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I'm on a ketogenic diet and have stopped taking protein shakes (excepting post-workout protein powder with water) because I've heard that it may cause an insulin spike. Is it true that protein powder with water will knock you out of ketosis? The one I'm using in particular is Optimum Nutrition Gold Standard 100% Whey.

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I don't think insulin is a problem for your ketosis, but the glucose definetly is. – Sebas Feb 7 '13 at 21:00
Nick, Have you tried Ketostix® or other brands of ketone test strips? They are available at many pharmacies and not too expensive, a pack of 50 lasts many months and costs about $10. You can measure your ketosis level by the matching the color on the strip vs. the test chart on the package, and it takes about 20 seconds to take a measurement... Measure it, and then you will know, whenever you want to know. Do your own biology experiments for fun and edutainment. — A ketosis junkie – GeoFan49 Nov 25 '13 at 23:37
I'm wondering about this, too. Isopure is zero carb, zero sugar, and contains 50g of protein. I find it hard to eat the daily amount of protein I need, so I was thinking about using this powder. Obviously though, my goal is to stay in ketosis. Would drinking this (even half a serving) knock me out of ketosis? – mdegges Feb 12 '14 at 16:22

8 Answers 8

up vote 1 down vote accepted

Yes it can.

Protein is made up of seven different aminos, some of which (just as j.rightly correctly pointed out) can knock you out of ketosis because they are broken down into glucose in your blood.

j.rightly is corrct. Do some research and it will confirm that protein can knock you out of keto. Anyone who says it can't doesn't understand the science behind it.

That is why you are meant to eat about 65% of your diet from fats, 30% protein and no more than about 5% carbs (which will be incidental from your fat & protein based meals) to be sure you stay in ketosis.

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Explain how an increase in insulin results in an increase in blood sugar which would disrupt ketosis. I think you're the one who doesn't understand the science. Insulin != blood sugar. – jcollum Apr 24 '12 at 19:19
the amino acid is broken into glucose if excedentary, then reactively inducing an insuline secretion. – Sebas Feb 7 '13 at 20:59
@MattyP - When you say that protein is made up of seven different aminos, are you referring to every source of protein? Or just whey? – Alec Jan 13 at 7:29


Ketosis is the deprivation of carbs. High end protein shakes, such as your ON Gold, don't contain many carbs. Thus, drinking your protein shake won't remove you from your ketogenic state. On the other hand, cheap proteins (Muscle Milk) and any protein labeled as "mass builder" will contain carbs to prevent ketosis.

Your comment about protein shakes spiking insulin is wrong. Insulin is secreted to process sugar. Your ON Gold with water has hardly any sugar. Thus, drinking your protein shake will not spike your insulin. Insulin spikes usually only occur when you eat simple carbs from fruit, candy, etc...

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-1 for an incorrect answer. Ketosis occurs when the body breaks down fat. When blood sugar is raised, even if due to excess protein consumption, ketosis may stop. This is why the Atkins diet specifically limits the amount of protein meats you can consume in a meal (6-8 oz generally). – Ben Piper Jan 26 '12 at 20:10
+1 for answer. @j.rightly You're confusing insulin with blood sugar. I've been reading about this today and yes, protein does cause an insulin response. The theory is that this is so that aminos will be transported into cells. However I've never heard of insulin disrupting ketosis. Insulin in the blood does not equate directly with glucose in the blood. – jcollum Apr 24 '12 at 19:23

Yes they can, even the one's that have zero carbs. With no carbs a protein powder will not raise your blood sugar, but it can and will cause an insulin spike. This is your body's way of coping with no carbs and it allows your cells/muscles to absorb nutrients from food, and also helps the liver create glucagon from the protein. When you body takes in virtually NO carbs, it still needs to control and regulate your blood sugar and also create enough energy that your body can still survive and allow you to be active. The process is described better in this article... and more info here...

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Are you really citing an article by some Jane Schmoe on the net that concludes with a paragraph replete with "you should be" and "may be" and "I think"? -1. – JohnP Aug 16 '12 at 22:36

From my personal experience: yes, whey isolate can kick you off the ketosis. It happens with me this week; I feel fatique although I eat enough, and ketostix became negative. I drunk 60g of whey isolate three days in the morning (Monday, Tuesday, and today is Wednesday)

It boosts insulin (or something else; and it doesn't matter what); in fact, I don't feel as energized as I was during weekend.

It is third time when I am on ketogenic diet in my life (during past 15 years); first time I was drinking-eating raw egg whites (20-30 a day) and eating meat etc; second time meat; and now I was drinking protein shakes too in the morning, instead of breakfast.

I read in few different sources: main idea behind ketogenic diet is not "low carbo"... indeed, it is "do not eat unnatural food", do not eat grains, sugar, _protein_powder_, anything whichever is unnatural to millions-years history of humans.

I am on ketosis 18 days; I lost about 8-9 pounds, and about 1 - 1.5 inches. However, most weight loss (4-5 pounds) happened in first two days; and now everything stopped (although I do not eat any sugar! I even replaced my BCAA powder which had some maltodextrin) - now I know where the problem is...

Yes, insulin is spiked to process sugar, and not protein. And, body can generate glucose from protein. Someone posted here: "Glucose is the bodies preferred fuel - the body can convert 100% of carbs, 58% of protein & 10% of dietary fat into glucose."

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May I ask what dietary recommendation led you to consume 20-30 raw egg whites a day? (Especially since the yolk has most of the nutrients, and also almost doubles the protein content). – JohnP Feb 6 '13 at 22:29
I was in another country where eggs were 10-100 times cheaper than imported protein; and at that time pure protein was unavailable. I consumed about 5-6 egg yolks a day, plus 20-30 egg whites. You can get intoxicated if you drink 30 yolks :) – Fuad Efendi Feb 6 '13 at 22:39
At that time, about 1996, I read an article about Shawn Ray (bodybuilder). Before competition, two-three months in advance, he goes total "ketogenic", and what he eats is... 4-5 kilo of fish! He is amateur fisherman, check his video: – Fuad Efendi Feb 6 '13 at 22:51

If you consume excess protein on a ketogenic diet, several of the amino acids will be converted to glucose via the gluconeogenic pathway thus knocking you out of ketosis.

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Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.

Do you have any sources to back that up? – Eric Kaufman Jan 12 at 19:13
@Eric Kaufman There are currently no sources that I could find in "man" regarding the effects of protein content on a ketogenic diet, but there is certainly some evidence in rodents. See here – user13637 Jan 13 at 2:42

It' all a matter of the ratio of fats protein and carbs there is a simple calculator on this site where you just enter the grams of each macro and you get the ratio. Any ratio 2 or above, will put you in ketosis. You can do it for each meal or by the day.

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Yes, whey protein can knock you out of ketosis. It has had that effect on me several times. To those who say, no carbs, thus no effect, you're only looking at half the story. Carbs effect ketosis by affecting insulin.

Ketosis is governed by the insulin/glucagon ratio (I/G ratio) (1). Whey has no carbs, has but it IS insulinogenic (e.g., ref (2)) Increased insulin throws off the insulin/glucagon ratio (I/G ratio) (1), which can effect the depth of ketosis.

(1) The Ketogenic Diet: A Complete Guide for the Dieter and Practitioner, Lyle McDonald, 1998, pp. 24, 30-31.

(2) The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on β-cells, Albert Salehi, et al., Nutrition & Metabolism 2012, 9:48:

Whey protein increases postprandial serum insulin levels. This has been associated with increased serum levels of leucine, isoleucine...

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While this question already has an accepted answer, I think I can shed some more light on this matter (with actual science, not just my opinion)...

Here's one of the rare few studies ( that provides a good insight into the influence of (simple) carbs, aminoacids (AA), complete proteins and starvation on ketosis - even though this wasn't the exact original purpose of the study.

Free Fatty Acids (a higher level indicates a "deeper" ketosis)- the highest during starvation, lower with AA and complete proteins (no significant difference between those two), and the lowest with carbs.

Ketone bodies (a higher level indicates a "deeper" ketosis) - the highest during starvation, lower with complete proteins, even lower with AA and the lowest with carbs.

Now here's where things get REALLY INTERESTING:

Insulin (a higher level indicates a "shallower" ketosis) - the highest with carbs and AA (about the same), but the lowest with complete proteins and during starvation (about the same).

Glucose (a higher level indicates a "shallower" ketosis) - the highest with carbs, a bit lower with AA (but not much), and the lowest with complete proteins and during starvation (again, about the same).

The conclusion?

Starving yourself or eating nothing but pure carbs represent the opposite ends of the ketosis spectrum (we know that already), there seems to be a significant difference between consuming proteins in a form of complete proteins or aminoacids. Proteins in their simplest form (aminoacids) seem to break up ketosis much more severely than the more complex forms of proteins.

So if you're worried that the carbs and aminoacids in your shake will throw you too far out of ketosis - then just do what the "complete protein" group of people in the study did, and eat a steak instead. :)

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protected by Eric Kaufman Apr 6 at 16:29

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