T Nation

Soy for women

I know, here’s another soy question, but I have done some reading on it so be gentle on me :-).
It is generally accepted that soy is not good for males, but what about females as part of their diet. The majority of protein ex dairy, meat and other food sources but having say 1 meal per day of soy? I found this ex JB [quote]If you read the abstract the researchers clearly state that SOY IS AN INFERIOR PROTIEN. It is low in some critical amino acids. Now, if taken in a mixed diet, I think that it can be ok. But I certainly wouldnt want to make it the bulk of my diet. I figure it this way…the research on the whole points to its inferiority for BB purposes so why chance it. If it sucks, then I lose. If it doesnt suck, then cool but its certainly not BETTER than milk proteins or animal. Id rather not take the chance with my development. The evidence points to casein, whey, and animal proteins as better. So Im goin safe and sticking with them. But like I said, I do get some soy in my bars and I do get some in my cereal (VIVE)…the cereal is canadian and contains a nice profile 8g P, 21g C, 1g F. Protein comes from soy. I get about 2 servings of this per day (16g of my 350 come from soy).[/quote]
Admittedly this is 2 years old, and I am wondering what the consensus was.

I wanna know too!
So soy’s not good for men because it increases estrogen…bad for muscle building/fat storage etc. Does it have the same effect in women?

I dunno, but I don’t eat a lot of soy in general, so I don’t really care

However if you’re a big time soy eater, perhaps you should look into it.

The problem with soy is that we don’t have a lot of data about its long-term effects on humans in the quantity and forms it is now being consumed. So assuming the same people consume it, in the same forms, in the same amounts, then we’ll know in 15-20 years the extent of damage. A lot of the soy proponents have been pointing to Asian diets to indicate that soy is safe, without actually researching Asian diets. Throughout Asia, soy represents a VERY small percentage of daily calories (it is a frequent condiment in many places). Additionally, the extent of processing of soybeans and soy products before meals is amazing. Traditional culinary ideas believed that soy had poisons you had to get rid of before eating. (This is actually true to some extent). In the West, we don’t take any of the bad stuff out of our soybeans, soy protein powders, tofu, etc…

Now the current evidence that’s out there in my opinion does not recommend soy for female’s health or muscle gain. It has protease inhbitors which block the digestion of protein, and it’s highly estrogenic, therefore it promotes fat gain, inhibits muscle growth and promotes many kinds of cancer. It also seems to have negative effects on the thyroid and brain function. And it doesn’t help breast cancer AT ALL (in fact, it may assist the growth of breast tumors), and to get the stated cardiovascular benefits you have to consume a lot, and this means increased risk of potential damage. The benefits are rather small for CV health, comparing to adding fiber to your diet; and the benefits for osteoporosis are unsupported in the long-term (in the short term, the research shows benefits in inactive woman on lower-protein diets).

Brian, thanks for that detailed post.

Stella, the question was asked for my wife. She is not a big soy eater at all, just looking for extra ways of getting protein.

There have been three soy articles at T-mag. I think at least one of them talked about why soy was bad for women too. A search will bring them up.

Interestingly enough, I being female actually have negative side affects from consuming too much soy. It causes me to bleed too much (menstration wise) due to it increasing estrogen levels. Also, I have to use a really low estrogen bc pill, so it would make sense that soy would cause similar problems in my case. So, maybe for some soy could be good, in my case too much soy is bad.

We must stop the myth that because something is estrogenic it promotes fat gain. The research literature does NOT fully support this, and there are few studies out there which suggest that estrogen causes fat gain. Rather estrogen is produced in some fatty tissue depots through the functioning of aromatase. Increased estrogen is not related to fat retention at least as far as the research literature is concerned at this point.


Again thanks.
Tek, I had read those articles and most of the info is directed at men and pregnant females in particular. Issue 185 suggested that all women stay away from it but again this was 2 years old (as per the quote in original post).

Teela, thanks for the very personal post.

Vain68, as always a very good objective post.

Vain68, I wasn’t suggesting a direct relationship between estrogen and fat gain. Experimentally, there is often a correlation but not all the time. I only meant that in many cases, when dieting women who are seeing no progress remove estrogen, xenoestrogens and estrogenic substances (like the Pill) from their bodies, their diets suddenly work.

Hey just letting you know everyone is different!

A recent T-mag article (one of Kalman’s maybe?) said that one study showed soy could negatively affect thyroid function. Not good for anyone wanting to lose fat. I assume women wouldn’t want that either.

Teela’s right about everyone reacting differently. My friend who works at a nutrition store knows two women who STOPPED menstruating from too much soy. When they cut the soy, their period came back as normal.

I’m playing it safe. I’m avoiding soy like a vampire avoids sunlight.

this post is with all due respect.

You indicated that experimentally there is often a correlation between estrogen and bodyfat, particularly in women who come off of estrogenic substances like the pill etc.

I have only found one study (done on transexuals) which indicated that estrogenic substances (hormones) led to increased retention of body fat. Other studies have shown that women who gone on HRT actually decrease there levels of visceral body fat…

The reason I ask, is becuase with my particular endocrinological background in adipose tissue metabolism and associated factors, an exhaustive literature review has only revealed one study pointing to this…

I know anecdotally that persons (males) taking aromatase inhibitors have reported loss of hard to get body fat, but this may be due to increased Free T which has been shown to have a marked response on particularly subcutaneous body fat rather (i.e., its not the estrogen that causes fat gain, but rather the loss of otherwise useful free-T).

So soy itself is not the issue, even it contains estrogenic compounds. Its aromatase if anything.

Let me know if you have any cites you can provide me with.


No offense taken, Vain, I know you know this is a complex issue.

O’Sullivan and Brown (2001) saw estrogen decreasing lipid oxidation in premenopausal women and women in early pregnancy.

However, it is absolutely clear that estrogen shifts the site of fat accumulation from visceral abdominal fat–where it appears to be more dangerous–to the hips and buttocks. But paradoxically, even though visceral abdominal fat causes insulin resistance, estrogen replacement therapy may decrease insulin sensitivity. This is where people usually suggest an association between estrogen and retained adiposity (putting aside things like “carb cravings”).

Munoz and Gower sugggest that HRT increases insulin sensitivity in abdominal fat in post-menopausal women who have high amounts of this fat, but decreases it in women with lower amounts of the fat. So if insulin sensitivity is the crux of fat gain for a woman, HRT might assist obesity, except those already obese (and probably already insulin resistant).

Ryan and Nicklas (2002) concluded that “Postmenopausal women taking oral estrogen or those taking a combination of estrogen and HRT are more insulin-resistant than women not on HRT, even when women are of comparable total and abdominal adiposity.”

Also, if I remember correctly, too little estrogen may impair glucose utilization during exercise, but the presence of estrogen has been shown to reduce carbohydrate turnover in animals and humans.

It’s obviously a very complex issue. When I said “correlation” that was imprecise language, so I’ll watch myself next time.