Are you concerned about getting too much protein on keto? Well first off, you may want to know why this is an issue.

Protein is essentially a string of of amino acids. Through a process called gluconeogenesis, we convert some of these amino acids into glucose. Consequently, it’s not out of the realm of possibilities that you could eat too much protein if yourgoal is to maximize ketones.

But realistically, this is only a problem for people doing a therapeutic ketogenic diet for something like epilepsy. Where we get into problems is when people co-opt the therapeutic ketogenic diet for weight loss. Then, as with every dietary tribe, people start as total purists and slowly drift towards a more balanced approach.

If you guide your decisions based on blood ketone levels, too much protein can kick you out of ketosis. But the problem is, who cares? If you’re losing weight you shouldn’t care about ketones; you’re definitely making them, they just may not accumulate in your blood.

Ultimately, you should worry less about what you call your diet. Instead, focus more on whether or not it’s effective for your goals. Generally speaking, higher protein is both satiating and helps maintain muscle mass. Therefore, restricting it is probably not a great idea for weight loss.

If one of your goals is to maintain a healthy gut, keto may not be for you, at least not the therapeutic ketogenic diet.

Therapeutic ketogenic diet and short chain fatty acids

A few weeks back we discussed a review paper on bias in gut health research. In it, the researchers discussed how our microbiome is metabolically flexible. As a result, the idea that lower carbohydrate diets are bad for the gut because they decrease short chain fatty acids is erroneous. You can check out our coverage of that paper here.

People on social media took this as proof that people eating a ketogenic diet make ample short chain fatty acids. Unfortunately, this paper isn’t proof of anything. It’s simply presenting evidence that there are microbial pathways of protein fermentation that make short chain fatty acids.

That’s quite a bit different than showing enough amino acids make it to the colon and get converted to SCFAs on a low carb diet. A new paper found quite the opposite for those eating a therapeutic ketogenic diet.

In this paper, researchers found a 55% reduction in total SCFAs in people, mostly children, transitioning to a ketogenic diet to manage epilepsy. Furthermore, they found a 33% decrease in butyrate and 50% reduction in isobutyrate. (To see why this is important, check out the blog above)

Why this occurred is pretty clear. Carbohydrate and protein intake dropped from 130g to 20g and 56g to 36g, respectively. Since our microbiome uses both to make SCFAs, cutting both leads to a drop in SCFAs.

Working around too much protein on keto

The consequences of too much protein on keto for someone using it for epilepsy vs weight loss are different. If higher protein intake kicks people with epilepsy out of ketosis, they may experience seizures. But what about weight loss?

If anything, higher protein intake promotes weight loss and maintains muscle mass. So if that’s your goal, worry less about your protein intake or blood ketone levels. Use your weight as your primary goal.

But what if you want to maximize SCFA production in the gut while performing a lower carbohydrate diet? Ultimately, you want enough protein to makes its way into the colon.

You can do this a couple of ways. First, you can increase your protein consumption. Second, you can consume protein with lower digestibility that actually makes it to the colon.

The most bang-for-your-buck approach is to diversify your protein sources. As far as protein sources go, most people focus strictly on animal-based proteins for their bioavailability.

If you only look at protein from a muscle mass perspective, this makes sense. But if you look at it from the perspective of the microbiome, including more plant-based proteins is a good idea.

Plant proteins are not digested as well as animal proteins. Therefore, they are more likely to make it to the colon for fermentation and production of SCFAs.

One is not better than the other. They are different tools for different jobs.

The drawback of focusing solely on animals for your protein needs

Since we have 2 choices, why not just eat more animal protein? For one, there is some evidence that replacing animal protein with plant protein leads to better health outcomes. Note: This study and many others have no conflicts of interest and show the same thing.

Of course, many will jump to the “healthy user bias”. This is the de facto “it doesn’t confirm my narrative so it has to be wrong” excuse. But, not all healthy people do the exact same thing. Furthermore, there are far more overweight and obese people than healthy users to skew the results.

Plus, there are concrete reasons why too much animal protein may not be great for your colon. The primary one is delivery of excess sulfur to the colon.

Animal-based proteins, particularly muscle meat and eggs, are high in the sulfur-based amino acids methionine and cysteine. Dietary sulfate absorption is saturable, and any in excess of what we can absorb will make it to the colon.

Why is this bad? Depending on the context and the individual’s microbiome, this could increase colonic hydrogen sulfide(H2S) to toxic levels. As a result, cells in the colon prioritize H2S detoxification and inhibit butyrate oxidation. So even if you make sufficient butyrate by consuming the proper amino acids, you won’t get the benefits from it.

Even the authors of the pro-low-carb-for-the-gut review note this as a problem.

Which plant proteins should you focus on?

So, if you want to increase your plant protein intake, which sources should you aim for? Ultimately, the best options are whole foods such as nuts, seeds, and legumes.

Stay away from ultra-processed versions such as the meat substitutes currently being made in a lab. And since we’re looking for decreased absorption, plant-based protein powders are probably not the greatest idea unless you are vegan.

Of course, vegans also have to worry about combining plant proteins since they’re not eating meat. But if you’re an omnivore, you probably don’t have to worry about that.

Consuming soy is fine, but wouldn’t be the direction I would go as the primary plant protein source for omnivores. Soy is pretty high in sulfur for a plant-based protein, so other options are better for an omnivore. Include it, but don’t just start eating a ton of soy.

I know people for some reason think soy will crush testosterone or push up estrogen. But this has been studied in humans multiple times(source, source) and determined to be unfounded. This is likely due to soy isoflavones binding to estrogen receptor beta in the gut, which provides a beneficial effect, and being poorly absorbed.

Conclusion

Most people doing a ketogenic diet don’t have to worry about getting too much protein on keto. While this may be a problem for people doing a ketogenic diet for therapeutic purposes, people using it for weight loss likely have nothing to worry about.

In fact, if your goal is to lose weight, more protein is likely better. But if you’re still worried about getting too much protein on keto because you want to maximize ketosis, diversify your protein sources.

Include more unprocessed high protein plant-based foods such as nuts, seeds, and legumes. In addition to increasing short chain fatty acid production, it also decreases sulfur delivery to the colon. Overall, this will promote a healthier gut and microbiome than a strict focus on animal protein.