Last year, I went about a month eating a block of tofu every single day. It was pretty enjoyable, actually, and it seemed to help my strength training. But I eventually decided to cut back. Why?
In this post, I’ll share the research that made me decide to limit my tofu consumption a bit. I’ll address issues with hormones, IGF-1 (and cancer risk), and more. I’ll end the post with a list of other high-protein vegan foods to consider adding along with tofu!
How Much Tofu a Day Is Safe?
Between 3 and 5 servings of soy per day is believed to be safe and beneficial based on current evidence. This equals about 9 to 15 oz of tofu per day (255g to 425g). Soy consumption above that amount may increase IGF-1 hormone levels, potentially increasing cancer risk.
I’ll share the actual research behind those “safe and beneficial” numbers below. But first, let’s answer the question of what this means for eating a block of tofu a day.
Converting the above serving sizes into “blocks” of tofu is a bit tricky. Tofu blocks can vary in size between brands and in different parts of the world.
Personally, I live in the United States, and most of the tofu blocks I see here are between 12 oz and 16 oz. So most of these tofu blocks contain 4 to 5.3 servings of soy.
This means eating a block of tofu daily may put you near the top of the “safe and beneficial” range. But what does this really mean? What are the actual risks of eating too much tofu?
The Risks of Too Much Tofu
There are a few potential risks from eating too much tofu:
- 1. Hormone issues: You may have heard about soy’s effects on estrogen. Some men are scared to eat soy at all, for fear of growing “man boobs.” These fears are generally overblown, but soy phytoestrogens can affect you negatively if you eat too much.
- 2. IGF-1 levels: Insulin-like growth factor 1 (IGF-1) is a hormone associated with cancer growth. One of the reasons vegan diets decrease cancer risk is because most plant protein doesn’t raise IGF-1 levels, while animal protein does increases IGF-1. That said, too much soy protein can also raise IGF-1.
- 3. Allergies and intolerances: Soy is a common allergen. So if you happen to be someone with a low-key soy allergy or intolerance, eating a full block of tofu per day could obviously cause problems—digestive or otherwise.
You may hear a whole list of other accusations against soy, too—from GMOs, to protease inhibitors, to uric acid, and more. Personally, I haven’t found sufficient evidence to really be concerned about those other issues.
For me, the potential issues with “too much soy” are hormones, IGF-1, and allergies. So let’s take a deeper look at each of those below.
1. Hormone Issues
Soy contains a phytoestrogen (plant estrogen) known as genistein. You may also hear this referred to as an “isoflavone.” It’s generally a very healthy component of soy, at least partly responsible for soy’s cancer-preventing effects.
But are there risks of getting too much genistein? As a phytoestrogen, how does it affect our actual estrogen levels? Can it give you man boobs?
It is possible to get too much soy phytoestrogen… but you’d have to eat a LOT of tofu before it would be a problem.
There are two cases in the medical literature of men experiencing “feminizing effects” from too much soy. But these men were each consuming about 14 to 20 servings of soy per day. That would be 3 to 4 whole blocks of tofu per day.
Generally speaking, the levels of phytoestrogens in soy are a good thing—not a bad thing. Sure, don’t go eating 3+ blocks of tofu per day… But the effect of soy on IGF-1 levels may be the more relevant concern for realistic soy eating patterns. So let’s cover that now.
2. IGF-1 Levels
IGF-1 stands for “insulin-like growth factor 1.” As the name suggests, it’s a hormone similar to insulin, and it make our body grow. Some people view this as a good thing (for muscle growth). But more IGF-1 can also promote cancer growth.
One of the benefits of switching to plant protein is that it doesn’t seem to raise IGF-1 levels like animal protein does (source). However, soy protein seems to be an exception.
For better or worse, soy is the plant protein most similar to animal protein. It contains all the essential amino acids, and it’s considered one of the more effective plant proteins for building muscle… But if you eat too much, it can also raise IGF-1.
So, how much soy do you have to eat to raise your IGF-1 levels? Well, there’s only a handful of studies on that question so far. But Dr. Michael Greger put together this analysis which offers a tentative answer.
He concludes that 3 to 5 servings a day of soy should be low enough to still confer the benefits of eating soy. Above 5 servings, it’s harder to say if the risks cancel out the benefits. This is why I recommend limiting yourself to 3 to 5 servings a day (1 block of tofu or less).
Keep in mind: Even at 5-10 servings or more, soy may still be neutral from a health perspective. It’s not until 14+ servings that feminizing effects from phytoestrogens become a documented possibility for men.
Still, I’d limit soy to 3 to 5 servings per day to be safe. There are other foods you can eat if you need more plant protein.
3. Soy Allergies and Intolerances
This one will not be an issue for everyone. But if you’ve got some kind of soy allergy, intolerance, or sensitivity… then of course, you don’t want to be eating a whole block of tofu a day!
Now, you might be thinking, “Um, I think I would know if I had a soy allergy.” But hey, sometimes allergies develop later in life. And sometimes food intolerances can be subtle.
To share a personal anecdote—only in the past year did I realize some subtle allergic effects when I eat peanut butter. So it happens.
Just keep this one in mind before dramatically increasing your soy consumption. Maybe start gradually and make sure you feel good, before adding too much tofu at once.
Summary of this section: If you don’t have a soy allergy or intolerance, then IGF-1 levels are your main concern. Stay below or within the range of 3-5 servings of soy (~1 block of tofu) per day to get the benefits of soy without likely raising IGF-1.
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My Personal Experience: Eating a Block of Tofu a Day
I’ve had a few periods in the past where I ate a block of tofu just about every day, for a month or more at a time. I would typically eat it as scrambled tofu, all at one meal. My tofu blocks were about 14 to 16 oz, so that was about 5 servings of tofu a day.
I did not notice any negative effects of eating that much tofu. In fact, I noticed one positive effect: My weight-lifting went better! (Probably because I was getting so much more protein each day.)
Since doing this myself, I learned about the IGF-1 issue (explained above). Nowadays, I eat tofu a bit less, and I mix up my protein sources more. (See a list of high-protein vegan meal plans here.)
But I did feel like the added protein helped my strength training. Specifically, I noticed this when I was cutting (eating in a caloric deficit). Prior to adding the tofu, my strength had been stuck at a plateau for a while. After adding the tofu, I started progressing with my lifts again.
That said, I don’t think tofu or soy are a “magic ingredient”—other forms of plant protein would have also worked. Pea protein is another great kind of plant protein for building muscle. Lately, I’m just eating a lot of beans and lentils.
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How Many Times a Week Can I Eat Tofu?
To reduce the risk of elevated IGF-1 levels, limit your tofu consumption to 3 to 5 servings per day. Eating tofu on a daily basis appears to be safe and beneficial within those amounts.
Other High-Protein Vegan Foods
If you’re trying to limit your tofu consumption for any reason, check out the list of high-protein vegan foods to consider below.
I’ve listed a bunch of mock meats and “meat substitutes” from lowest to highest protein per 100 calories. I like measuring this way because then you can get a lot of protein without using up a ton of your calories for the day:
- Beyond Burgers have ~7.4 grams of protein per 100 calories.
- Gardein Crispy Tenders have ~7.8 grams of protein per 100 calories.
- Impossible Burgers have ~7.9 grams of protein per 100 calories.
- Butler Soy Curls have ~9.2 grams of protein per 100 calories.
- Tofu has ~10.0 grams of protein per 100 calories.
- Gardein Beefless Burgers have ~10.8 grams of protein per 100 calories.
- Tempeh has ~11.3 grams of protein per 100 calories.
- Boca All American Veggie Burgers have ~13.0 grams of protein per 100 calories.
- TVP has ~15.0 grams of protein per 100 calories.
- Gardein Plant-Based Jerky has ~15.0 grams of protein per 100 calories.
- Boca Original Vegan Burgers have ~18.6 grams of protein per 100 calories.
- Seitan has ~20.2 grams of protein per 100 calories.
Disclaimer: When it comes to the general products like seitan, tempeh, and tofu, the exact amount of protein may vary by brand or recipe.
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