Protein Over-consumption in Ketogenic Diets Explained

picture referencing protein over-consumption with a lot of different meats like chicken, beef, etc

Protein over-consumption is one of the main issues discussed at the Ketogains Group everyday. People are always reading, hearing and/or misunderstanding that eating protein will cause gluconeogenesis and kick you out of ketosis. Tyler Cartwright splendidly refuted the claim that protein supply activates GNG in this post, I recommend you check it out.



So, if protein consumption doesn’t massively increase gluconeogenesis, then two questions remain:

  • Why doesn’t ketogains recommend you eat tons of protein?
  • Why does protein over-consumption lower ketones?

Ketogains Protein Recommendation


Of these questions, the first is easier to answer. The reason we don’t advocate the consumption of tons of protein is because beyond a certain point -arguably somewhere between .8g and 1.2g per pound of lean mass(lbm)- there’s just no benefit. Protein also carries a couple of minor inconveniences: It tends to be expensive and it can cause indigestion. If there were no other reason not to over-consume protein, this would simply be enough.

There is also a minor debate over whether or not protein over-consumption prolongs the adaptation phase (irrelevant if you are already adapted). Also some people argue that it may be sub-optimal for performance, but these are secondary to the previous points: It’s unnecessary to eat more, so there’s no reason to recommend over-consumption.

Protein and lower ketones


The second gets a bit more complicated, and touches on something that Tyler just hinted at in his article. My soapbox is diabetes, and to a lesser extent, obesity… Diabetes has a lot to tell us about blood sugar control and precisely how and why certain food items impact blood glucose.

pancreatic beta cells and ketosisIn type one diabetes, the population of beta cells in the pancreas mostly dies, leaving the alpha cells of the pancreas free to produce tons of glucagon. You see, the alpha and beta cells directly counteract each other in the pancreas, so that when the beta cells produce insulin, it suppresses the action of the alpha cells, and vice versa. This creates a beautiful symphony of blood glucose and ketone body control in the blood of a normal individual, but in a T1 diabetic tons of terrible things happen, and the alpha cells of the pancreas overproduce glucagon with nothing to suppress their action.

In type one diabetes, this leads to the out-of-control over-stimulation of the liver to produce blood glucose through gluconeogenesis and ketone bodies through beta oxidation of fatty acids. But the plot is thickened by the simple fact that there are glucagon-producing cells that are not in the pancreas as well. In fact, there are glucagon-producing cells in the stomach, and they respond to the presence of protein in the chyme (the goo that your stomach produces from the food you eat… and if you want to get very specific, they respond to various amino acids, as well as, apparently, physically solid items in the stomach). These cells do not react directly to levels of blood glucose (whereas the pancreatic alpha cells tend to be suppressed a bit by high glucose levels. These cells do, however, react somewhat differently to protein meals depending on blood glucose levels. It gets very complicated, and the take-home message is to understand that the digestive system is enormously complex and highly regulated.

In a type one diabetic, these cells produce glucagon after a high protein meal. Because there is no population of beta cells to suppress gluconeogenesis, insulin never rises due to this protein meal, and diabetics must be mindful of the blood glucose raising effect of protein consumption.

But in a normal individual, this rise in glucagon is followed almost immediately by a rise in insulin. This is, at first thought, counter intuitive: glucagon suppresses insulin, and insulin suppresses glucagon, after all. But the critical question to be answered here is why? Insulin and glucagon suppress each other because as they leave the pancreas, they impact the populations of alpha and beta cells. But in the circulation, they don’t have this effect. In other words, as glucagon secreted from the stomach due to a protein meal enters the bloodstream, the rise in blood glucose signals the pancreatic beta cells to secrete insulin, and this in turn signals the pancreatic alpha cells to therefore stop producing glucagon. Once the stomach cells are done producing glucagon, insulin is already elevated and GNG effectively stops until the meal is passed and a non-fed state returns (technically, glucagon tends to stay slightly elevated for slightly longer than insulin).

I just want to highlight once again that “highly regulated and enormously complex” aspect of the digestive system: the concentration of these peptide hormones, as well as the timing of their releases, and their varied sources are all critical aspects of their control over your body’s fuel supply.

What this does for GNG is causes a temporarily elevated rate followed by a temporarily suppressed rate. The net impact, according to the research, is essentially nil. But what it does do that tends to make keto-dieters go nuts is temporarily suppress the production of ketone bodies. It does this because elevated insulin has that effect, in addition to effectively stopping GNG. This is probably not an issue, except possibly during the ketoadaptation phase, when profoundly elevated ketone bodies are probably required for various glucose-dependent tissues to remain as happy as usual.

To recap: this long and drawn-out story of peptide hormones is the reason a high protein meal “suppresses” ketone bodies: a protein meal causes a temporary rise in glucagon and a temporary rise in insulin. One of insulin’s actions is to suppress the beta oxidation of fatty acids. The effect here then is to temporarily slow the production of ketone bodies, which can reduce their presence in your blood somewhat. It’s probably not important for anything related to weight loss, except that maybe during the adaptation phase it could impact feelings of yuckiness. For performance, is possible that huge protein meals are a bad idea, but it’s also possible that they aren’t.

protein over-consumption increases glucagon production. Glugacon Molecule shown

Glucagon Molecule

And now we are entering the realm of speculation:

Extra Amino acids fate


If a high protein meal raises both insulin and glucagon, but doesn’t cause a significant net change in GNG, what happens to the extra amino acids?

This is a very good question, and one that I haven’t seen answered effectively in the literature (not that I’ve looked very hard). But there are logical consequences here that lead us to conclusions about what happens. Unless you eat enormous quantities of protein, you excrete the extra nitrogen. The extra protein doesn’t lead to hugely elevated GNG, so it’s very likely that the excesses are simply oxidized for energy in place of the fatty acids, considering that there isn’t extra glucose around, and that the liver isn’t processing quite as much fat as usual. There are a few biological bases for this that seem compelling (don’t trust that, of course). The brain can use only a limited set of fuels, and some of those fuels are amino acids; if glucose is not elevated, and ketone bodies are suppressed, it is unlikely that the brain does not have access to other fuels, else death would be likely, and the entire process would seem to be very risky for a species that likely had to go for certain periods of time in which neither fat nor carbohydrates were widely available (like winter).

Now, this is also a reason why performance might not be negatively impacted by protein over-consumption. If the brain can use amino acids for fuel, then there’s no reason why the muscles wouldn’t be able to continue to run on their usual fuels while the brain relies on this new source. This idea is supported by the fact that there are plenty of individuals on “ketogenic diets” that eat much more protein than is required to achieve the standard Phinney and Volek definition of nutritional ketosis, and are able to perform at a high level in various athletics.

I’d like to conclude by wrapping up a few of the key ideas here.

Number one is that the digestive system is incredibly complex; diabetes is a good tool for telling us how it works, but there are pitfalls associated with surface-level analyses of hormonal shifts and such.

Number two is, of course, that we need to pay very close attention to what diabetes research has to tell us. Without it, we probably wouldn’t even question whether or not there are glucagon-producing cells in places other than the pancreas.

Number three is that you really don’t need to be afraid of protein over-consumption. Eat a reasonable amount, which is enough to maintain/promote the growth of lean mass but not so much that you get digestive problems; for most of us, that means somewhere between about .8g and 1.2g per pound of lean mass. Eating more may not be much of a negative, but it also does not seem to help much, if at all

About Author

Ken Adkins
Keto since 2011 Lifting since 2012


  1. Celeste

    This is all very confusing to me. I am not diabetic but am following a Keto lifestyle. I guess my question is, if I eat more protein than recommended is it going to cause me to not lose weight at the same consistency as I do with eating the set amount? Like instead of eating 75grams, if I eat 115grams is this going to be a problem if I stay under my calorie mark?

    1. darthluiggi

      There is no downside of eating more protein, especially when it is from whole sources (not bars, shakes, etc) – if there is one macro you can eat more, is protein: not fat.

  2. Doug

    I’ve been trying for a while to wrap my head around this subject. Here’s what I think at the moment. Would welcome any feedback on where I am missing it.

    1 – My blood sugar meter shows that my blood sugar goes up 25 points with Protein (50g of whey) for a couple of hours. Not a bad increase since it’s only from 85 to 110 (US units). I have documented this at: .
    2 – My blood sugar drops fairly rapidly at the end of the two hours (makes me hungry) which decreases when the blood sugar levels out. As long as I keep that in mind and keep food out of reach in that time frame I am OK. Otherwise, it seems like my body is telling me that it wants is ready to eat more Protein (or just food).
    3 – Blood sugar production proceeds at a constant rate which isn’t all that much affected by Protein consumption. I’ve seen enough studies to believe that is probably the case such as Also, the demand vs supply GNG argument seems strong. This rules out the idea of GNG being increased by the Protein.
    4 – In a non-diabetic blood sugar doesn’t rise as much with ingested Protein as it does in a T2 Diabetic. It may not raise at all. I plan on an experiment with a “healthy” friend to confirm this for myself although the studies say it is “minimal”. But is that difference due to broken Insulin Resistance in the T2 Diabetic? As the Insulin goes up to deal with the Protein does that increase the Insulin Resistance of the cells at the same time and block the glucose from being consumed?
    5 – The failure for a T2 Diabetic seems to be able to reduce the production of glucose in response to consumption of Protein (or one of the downstream aspects of the consumption). The Glucose (argued above) is getting “backed up” in the process and not being disposed by Insulin since the Insulin is “busy” dealing with the Amino Acids (all in all a very good use of Insulin).

    So although arguably Protein doesn’t turn into glucose directly since Protein does lead to a rise in Blood Sugar (in T2 Diabetics) then what difference does it make if it is increased levels of GNG or an inability to reduce the rate of GNG or due to Insulin Resistance? Either way, the result is the same, Blood Sugar goes up (for T2 Diabetics) with protein consumption.

    So then the question for me is whether or not Blood Sugar going up by a relatively small amount in a keto dieter who is eating lots of Protein actually a problem? Normally, us diabetics are trained to do things to minimize their blood sugars. This notion is leading a lot of people to eat a lot of fat and less Protein than they probably should.

    Put another way, does the advantage of eating more Protein (maintain or growing Lean Body Mass among others) outweigh the disadvantage (marginally higher blood sugars for short periods of time)?

    1. darthluiggi

      Yes. To not go in circles, the more muscle mas you have, the more carbs you can consume (not telling you to eat more carbs) – lean mass is a “Buffer” and helps with insulin sensitivity.

  3. Damien

    Does having fat with the protein meal affect the insulin spike possibly reducing the spike

  4. Amy Reynolds

    So will an increase in blood glucose and reduction in ketones take me out of a fat adapted state and lower my chances of weight loss. I realize the issue is important on my levels beyond this question, but my current interest is weight loss and reducing insulin resistance. Thank you for your time.

    1. Rick Passmore

      No, weight loss is primarily energy deficit, protein will not negatively effect your insulin resistance/sensitivity.

  5. Danielle

    I get what you are saying about T1s. What about T2s then?

  6. Jason

    I have to share my contradictory anecdotal story here.

    Maybe I’m an outlier, maybe I’m metabolically broken, I just don’t know. But when I consume too much protein, my blood glucose goes UP and my ketones go DOWN. I’ve measured this multiple times. I don’t know why you guys at KetoGains are so against a moderate protein diet, but not everyone can pound back the steaks and stay keto!

    1. Tyler Cartwright

      I don’t think you’ve really looked at our recommendations, as they are well within what we (and many others) consider moderate. Further, no one is disputing ketone levels decrease and BG goes up. The dispute is whether this is because the protein you just consumed is being rapidly converted to glucose. The evidence from human trials is “no.” Your anecdotal evidence is the same as most folks…but that ketones go down and BG increases is only proof of correlation, not causation.

      And – we are advocates for rationality and science, not zealotry. The science doesn’t substantiate the “more protein = more glucose” position, and so we have explained why it doesn’t in these two articles.

    2. Rick Passmore

      There’s a very simple explanation to this if you can look past the blinders of protein turning in to glucose.

      Higher protein intake, which needs insulin response to get it where it needs to be, will increase physiological insulin resistance (adaptive glucose sparing) in order to get the protein into where it needs to go without pushing more glucose into the cells. this will result in seeing a higher fasting blood glucose, and lower circulating ketones, as they replace glucose as a fuel for the tissues that previously used more of it.

      Again, no one here advocates high protein diet, it’s all about context. What you are experiencing is normal, but is in no way a cause for alarm.

  7. Matt

    Another good write up on the same topic:


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