Is soy bad for you? Or is it the best superfood on the planet?
Most people assume eating more soy is good for them, but the truth is muddier than you think.
Eating more plant-based foods in your diet is usually a good thing. Yet, when it comes to soy you’re going to want to think twice.
Every food on the shelves at your local grocery store seem to have some kind of soy derivative in them. But does this make the food healthier?
You’ve heard rumors how eating soy can mess with your hormones and thyroid. It’s hard to tell where the real truth is when it comes to soy being bad or good for you.
The American Heart Association in 2006 recommending eating more soy to improve cardiovascular health. But they ended up reversing this statement in 2008.
And in 2017 the FDA announced it was reversing their claim eating more soy could reduce the risk of heart disease.
There are big bucks behind soy in the U.S. which over 90% of the crop has been genetically modified. They might have some influence on promoting the “benefits” of eating more soy.
I’m sure you’ll agree it’s hard to tell if soy is good or bad for you. After reading this you’ll know the truth about soy with science-backed answers.
Is Soy Really Bad For You? Uncovering The Truth
In the past 50 years, an anti-fat propaganda has pushed soy into becoming the biggest “superfood” in the world.
But when you read between the lines these studies only looked at the correlation and not the causation. So it’s hard to tell if soy was responsible for these benefits.
Much of these original studies have bad research or are influenced by the soy industry. When scrutinized you can tell something isn’t right.
Studies have found eating soy can stimulate the growth of breast cancer cells. It’s hard to recommend eating more soy to women who are at the risk of getting or have had breast cancer.
Soy is a common food allergy that many people in the Western world aren’t even able to eat.
Soy contains estrogen-like compounds called isoflavones. This is a type of phytoestrogen also known as the “estrogen mimicker.”
These phytoestrogens found in soy can activate estrogen receptors in your body.
More studies are finding soy can promote cancer cell growth, impair female fertility and even mess with thyroid function.
The majority of soy produced in the U.S. are from genetically modified sources.
It’s best to steer clear of soy that has been processed. Processed soy is acid washed and placed in leaching aluminum tanks with high-temperature heating.
Soy has one of the highest pesticide contaminations of any other crop in the world. Most processed soy also has added artificial flavoring to improve the flavor of it.
But soy isn’t all bad in all situations. There is some soy that is actually one of the healthiest foods in the world for you.
Experts are still confused about if soy is bad for you. Some moderation seems to be okay, but it’s best to stay away from soy burgers and GMO soy cheese.
Soy Makes You Fat
Many processed foods that have soy added to them are a lot worse for you than you think and can even make you fat.
Food manufacturers put soy oil in millions of products. The sad part is most people don’t even know they’re eating it.
In this 2011 study, researchers found the consumption of soy oil has increased a thousandfold over the past hundred years.
This heavily suggests eating more soy in the diet has become the most rapid diet shift in all human history. Many researchers are speculating eating so much soy is in large part responsible for the big increases in obesity.
The study by UC Riverside found soy oil to be more fattening than both coconut oil and fructose.
The mice in the study were eating 40% of their calories from soy oil. Turns out the group consuming soy oil became fatter by 25% than the group eating coconut oil despite calories being equal.
The researchers found the mice being fed soybean oil became more obese, diabetic and had more insulin resistance than the group fed coconut oil.
Soy also contains a lot of polyunsaturated fatty acids. These polyunsaturated fats react easily with oxygen in the manufacturing process resulting in fewer antioxidants and vitamins.
This can cause an oxidative stress meaning you’ll have more inflammation in your body. Oxidative stress is cause you to gain weight and age faster.
Inflammation in the body makes you gain weight faster as your brain tells you to make more fat cells.
Soybean oil is essentially inflammation in a bottle. The oxidative stress caused by soybean oil will brainwash your body into growing more fat cells, and thus make you fatter.
Soy Boosts Estrogen (Kills Testosterone)
The isoflavones in soy can mimic estrogen in your body. There’s evidence finding these estrogens can contribute to the growth of tumors in the breasts, endometrium, and uterus.
In rats, exposure to soy isoflavones in the womb can lead to adverse effects on sexual development in males.
In this study 99 men attending an infertility clinic found men eating the most soy for the past three months had the lowest sperm counts.
In all honesty, eating a little soy in moderation isn’t necessarily going to give you man boobs or kill all your testosterone.
But if I were you I’d recommend cutting soy out of your diet.
This 2010 study in Fertility And Sterility suggested soy protein and isoflavones do not affect testosterone levels in men. But when you read between the lines the head researcher in the study also runs a soy company.
Isolated soy protein is much more concentrated form of soy. Soy protein powders are something you should steer clear of for this very reason.
This study found two scoops of soy protein powder decreased testosterone in young males by 19% after four weeks. Their testosterone levels increased within two weeks of getting rid of the soy protein powder.
And in this study, a man drinking three-quarters of a gallon of soy milk all day (which is a lot) ended up developing man boobs. He was able to reverse it when he stopped drinking soy milk.
If you’re drinking Soylent regularly then it’s a good idea to throw it in the trash right now. Most people think Soylent is healthy, but I’d recommend against it.
Most men should stay away from eating a lot of soy. If you already have decreasing testosterone levels then I would definitely keep the soy out your diet.
Soy Can Cause Breast Cancer
Many menopausal women are recommended to eat more soy because it’s a natural alternative to estrogen boosting drugs.
Yet, there are consequences that come with adding so much soy to your diet.
This study found eating soy can decrease the symptoms of menopause in women affected by it. Unfortunately, there are also many negatives that come with eating soy that take away these benefits.
In this study in The American Journal of Clinical Nutrition, they found women consuming soy protein have much higher increases in the number of cells in their breasts most likely able to turn into cancer.
Another study found consuming soy protein by some of the women increased the number of these cells in the breasts that can turn into cancer.
But there are also some observational studies finding women who consume soy had a reduction in breast cancer. The problem with observational studies is they don’t prove soy caused these benefits.
All they do is show a correlation between those who have been eating soy and reduction in breast cancer. They could be doing something else that is responsible for this reduction in breast cancer.
Soy Can Screw With Your Thyroid
Eating soy regularly has been associated with thyroid problems in women.
Turns out soy contains high levels of goitrogens.
Goitrogens are compounds that can inhibit your thyroid’s ability to use iodine correctly. This can lead to having a reduced thyroid (hypothyroidism).
Symptoms of hypothyroidism include:
- weight gain
- slower metabolism
- feeling cold
- hair loss
- weakened & achy joints
- dry & itchy skin
- irregular periods
In this study, researchers found those who were recently diagnosed with hypothyroidism gained 15-30 pounds.
There’s hardly enough evidence to definitely say consuming soy will cause hypothyroidism. But it doesn’t look good.
If you already have thyroid problems or think you might develop them then it’s best to steer clear of any and all soy.
Soy Impairs Fertility
In this 2010 meta-analysis, they found premenopausal women eating soy had a decrease in the two most important hormones for fertility.
In this 2008 study, they found soy’s estrogen-mimicking compounds can reduce the fertility in female mice.
But this long-term study by the Nurse’s Health Study found women eating a larger amount of animal protein were more likely to have fertility problems. They recommended eating more legumes including soybeans to protect against infertility in women.
I would highly recommend against soy in infant formula even though the waters are little muddy when it comes to soy and infertility.
Here’s a study were girls fed soy formula as an infant were much likelier to go through puberty at a younger age.
In this study they found soy formula during infancy can lead to the lengthening of the menstrual cycle and also increased pain in adulthood.
So long story short if you’re pregnant, trying to get pregnant or breastfeeding then you might want to stay away from soy and other endocrine disruptors.
Good Soy: Whole & Fermented
There actually is some soy in the world that is quite healthy for you.
Okinawa Japan is considered to be one of the healthiest places on earth. Researchers discovered they ate a lot of soy. It was only a matter time after that when soy increase in popularity.
But it turns out they also eat a lot of other healthy foods including seafood, green tea and seaweed. They’re also more active and live a healthier lifestyle.
The food industry wants us to believe Asians live longer and are healthier because they eat more soy.
It turns out Asians usually eat fermented soy and not as much as people think.
Japanese women eat a lot of fermented soy and have 1/5 the breast cancer rate of Western women.
Japanese traditionally eat small amounts of fermented soy. This kind of soy is highly beneficial to your body.
Examples of fermented soy include:
You won’t see any soy burgers or soy protein shakes making the list.
The fish broth the Japanese eat in their soup also help counteract some of the negative effects of soy.
Organic fermented soy will not cause any problems in your body. The bacteria in the fermentation process breaks down estrogens.
It’s actually healthy for your body to eat fermented soy as it increases the probiotics in your gut.
Soy sauce from Japan is fermented and is a much healthier option than those produced in the U.S.
In the United States, they take shortcuts to make soy sauce. They don’t go through the traditional fermentation process and instead use artificial methods.
Avoiding unfermented soy is a good idea. The fermentation process will drastically reduce phytic levels in soybeans.
The fermentation process also helps to eliminate the phytic acid in sourdough bread making it a much healthier option to other breads.
Soybeans are also very high in phytic acid which can prevent mineral absorption. This means you will have less calcium, zinc, magnesium, and iron in your body.
Is soy really bad for you?
It really depends who you ask but for the most part I wouldn’t recommend most people to regularly eat soy. While it does have some health benefits there is just too much controversy behind it to recommend eating it every day. With that said if you just eat it once in a while I’m sure you’ll be all right but it’s not something that should be a main staple of your diet.
The Last Word
Even after reading all that it can still be confusing on if soy is bad for you.
Most evidence has found soy is bad for you. It can cause serious problems such as obesity, breast cancer, thyroid problems and even increased estrogen levels.
Just about every study promoting the benefits of eating soy has been sponsored by the soy industry or the researchers have financial ties to the soy industry. That doesn’t necessarily invalidate their findings but it does make it questionable.
Cut the bad soy out of your diet and instead go flat belly foods like the ones in The Flat Belly Formula system. It contains everything you need to live healthier, slim down fast and drop those last 10-15 pounds of stubborn belly fat.
If you have to get your soy fix then eating a little bit is probably not going to kill you. And some controversial studies do find some benefits to it.
Always try to go with fermented soy over soy that has been heavily processed from GMO sources.
Much of the unfermented soy in the U.S. is from GMO sources. This soy is quite high in phytoestrogens that can cause damage to your body.
I steer clear from soy (unless it’s fermented) and will continue to recommend my clients to cut it out of her diet.
Josh holds a Bachelor’s degree in Exercise Physiology and Nutrition Science. He’s a Certified Strength and Conditioning Specialist (CSCS) by the National Strength and Conditioning Association and he’s a Certified Personal Trainer (CPT) by American Council on Exercise. He’s worked as a Strength and Conditioning Coach at the high school and college levels. He has over 15 years of experience as a personal trainer and nutrition coach. He is also the author of The Flat Belly Formula. He strives to bring inspiration and results for people to live healthier lives through smart diet and exercise.