How Long It Takes To Become Fat Adapted

There’s a big difference between entering ketosis and becoming keto adapted. The question of the diet’s success is whether you can hold out long enough to get to the real benefits of carb restriction. 

Ketosis Vs Keto Adaptation

Keto Adaptation Exercise

With the former, you will have entered a state of lowered glucose and raised ketone levels. There are a number of methods for achieving this, but the general requirement is saying goodbye to carbs for a few days. This scarcity of energy means the body has to find a new source, and so it switches over to burning up fat cells. That step alone isn’t enough for ketosis, because the liver then has to start breaking down those triglyceride cells into smaller chains that can reach past the blood brain barrier. These ketones can now supply the body for most of its energy needs, and this is where ketosis really sets in.

Completing this process doesn’t even need to take a matter of days, assuming you’re relatively active. Athletes who train in a fasted or depleted state will likely reach ketosis by burning through their glycogen stores. People who practice regular fasts will naturally be swinging in and out of ketosis throughout the week. Getting into ketosis isn’t the difficult part of a carb restricted diet.

Keto adaptation, sometimes labelled as being fat adapted, is a different beast altogether. Here the body has to reach ketosis, and stay there long enough to cause the body to optimise cellular responses to ketones. Much of this is based on the idea that ketones do much more than transport energy from point A to B. 

They are remarkably potent signalling molecules that cause a cascade of adaptive changes. Insulin sensitivity improves, as does mitochondrial biogenesis, glycogen repletion, and much more. These are all designed to make the body better attuned to surviving and even thriving in sustained spells of starvation, or calorie deficits.

Ketones are also amazing brain boosters. These extra perks are what makes a ketogenic diet a special case amongst a heavily saturated market. You don’t lose more weight necessarily, as that still hinges on a calorie deficit. So in that sense, it’s much like any diet. What it does that sets it apart, is that keto makes it easier to lose that weight. By becoming better at functioning and performing in a deficit, the length of a decent weight loss programme doesn’t look so daunting anymore.

The Problem Of Keto – The Length Of Adaptation

How Long Till Ketosis

Despite all the positives I can throw around, the process of keto adaptation remains a huge stumbling block for fresh-faced dieters. It’s difficult to pinpoint a specific window for how long it really takes, as there are a number of different adaptations taking place. The estimate is around 12 weeks, and it can easily take more. A great example of an adaptation that you can measure, would be urinary ketones, taken with ketostix. As soon as you restrict carbohydrates, you’ll get positive readings, but then it tapers off within 8-12 weeks. This is likely because it initially treats ketones as toxic, before learning how to conserve them. One reason why testing your urine might be a good gauge at the beginning, but ceases to matter after a while. It’s definitely not a way to check for keto adaptation.

The Perks Of Keto Adaptation

This list is non-exhaustive, as research is still emerging on how ketones affect the body, but here’s what you can expect to gain, eventually, as an athlete or weekend warrior.

A Bonk Proof Brain – As the brain gets better and more receptive at using ketones, it’s prevented from going through periods of hypoglycemia and energy crashes.

Better Glycogen Retention – While glycogen stores can be down 47% after the first month, that drops to 14% after three.

Body Adapts To Use More Fatty Acids Over Ketones – Essentially freeing up more ketones to provide the brain with energy.

Greater Use Of Fat At Higher Intensities – Even heavy, explosive exercises can now be powered by fat.

More Efficient Mitochondria – The energy powerhouses use up less fuel to produce energy, while also reducing waste byproducts like carbon dioxide.

Insulin And Leptin Sensitivity – The drop in both hormones allows some downtime for stressed receptors, which can then be programmed to react stronger in the future. Insulin is still crucial in energy storage, and leptin regulates a bunch of factors that make the difficult task of weight maintenance, much easier. You’ll effectively be preventing the weight rebound that always threatens to take over once the diet’s wrapped up.

There’s plenty here that makes it worth the extra time and initial effort to power through the adaptation period. You’ll become a better athlete at most intensities, and gain stable energy levels that last across the day without the usual post-meal and post-exercise dips.

Going In And Out Of Ketosis

This is where it becomes extremely important to manage the diet. Letting carbs sneak back in, not staying under the 25-50g upper limit, and playing with carb cycling, all these end up keeping you in that space of purgatory between sugar adapted and keto adapted.

The reason why this is such a tough place to be for many, is because at this stage, the body can be forced into periods of energy scarcity. Carbs will naturally be out of the picture, gluconeogenesis (protein converting to sugar) is an inefficient process that isn’t a great outcome, and ketones can be rejected by parts of the body. These issues are only going to be amplified in anyone coming off the standard western diet strategy of consuming carbs to excess.

This plays a big part in the keto flu, which is the hangover-like effect of stepping into ketosis that can last from days to a matter of weeks. Sure, some it is down depleted electrolyte levels, but even that is due to the body being a novice at handling low insulin. This goes away with keto adaptation. Flirting with carbs beforehand is only going to keep the body shuttling back and forth between fuel states, meaning a slower rate of ketone optimisation, and forcing you to go through the whole pain of keto flu all over again. 

On a brighter note, the downsides and length of fat adaptation doesn’t have to apply for you. There are going to be a few lucky populations who can go through this with less hitches. As I covered in a previous article, ketosis can be achieved through mechanisms that don’t even fully take carbs off the menu.

People Who Don’t Have To Go Through Keto Adaptation

Athletes – Exercise-Induced Ketosis 

Don’t worry if you don’t have a few medals hanging behind glass frames, the term athlete doesn’t just apply for professionals. If you’re training most days of the week, and at painful intensities, then chances are you’ve already initiated the metabolic shift from sugar to fat. Now this doesn’t make you adapted, but it does mean that the body will have some experience with burning ketones for strenuous exercise. Extra points if you’ve been training fasted, which will have already put the body in a slight ketotic state.

The caveat here is that this necessitates high intensity exercise, which in fairness cancels out most people.

Intermittent Fasting Into Ketosis – More Glycemic Control

As a huge fan, I’ve already covered the fact that fasting speeds up ketosis, over several articles. Once again, this may not be enough by itself to complete the adaptation, as it’s quite trendy to end the fasting window with a mountain of carbs. Any spike in sugar instantly suppresses the signalling effects of ketones, and has the body retracing its steps down the adaptation ladder. You then have to wait till the next spell of ketosis, which might not come until the last few hours of the next fast.

But with all that being said, shifting back and forth between the glycolytic (sugar) and lipolytic (fat) systems is far more beneficial than simply camping in carb camp. You’ll still see the body adapt itself to use ketones efficiently when there are no carbs coming in, significantly improving the transitional process. In this sense, even without opting for a low carb diet, you can gain a lot of benefits just by skipping a meal or two

Previous Low Carb Experience 

Low Glycemic Index Foods

The adaptation doesn’t simply reverse in the scenario where you retreat back to a high carb diet, the changes in metabolic flexibility will remain ready for the next time you decide to drop again. With that mind, it would be smart to taper off on sugar before making the full commitment. Simply changing to high fiber, low GI sources would be a significant step in easing off the glycemic rollercoaster that would otherwise be taking place on a daily basis. 

For instance, if your current carb sources are the traditional sort, such as rice and bread, you could make straight swaps for chickpeas and sweet potatoes, while increasing the portions of vegetables and protein on your plates. Protein plays a major role in keeping blood sugar stable, making it great for transitioning between high carb and high fat diets.

Essentially you’d be preceding a ketogenic diet with a preparation phase that lowers glycemic load on the system, conditioning the body to deal with the complete carb restriction that follows. This should be allowed to go on for at least 2 weeks, but you’d be best off running it over a couple of months, giving plenty of time to taper down. If you go through cycles of bulking and cutting, like any rational lifter, then the last stretch of weight gain could be used to make the changes. In this fashion, you don’t have to contend with both a calorie deficit and carb restriction at the same time. At least not yet.

For the best effects, you can fit the Low GI within an intermittent fasting protocol. The fasts can last for 16-18 hours, and will combine well to control blood sugar. 

The reason I’ve ended up with a modified ketogenic fasting diet, is because they complement each other perfectly. Both are essentially states of fasting, and it’s much easier to head into a long fast when the last meal didn’t end with a huge carbover. There’s no hunger rebound, no craving, leaving you free to be productive at whatever it is you’re reasonably good at.

The Takeaway – Keto Adaptation Takes At Least 12 Weeks

Becoming Fat Adapted

And it’s worth the wait. Being metabolically flexible allows you to switch better sugar and fat burning pretty much seamlessly, and in the cases of most western diets, there’s next to no opportunity to focus on fat burning. The typical eating pattern sees continuous spikes of glucose and insulin, which acts to blunt the levels of ketones and fat oxidation. So there’s good reason for practically anyone to go through the 12 weeks of keto adaptation. You could do the time, wrap up and retreat to a more moderate all-inclusive dieting style, and reap the benefits for the years to come.

If time is money and you’re getting fidgety at the thought of three months of mild to moderate discomfort, there’s plenty you can do to speed up the process. Regular exercise, intermittent fasting, and a prep phase Low GI diet can all work across the same channels as keto. When you’re dropping in all three, you’re making conscious lifestyle decisions that make up the ideal playground for a keto adapted, fat burning machine.

More Diet Guides And Tips On My Blog

Why I Chose To Combine Fasting With Keto

11 Ways Keto Boosts Your Brain

What I Learned This Week On Fasting And Keto

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