Weight Gain and the Estrogens in Milk - My Experience

by Nils Osmar. February 4, 2022

I lost over 25 pounds of body fat between the fall of 2020 and the fall of 2021 after starting a health regimen that included dietary changes, new supplements, weight training ad fasting. But I started regaining some of it last fall, around the time I added milk back into my diet.

I’ve been “on and off” about milk for many years. There was a time when it was one of my staples. Then I found that (for me) there were benefits in avoiding it, including less bloating and nasal congestion.

After avoiding it completely for a couple of years, I added it back as an experiment last fall to see what effect it would have on my body. I don’t drink it from the bottle, but I’ve been using it to make yogurt(s); eating fresh and aged cheese. I’ve also taking whey powder in the hopes of raising my glutathione levels. The milk, cheese and whey have all been from milk from organic grass-fed cows ethically raised on small family farms.

So what happened?

My Weight Went Up

After five months of including milk products in my diet, my weight has gone up over 10 pounds (i.e., I’ve gained back 10 of the 25 pounds I lost). Some of this weight is muscle (I’ve been working out intensely and made visible muscle gains), but some is fat, and has been accumulating in my belly area where it was before.

I also found, perhaps not coincidentally, that my mood was going downhill a bit during this period of time.

Higher blood glucose and insulin can also be factors driving fat gain. But according to my last A1C test, my blood glucose levels are fine. And nothing else in my diet or supplementation regimen has changed very much. (I’m eating more mushrooms, but I’m sure that’s not making me gain weight.) And my calorie intake hasn’t changed, because I ate fewer calories from other sources when adding the milk.

So I suspect the culprit really is the estrogens in milk.

Can Cow’s Milk Raise Estrogen in Other Animals?

In theory, estrogen from cow’s milk shouldn’t have much of an effect on hormone levels in other species. The dairy industry has promoted studies suggesting that bovine estrogen can only affect cows. Some studies, like this one, suggest there is no effect in mice.

But this conclusion is contradicted by other researchers. According to this study, the estrogen from milk from cows does (1) raise estrogen levels and does (2) lower testosterone levels, particularly in male mice.

According to this study the effect also occurs in humans:

“The present data on men and children indicate that estrogens in milk were absorbed, and gonadotropin secretion was suppressed, followed by a decrease in testosterone secretion. Sexual maturation of prepubertal children could be affected by the ordinary intake of cow milk.”

So the studies don’t give a clear answer. But they suggest that the mantra that cow’s milk is a good food for humans, which is often repeated by the dairy industry, may not be the whole story. It may be that milk is a good food for those who want to gain weight, but not those who want to keep it even or lose it.

Cheese Concentrates the Hormones

When milk is made into cheese, the hormones become even more concentrated (assuming that it’s full fat). According to this article (quoting a committee of physicians) the more concentrated bovine estrogens in cheese may present a danger of increased risk of breast cancer:

“Dairy cheese contains reproductive hormones that may increase breast cancer mortality risk.
“That’s the warning label the Physicians Committee for Responsible Medicine—a nonprofit with more than 12,000 doctor members—is petitioning the Food and Drug Administration to require cheese manufacturers to prominently display on all dairy cheese products. The petition is being submitted on Oct. 3, as Breast Cancer Awareness Month begins.
“Dairy products contain traces of estrogens from cows, and as milk is converted to cheese, the estrogens are more concentrated. While they are only traces, they appear to be biologically active in humans, increasing breast cancer mortality...”

I’ll be Testing It

My adding cows’ milk and whey back into my diet was a test. It did result in my gaining body fat. I had thought the whey I was taking might increase the rate at which I’m adding muscle, but I haven’t seen evidence that this is true. I’m still gaining, but not faster than I was before.

This is purely an n=1 test of course, but I’ll be starting a new regimen today which excludes milk from animal sources in all forms for at least three months. This means no cheese, heavy cream, cow’s milk or whey powder during this stretch of time. (I may take a teaspoon or two of yogurt now and then for its probiotic benefits, or with supplements that are better absorbed in the presence of fats, but will stop using milk, cheese, cream, yogurt or whey in larger amounts).

I’ll be documenting the experiment with photos and videos and using a scale that gives approximate percentages of body fat and muscle to clarify the results.

Another interesting test would be to try using low-fat or no-fat dairy instead of full-fat (because the estrogens are mainly in the fat). I may try it in the future.