Did you hear that exogenous ketones prevent fat loss on a ketogenic diet?
Because there have been several rumors floating around online that taking exogenous ketones will stop your body from making its own ketones so you’ll never get to burn your own stored fat.
Yet the majority of keto dieters use an exogenous ketone supplement daily because they say it helps with healthy weight loss, increases their energy levels, and helps them achieve jaw-dropping body composition results.
Who should you believe?
Could exogenous ketones be the reason you’re not racking up fat loss victories on keto?
Before we get to the answer of whether adding exogenous ketones to your diet is a good idea, you need to understand the role they play in ketosis.
Keto, ketosis, and ketones are all buzzwords you’re likely to hear in ketogenic diet chats and forums, yet many newbies are still unsure of what each one means.
While the first four letters of these words are all the same, they each have different purposes when it comes to reaching your body goals.
Keto is short for the ketogenic diet, which is centered around lowering carbs, eating moderate to high amounts of protein, and fueling your body with healthy fats to achieve ketosis.
Ketosis is a metabolic state where your body switches its primary fuel source to fat instead of glucose and produces ketone bodies, which fuel your brain. This means when you’re truly in a state of nutritional ketosis, your body burns more fat and starts producing more ketones.
Ketones are energy molecules your body uses similarly to glucose for fuel — only better. While the glucose roller coaster causes energy fluctuations throughout the day, ketones provide your body and brain with sustained energy and zero crashes.
Your body naturally creates three different types of ketones:
These are known as endogenous ketones because they’re produced inside (endo-) your body.
Exogenous ketones are man-made ketones that you take in powder or capsule form, but they work the same way and have the same effect as endogenous ketones.
So now you’re probably wondering why you would need to supplement with exogenous ketones if your body already makes them.
When you’re in ketosis, your body has officially switched gears and uses your stored fat along with dietary fat and the ketones it produces for energy.
But it can take a few days or weeks for your body to reach this point.
And it also requires starving your body of carbs, which could make life a bit unpleasant depending on how high your carb intake was pre-keto diet.
Here’s the good news: you can add exogenous ketones to your diet during this transition time to help your body figure out what to do because:
#1: They Help You Avoid Keto Flu for a Smoother Transition
As your body switches from using glucose to ketones, you can make the whole process smoother by supplementing with exogenous ketones.
As we talked about in this guide on the keto flu, adding exogenous ketones to your transition provides your body with the substrate it needs (i.e., ketones) to transition to ketosis faster.
In many cases, exogenous ketones can prevent or even eliminate the side-effects common with this phase of keto.
But that’s not the only time they work well for people on keto.
#2: Exogenous Ketones Give You Sustained Energy
Everyone’s had the experience of brain fog, mood swings, and fatigue from eating too many carbs. Excessive carbohydrate intake causes insulin resistance, inflammation, and energy crashes.
Since ketone molecules are fat-based rather than built on glucose, you’ll have a sustained source of fuel sans carbs to kickstart your day or keep you going longer between meals.
#3: They Help You Reach Ketosis Faster
Exogenous ketones are also helpful for getting back into ketosis.
During your keto journey, you may find certain foods, drinks, or protein bars may actually kick you out of ketosis unintentionally — even apparently “low-carb” snacks.
And sometimes a low-carb, high-fat diet like keto takes a bit of trial-and-error and getting used to before you stop having occasional cheat meals.
Instead of undoing all your hard work and calling it quits after a carb binge, you can turn to your trusty exogenous ketones to help you get back on track quickly.
Rather than experiencing a tough transition back and forth, exogenous ketones give you a bit more flexibility in your diet (but not a reason to cheat).
Compared to the hundreds of people who appreciate exogenous ketones for these reasons, you may come across a few misinformed folks who believe exogenous ketones and MCT oil prevent you from losing fat on keto.
So let’s unpack this next.
Some people mistakenly think taking exogenous ketones stops fat loss is based on simple, yet flawed, logic:
If you give your body exogenous ketones or something similar like MCT oil, you force your body to use that source of fuel instead of tapping into your own stored body fat for energy.
Further, some people claim your body will stop making its own ketones because it already has a steady supply of them coming in via exogenous ketone supplementation.
But all of that is entirely inaccurate.
Your body doesn’t wait until everything you’ve eaten is digested before it decides to burn fat.
If this were true, your blood sugar levels would need to plummet so low you’d be knocking on death’s door before you lost a single pound, which we know isn’t the case.
You literally wouldn’t have enough calories to run important tasks such as breathing, pumping your heart, or sending signals to your brain.
Why Exogenous Ketones Don’t Stall Fat Loss
Your glycogen stores don’t need to be completely empty for your body to start burning fat. However, your insulin levels do need to be low and you need to avoid overeating to allow your metabolism to access fat stores.
That’s why your focus should be on maintaining low blood sugar levels and periodically going without food (like using intermittent fasting, or fasting overnight for example).
Since your body requires a large amount of energy to function correctly, exogenous ketones give it a chance to work through some glucose stores while also giving you sustained energy.
So now you see the solution to losing weight isn’t avoiding exogenous ketones, but knowing when best to use them.
But first, here are a few research-backed uses for exogenous ketones and why you might want to add them to your health regimen.
Exogenous ketones are still fairly new to the science scene, so to speak.
While protein powders have been around for decades and there’s plenty of research to review, exogenous ketones aren’t quite as well-studied yet.
But since more Americans are learning the benefits of low-carbohydrate diets like keto, it won’t be long until more research comes out.
Until then, here’s what the science supports as of publishing this guide:
#1: They Can Increase Ketone Levels
Researchers in a 2018 study wanted to see if exogenous ketones could help people reach nutritional ketosis faster and alleviate symptoms of the keto flu.
What they found is exogenous ketone bodies were a “safe and effective way to increase ketone body concentrations.”[*]
And higher ketone concentrations mean your body may be further into ketosis, which means you may notice side-effects during your initial keto transition too.
While exogenous ketones can boost your ketone production, they also help tackle this next issue.
#2: May Reduce Oxidative Stress and Improve Neuronal Function
Another body of research shows exogenous ketone supplements like beta-hydroxybutyrate, or BHB, work well for replacing glucose as an energy source in your body and brain[*].
This has led some researchers to conclude that exogenous ketones may extend lifespan similarly to caloric restriction[*].
#3: They Can Improve Blood Sugar
Researchers in a 2017 study discovered exogenous ketone supplements, both ketone esters and ketone salts (which you can learn more about here), increased the level of circulating ketones in study participants’ blood[*].
And that wasn’t all they found.
Their results suggested that exogenous ketones can help lower blood sugar levels without the side effect of interfering with insulin secretion.
This is excellent news for people using a ketogenic diet to lower high blood sugar levels, such as those with type 2 diabetes.
Furthermore, the ketone drinks used during the trials helped people achieve nutritional ketosis without the use of a restrictive diet.
But having higher blood ketone levels isn’t the only goal here; it’s what happens as a result of this.
#4: May Reduce Cravings and Food Intake
Scientists from another study published in 2018 in the journal Obesity explored how ketone ester drinks, or exogenous ketones, affected people’s appetites and hunger levels[*].
What they found is that, after an hour of consuming exogenous ketones, study participants’ blood ketone levels went from about 0.2 to 3.3 mM
Along with this increase came lower levels of ghrelin, a hunger hormone that stimulates appetite.
Because of this change, participants reported feeling satisfied instead of hungry 1.5 hours after consuming exogenous ketones compared to those in the dextrose-based drink group.
Another big finding here is that glucagon-like peptide (GLP-1) and peptide tyrosine (PYY) both remained significantly lower for 2-4 hours after the exogenous ketone consumption.
GLP-1 is a peptide hormone that stimulates insulin secretion. PYY is a peptide hormone that binds to receptors in your brain to send the signal that you’re full after eating.
So, exogenous ketones could potentially help people lose weight because they reduce hunger and food intake, showing this goes beyond just an increase in blood ketone levels.
#5: Fat Oxidation is Not Diminished in Athletes
When researchers in a 2017 study tested whether exogenous ketones affected fat oxidation in male cyclists, they learned that as long as participants were completing a steady-state exercise, fat-burning was greater in the ketone group compared to the control group[*].
However, this was not the case with high-intensity exercises.
The scientists realized exogenous ketones could actually impair an athlete’s performance because they aren’t made for quick bursts of energy.
Yes, exogenous ketones are metabolized quickly and are used right away, but they’re not going to quickly replenish glycogen stores, which is what someone in high-intensity training needs.
Exogenous ketones are better for long-lasting energy so you can power through steady-state sessions.
This is why it’s important to understand what exogenous ketones can and cannot help you accomplish.
If you’re worried taking exogenous ketones may stop your fat loss efforts, your focus should be on understanding when to take them.
But first, you should know ketone supplements like exogenous ketones will not immediately trigger weight loss.
It’s not a switch you can just turn on like that.
Rather, as with all supplements, they should be used in conjunction with a clean ketogenic diet.
So if you’re trying to practice a “dirty” or “lazy” style of the keto diet and you’re hoping ketone supplements will be your free pass to easy ketosis street, you’re going to be in for an unfortunate surprise.
Exogenous ketones don’t cause weight loss, but they can help kick you into ketosis, which enhances weight loss.
As we talked about in this guide, using ketones or even making more of them on your own doesn’t mean you’re going to drop weight or decrease your body fat percentage overnight.
Exogenous ketones offer a boost to your protocol, helping to get the wheels rolling faster and smoother as long as you’re already on the right track.
So if you’re making the transition to keto, exogenous ketones can help facilitate this.
They can also help get you back into ketosis if you’ve had a larger-than-normal carb-heavy meal.
Exogenous ketones are even helpful for increasing energy levels when you’re weaning yourself off carbs.
All these perks help you feel better faster on keto, meaning you can stick with it long enough to reap the long-term health benefits.
The Best Times to Take Exogenous Ketones
To make your life easier, follow this schedule of best times to use exogenous ketones:
- Before or after a workout to enhance performance and recovery
- When you wake up in the AM for a convenient source of brain fuel
- After carb-laden meals to reduce the adverse effects of high glucose and insulin spikes
- To suppress your hunger during an extended fast or on an empty stomach between meals
- To enhance ketone production during your keto transition
It’s also smart to regularly test your blood ketone levels when using exogenous ketones to see how they affect you individually.
Ideally, you should move beyond basic urine test strips to do this and instead use a blood sugar meter to accurately assess your ketone production.
As we talked about in this podcast episode, the goal is not just having high levels of ketones.
It’s about finding the sweet spot that works for your body; the point where you’re in ketosis and it feels good for you, like a “keto high” (which is similar to a runner’s high).
You’ll never know where your sweet spot is if you’re not effectively tracking how exogenous ketones affect you.
While it may take a bit more effort, the rewards will be worth it as you make the switch from glucose to burning ketones.
Myth Busted: Exogenous Ketones Will Not Prevent You From Losing Fat (Just the Opposite)
Now that you know the science behind what really happens when you take exogenous ketones, it’s time to put this old myth to rest.
As you saw in this guide, exogenous ketones pack a number of different health benefits and can be a successful tool for reaching ketosis faster.
When you add them to a clean ketogenic diet and use them strategically, they won’t prevent you from losing weight and tapping into your fat stores.
They’ll actually help you speed up the process.
You can take exogenous ketones in one of five delicious powders or as a convenient capsule. Let us know what you think in the comments below!