to produce estrogen. Fat tissue contains an enzyme called aromatase, which converts testosterone to estrogen – estrogen comes from other places as well (most obviously the ovaries), but fat is certainly an important part of the process.
This means that the more fat you have, the more estrogen you’ll have, and it also seems to work the other way around. For example, estrogen overload can exacerbate hypothyroid issues, slowing metabolism and causing weight gain. If that “estrogen overload” comes from obesity in the first place, this can very quickly become a vicious cycle (you’re overweight because you have thyroid problems, and you have thyroid problems because you’re overweight).
It’s also possible that high levels of estrogen promote fat gain by preventing oxidation of fats (using them for energy). This study gives a few pieces of evidence for that theory:
- Women gain fat early in pregnancy (when estrogen levels are high), even if they aren’t “eating for two” yet. This suggests that “more estrogen” = “more calories being stored as fat.”
- Weight-stable women don’t just eat fewer calories than men (as you’d expect, since women are smaller on average); they eat fewer calories per pound of lean body mass. This suggests that women are more efficient at storing calories as fat.
- Women whose ovaries (the major producers of estrogen) are removed lose weight; if they’re put on estrogen therapy, they gain weight.
Remember that these are all perfectly understandable evolutionary design features. Higher estrogen levels during puberty drive fat gain as an energy reserve in case you get pregnant. During early pregnancy, they go into overdrive to “stock up” for the approaching challenge. Your body still hasn’t caught up to the 21st century; it still thinks its job is to keep you (a) alive, and (b) fertile in an environment of extreme food scarcity and a constant threat of famine. So storing extra fat at every opportunity makes perfect sense: back in the day, it could have meant the difference between life and death (or a healthy baby and a miscarriage).
This only starts being a problem when you take a body adapted to scarcity and plunk it into a world of fast food and takeout - which, of course, is exactly what we've all done. That's when the normal and healthy preservation of essential body fat (remember that healthy women need some body fat) goes overboard.
In short: it’s complicated! Clearly, it’s not as simple as “estrogen makes you fat” or “estrogen prevents weight loss.” And like most things in life, there’s a happy medium. There’s a healthy range of estrogen that brings nothing but benefits, but too little or too much estrogen can cause problems. Think Goldilocks: it’s not about demonizing estrogen (or anything else); it’s about finding the balance.
Unfortunately, that balance can be hard to find when our ancient evolutionary responses just aren’t appropriate for the modern food environment. Especially for women who are already overweight, it’s entirely possible that the fat -> estrogen -> fat cycle can spiral out of control. Weight loss by itself approaches this problem from one angle (less fat means lower estrogen production), but specifically addressing estrogen might also be helpful.
Normalizing Estrogen Levels for Weight Loss
Just to be clear: if you’re struggling with a chronic hormonal issue like PCOS, infertility, or amenorrhea your best bet is to go find a good endocrinologist who can run blood tests and give you specific advice. Diagnosing yourself over the internet is not a substitute for a doctor! But while you’re waiting for an appointment, here are some studies that point to possible avenues for normalizing estrogen levels.
Fiber seems to be anti-estrogenic. In this study, raising fiber levels by 15 grams per day (that’s a little less than twice the fiber in one avocado) successfully reduced estrogen levels in premenopausal women.
The available evidence shows that moderate carb restriction is effective in treating any female hormonal problems that might be driving weight gain. In this study of women with PCOS, for example, 30% of calories from carbs worked better than 55% of calories. On the other hand, an extremely low-carb diet is not necessarily the answer either: especially for women, extreme carb restriction can cause problems of its own, including hormonal dysfunction, amenorrhea (loss of normal periods), and infertility. Sweet potatoes are not the enemy! You can eat 1-2 starchy tubers (potatoes or sweet potatoes) every day and still be well under 30% of calories from carbs.
In this study, women were put in one of two groups. Group 1 ate a “normal” diet with 15% of calories from protein. Group 2 ate a high-protein (30%) diet, with a special emphasis on low-glycemic-index foods. Both groups lost weight, but the Group 2 also had impressive hormonal improvements, specifically a decrease in androgens (male sex hormones) and markers of inflammation, and an improvement in insulin sensitivity. It’s complicated because there were two interventions at once (the protein and the glycemic index), but this seems to suggest that getting enough protein is important for hormonal healing.
Fat is important for hormonal health because saturated fat is the backbone of sex hormones (testosterone and estrogen). The usual Paleo advice applies: saturated, and monounsaturated fat is generally good for you; polyunsaturated fat is better limited, and pay attention to getting more Omega-3 and less Omega-6 in your diet.
Summing it up
Part 1 of this series went over some non-hormonal reasons why women might struggle to lose weight, including their lower body mass and unrealistic expectations about thinness and beauty. Part 2 took a look at hormones – specifically estrogen – and what they might have to do with weight loss.
The results: estrogen isn’t an angel or a demon; it’s a hormone that should ideally be within a healthy range, and too much or too little can be dangerous. So far, some studies suggest that a high-fiber, lower-carb diet might be useful in treating estrogen overload, but the best advice for anyone with PCOS or another serious problem will come from a real endocrinologist.
Ultimately, Paleo is a good diet for hormonal imbalance without any fancy protocols or special tweaks. Paleo is naturally high in protein and fiber, and low to moderate in carbohydrates: just what the evidence suggests is beneficial. If hormonal issues are still stalling weight loss even after you've been on Paleo for a while, it’s a sign that something more serious is going wrong – and probably time to go see a doctor about it.