Does Whey Protein Kick You Out of Ketosis? (5 Factors to Consider)

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If you’re on a keto diet, you’re likely curious to find out, “Can Whey Protein Disrupt Your Ketosis?”

I’m sure you know that you have to be wary of what you eat on keto.

And unfortunately, one wrong turn and you stop producing ketones.

However, if you’re restricting carbs and eating moderate amounts of protein, but still looking to build muscle, whey protein can be a bit of a minefield.

So, allow me to explain the ins-and-outs of whey protein and ketosis.

Does Whey Protein Kick You Out of Ketosis?

Whey protein will kick you out of ketosis. This is due to a temporary insulin spike, which will peak at around 15 minutes after you’ve consumed your protein shake. However, your ketone levels will typically return to normal after approximately 30 minutes. You can somewhat control the spike in insulin by consuming fats with your whey. You can switch to casein protein. This provides a slower release of amino acids than whey, so your insulin levels won’t be affected as much.

1. Should You Be Wary of the Insulin Spike?

A Muscular Man Drinking a Protein Shake

Yes, whey protein will kick you out of ketosis, but this isn’t as bad as it first seems.

This occurs because consuming whey protein causes an almost instantaneous spike in insulin levels.

This insulin spike will typically reach its peak approximately 15 minutes after consumption.

This also goes to show how fast acting whey protein is.

The main role of insulin in the body is to help sugar enter your cells.

And it is this sugar that the body generally uses for energy.

However, your body is unable to use sugar for energy if there isn’t enough insulin.

So, lower insulin levels will prompt the use of fat for energy.

This in turn produces ketones.

Therefore, a spike in insulin levels typically means that ketosis will be inhibited.

With that being said, the spike in insulin levels caused by whey protein will only be temporary.

In fact, once the insulin spike has reached its peak at the 15-minute mark it will then begin to taper off.

So, by around 30 minutes after whey protein ingestion your ketone levels will generally go back to normal.

Okay, admittedly you’d rather not have any of this occur.

And there are ways in which you can still enjoy a post-workout protein shake and not worry about increasing insulin.

2. Concentrate is Better Than Isolate

Whey protein can be a bit of a double-edged sword when it comes to the keto diet.

You usually have a choice of whey protein concentrate or whey protein isolate to choose from.

With that being said, and just to confuse matters slightly, there are also blended whey protein products.

Whey protein concentrate is typically around 70-80% protein per scoop.

It also contains lactose and fat to enhance the flavour.

Now, lactose is basically milk sugar and will therefore impact on your blood sugar glucose levels in exactly the same way as regular sugar.

So, at first glance you would think that concentrate should be avoided.

But let’s take a quick look at isolate before we come to a conclusion.

Isolate is approximately 90% protein, and sometimes even higher.

However, it contains less fat and lactose, plus many of the beneficial nutrients that we associate with whey protein have been removed.

You would think that the lower lactose content of isolate would make it a better choice, but this isn’t the case.

Due to the slightly higher fat content of concentrate it is the better of the whey proteins when on keto.

Remember that many versions of the keto diet require around 65% fats and 30% protein.

So, the more fats the better.

Concentrate vs. Isolate

3. Try Adding Fats to Your Whey

The main issue with whey protein is clearly the insulin spike it provides after ingestion.

And unfortunately some individuals will experience an exaggerated insulin response.

This all comes down to how quickly whey protein is absorbed by the body.

However, the main reason for this is that you typically consume whey protein in isolation without any fat,

So, in effect, by adding fat to your protein shake you can actually change the outcome.

This will generally mean that you can consume whey protein, still absorb the essential amino acids, but not experience the spike in insulin levels.


I will say that this will typically involve you having to make your shake with the use of a blender.

So, you may need to wait a while after your workout to get the nutrition you need (however long it takes you to get home from the gym).

The easiest whey (sorry, pun intended) to get that hit of fat with your shake would be a couple of good scoops of heavy cream and some form of avocado.

You could choose to add half an avocado or simply some avocado oil.

Whatever you decide, this addition of fat to your protein shake will help to keep you in ketosis.

4. Casein is Better Than Whey

Something else to consider is simply changing your protein shake.

There are of course many varieties, but the main two we are used to are whey protein and casein protein.

If you’re on keto then casein will definitely be the better choice of protein powder.

Casein provides a much slower release of amino acids than whey.

So, whereas whey protein will typically have done its job within 30-60 minutes, casein protein will take 3-4 hours.

Plus, depending on how much casein you’re taking, it may have absolutely no effect on glucose or insulin responses in the body.

With that being said, both whey and casein are milk proteins.

You can actually take things one step further and use a non-milk protein powder.

Egg proteins are considered keto-friendly and are extremely low-carb

Then again, a collagen protein powder will contain absolutely no carbohydrates at all.

However, collagen will provide less protein than either whey, casein, or egg protein powders.

So, in reality, it’s about finding what best suits you.

What’s the Difference Between Whey Protein & Casein Protein?

5. Can You Have Too Much Protein?

There is much debate about whether consuming too much protein can kick you out of ketosis.

In truth, there hasn’t been enough research into this subject to draw a conclusion.

The main issue here is that if you consume too much protein the body will turn this into glucose.

So, in effect, your body reverts to using glucose for energy rather than fat.

This is known as gluconeogenesis.

However, there has been research which proves that gluconeogenesis still occurs even while in ketosis.

So, even if you are eating a high amount of protein your body is still able to limit the use of glucose for energy, as opposed to fat.

With that being said, the research into the entire subject of gluconeogenesis and ketosis is somewhat limited.

Therefore, as a keto follower it’s always best to try to limit protein intake to approximately 30% of your daily macros.

Final Thoughts

So, as you can see whey protein does kick you out of ketosis.

However, this isn’t as bad as it initially sounds.

This is typically caused by the insulin spike from whey, which will reach its peak after 15 minutes.

But your ketone levels will return to normal after around 30 minutes.

You can limit the impact of an insulin spike by adding fats to your protein shake, or even changing your protein powder completely.

Casein will typically be better than whey protein, and the non-milk proteins are the best choice when on keto.

Finally, you don’t specially have to worry about high protein consumption, as the body will still use fat for energy.

Next, you can also read what I had to say about protein powder tasting so sweet.

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