If you keep even a toe dipped in the waters of social media or the internet at large, you have most likely heard someone singing the praises of the ketogenic diet in recent times.

At first glance, it’s obvious why.

Many people report impressive fat loss when following the diet and it doesn’t take a nutrition degree to observe that the average human eats too many carbohydrates and are overweight or obese.

On the face of it, something that is based around moderate protein intake and minimal carbohydrate consumption sounds like a winner for body composition.

I have used variations of the ketogenic diet for varying amounts of time with every kind of person from those wanting to look hot to people with bad health problems. 

My intention is not to blindly support or dismiss any method because, as with many things in fitness the real answer is ‘it depends’.

The ketogenic diet is not without its downsides and is often altered and tweaked to the point it’s no longer a ketogenic diet.

As you will see, my personal opinion is that a strict, standard ketogenic diet can be useful for 4-6 weeks for rapid fat loss, improving eating habits and fast changes to important health markers.

However, it is not physiologically possible to sustain intense, anaerobic exercise on a ketogenic diet as it cannot be fuelled by fat or ketones.

Simply from a performance perspective alone, a standard ketogenic diet cannot support intense training which should be the backbone of any long-term training plan whether the objective is sports performance or just looking better.

The reality is that there is little evidence that a standard ketogenic diet out performs any other well structure diet based on natural food and calorie control when comparing FAT LOSS over months or years.

Initial WEIGHT LOSS is usually more for reasons we will explore and can create unrealistic long term expectations.

Unfortunately, many ‘experts’ have jumped on the ketogenic bandwagon and of course deliver fast results in the first few weeks, confirming the unsuspecting individual’s belief that they have finally found a solution.

There are various reasons for the initial results surge as we will see soon.

One reason is simply that people moving from a high carb, poor diet to one with more natural foods, high fats and more protein, will naturally reduce their calorie intake as their appetite is blunted and the food they eat satisfies them for longer.

We have to be careful not to attribute the effects to the wrong cause!

Also, the psychological rebound effects of the inevitable re-introduction of carbohydrates, the awkward social factors and loss of drive in the gym beyond 4-6 weeks, results in a very high rate of failure in the medium to long-term.

I see little point in engaging in something that can be quite a shock to the system if you are already planning to completely dump it and revert back to normal at the end of it.

In fairness, that could be said about any diet but from coaching experience, the nature of a standard ketogenic diet makes it much more likely.

The good news is that there are ways to manage ketosis to improve body composition AND performance, provided we have a good understanding of what’s going on.

What follows is an express journey through the realities of ketosis and key considerations on how best to use the process, if at all.

Please note I am not going to delve into the effects of ketosis on certain diseases etc, we are only looking at the benefits and drawbacks for losing body fat and keeping it off.

WHAT IS A KETOGENIC DIET?

Ketosis is a naturally occurring state in our bodies activated when blood sugar is in short supply.

Ketones are produced in the liver as an alternative energy source.

A ketogenic diet is generally accepted as one in which less than 100 grams of carbohydrates are eaten per day.

Once ketosis has been established, this can be reduced further, likely accelerating fat loss.

Protein and carbohydrates need to be limited (to varying degrees) to create a state of ketosis.

Naturally, this is a good thing as it moves us away from the high sugar and starch diets that have dominated the last 30 years.

As a matter of course, dietary fat intake must increase to make up the calories required to maintain a normal metabolic rate.

The high fat is not want induces ketosis and so in theory is not ‘essential’ to make ketosis happen.

However, simply eating protein and vegetables would lead to changes in hormones that encourage a normal metabolic rate.

Without increasing calorie intake through higher fat consumption, you would likely find yourself eating 600-800 calories per day and experiencing stalling fat loss within a few weeks (as is typical on extreme calorie restriction diets).

WHAT USUALLY HAPPENS?

Your body runs on protein, fats and carbohydrates in varying amounts with exact proportions dependent on your body type as well as the type and intensity of exercise being performed.

It’s not the purpose of this article to get into body types, but some people can lose body fat whilst eating more carbohydrates than others.

This is the first point worth noting in determining whether the potential stress and workout performance deterioration typical of a ketogenic diet is worth it or even necessary.

But back to ketogenic diets…

Carbohydrates are the body’s preferred source of energy as they are essentially easier to burn than anything else.

This is the basis for encouraging low carb diets for fat loss so that the body is forced to delve into fat stores.

It won’t do that when carbs are being eaten all the time such as eating toast for breakfast, sandwiches for lunch and pasta for dinner!

Carb stores are limited in the body and any excess is converted and stored as body fat (which unfortunately has no limit!)

Carb stores can be depleted relatively quickly, leaving the body to turn to other sources of fuel, namely free fatty acids (from dietary fats and converted from stored body fat) and ketones if certain conditions are met.

Your brain and nervous system cannot use free fatty acids for fuel and so require ketones, derived from the incomplete breakdown of free fatty acids in your liver.

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Once enough ketones have been produced and are present in your blood, various knock-on effects occur at a hormonal level including:

1) Reduced levels of the hormone insulin thus reducing ‘storage’ patterns.

2) Increased levels of the hormone glucagon thus increasing the release of free fatty acids from fat cells and greater free fatty acid metabolization in the liver.

Ketosis is essentially the result of a shift from a glucose-based metabolism to a fat-based metabolism, essential for altering your body composition.

Personally, I have had great success with coaching clients using more simple fasting based diets which also include carbohydrates.

That’s not to say a standard ketogenic diet doesn’t work, but it’s always important to consider the ease with which a diet can be implemented for long-term success.

At this point we should note a key feature of carb depletion that often causes psychological problems, particularly for those prone to repeated dieting.

Water bonds to glucose (from carbohydrates) in a 3:1 ratio in your body.

This means that when you reduce the level of glucose in your body (by not eating carbs) water is also released.

This explains why in the first few days of a low carb diet, you spend a lot of time starting at the toilet walls!

This loss of water can cause fast and impressive drops in what your bathroom scales say, with anything from 1-7kg of weight loss reported in just a few days.

Whilst this can be great for initial motivation, the drop is largely ‘fake’, misleading and unsustainable.

WEIGHT loss will slow down soon after.

This can lead to feelings of “Oh no, this isn’t working either” when the reality is that you HAVE kick-started FAT loss and can continue to at a steady, healthy rate.

There is more bad news from that perspective in that when carbs are re-introduced, WEIGHT gain can be rapid (like 1-2kg in a day) even though no FAT gain has occurred!

If you don’t understand what’s really happening it’s very easy to believe you suddenly stacked on fat again!

WHEN DOES KETOSIS KICK IN?

Fat burning can only occur in the absence of alcohol and carbohydrates which will always be used for energy first.

Excess carbs are converted and stored as body fat but alcohol cannot be stored. It’s presence simply shuts down fat burning until the liver gives the all clear!

When you eat carbs, they raise your blood sugar levels, sparking insulin production and lowering glucagon, shutting off ketone formation/preventing ketosis.

Day three of minimal carb intake is when most fuel is derived from free fatty acid breakdown and ketone production.

Ketone use by muscle tissue actually tends to cease after around 21 days when free fatty acids takeover as the primary fuel source, except in the brain where ketones are the only usable fuel after carbohydrates.

This is where we want to be to maximize fat loss.

Should ketosis not occur under conditions of low carb intake, there is likely to be an abnormality in the individual’s metabolism and medical assistance/testing should be sought.

KEY TIP #1

Whilst this isn’t specific to ketogenic diets, it is important knowledge.

The body will store and burn carbohydrates first, ‘ignoring’ any circulating fats in the bloodstream which were consumed with the carbohydrates.

Eating foods containing carbohydrates and fat at the same time is likely to lead to the storage of circulating fats if glycogen storage sites (primarily your muscles and your liver) are already full.

However you eventually choose to construct your diet, you’re best to avoid foods with carbohydrates and fats in together (e.g. cheesy pizza!)

You may also struggle for brainpower and concentration for the first 1-3 weeks.

There is little that can be done about this.

You may like to start such a process when you don’t have brain intensive period at work or study to do for exams!

Anyone operating heavy machinery should also proceed with extreme caution.

You should also note that there is never a point where the brain requires no carbs at all.

A small amount of carbs is therefore required when following a ketogenic diet so don’t blindly just eliminate all carbs and expect to function well on a daily basis!

KEY TIP #2

At first, ketosis can be achieved on 100 grams of carbohydrates per day – roughly the amount the brain needs at this point.

Once the brain has adapted after approximately 3 weeks, fewer carbs are required and under 30 grams of carbs per day is recommended.

You can of course start on under 30 grams but this may make using brain power more difficult!

50g may prevent levels of the thyroid hormone T3 from dropping, thus maintaining your metabolic rate in the long term and preventing stalled fat loss after a few weeks.

It should be noted that carbohydrates from fibre do not count towards this total.

For instance, if a food is listed as containing 15g of carbohydrates and 6 grams of fibre, only 9g count towards the daily total.

HOW MUCH PROTEIN SHOULD YOU EAT?

If you have studied nutrition to any level, particular if you are engaged in weight training, you will know that you must eat enough protein for feelings of satiety and to maintain and build lean muscle tissue.

The advice is often to just eat as much as possible.

Whilst this is great advice, particularly if you are used to a high carb diet and need to make sure you feel satisfied on your new diet, we need a little more detail when it comes to a ketogenic diet.

When you first start a ketogenic diet you will likely go through all sorts of unusual ‘feelings’ with both mental and physiological routes.

If your body is used to consuming and using carbs for fuel, you can feel very hungry as your body continues to crave sugars.

Because you have not adapted hormonally as described above, your body can also search for other sources of fuel, namely the breakdown of muscle tissue to gain access to and use the stored amino acids.

It is therefore important to consume high levels of protein to minimize muscle tissue breakdown.

KEY TIP #3

For the first three weeks of your ketogenic diet, the recommended daily protein intake is about 1.6g per 1kg of lean body weight or 150g in total (whichever is higher).

After three weeks, revert to 1.6g however much you weigh.

If you are engaging in hard training, 30-40g from this total should be consumed immediately after your workout, preferably in an easily digestable shake.

After about 21 days, free fatty acids are the main fuel and protein sparing tends to occur so less is required from the your diet.

Protein also causes insulin release when ingested, just like carbohydrates but to a lesser degree.

Excessive protein intake may therefore prevent ketosis for the reasons outlined earlier.

MISSING OUT ON OTHER THINGS ON THE KETOGENIC DIET

One of the other issues with a ketogenic diet is the lack of fibre which usually comes packaged in carbohydrates.

This can be easily overcome by eating large salads (within the 30g carbohydrate limit) and taking a fibre supplement (ensure it is sugar-free).

Similarly, taking a good multi-vitamin is recommended to make sure that you don’t miss out on anything vital to your basic health.

Next, because the ketogenic diet naturally results in increased water excretion, it can bring with it a loss of electrolytes, namely sodium, potassium, calcium and magnesium.

These should also be added to the diet particularly if you are also performing intense exercise, sweating lots and/or start to feel light-headed (this can occur due to a fall in blood pressure as sodium levels drop).

I recommend Alkalising Salts by Phil Richards Performance.

Last, but certainly not least, high water intake is required due to the diuretic nature of a ketogenic diet.

1.5-3 litres is recommended depending on body size and exercise levels.

IS THE KETOGENIC DIET MORE POWERFUL THAN OTHERS?

As discussed earlier, the reality is that most of the ‘magic’ of ketogenic diets is likely to stem from the age old recommendation that calorie intake must be lower than calorie expenditure (known as a calorie deficit).

Studies examining a ketogenic diet at maintenance calories (no deficit created) shows no weight loss other than the water loss that comes with minimal carbohydrate intake.

From that perspective, it is unlikely to be any more effective than a diet containing carbohydrates that also operates at below ‘maintenance’ calories.

A calorie deficit can be created in a variety of ways, explaining why people with a high metabolic rate or who train lots can still lose body fat.

As with any diet we must reduce calorie intake, but also ensure that we don’t drop them so low or so fast that we cause decreases in thyroid hormones (the metabolic controllers) and/or losses of lean muscle tissue.

One of the misleading nuggets of information that circulates about the ketogenic diet is that you can eat as much protein and fat as you want which sounds awesome especially if you like bacon and butter!

This may be true ‘by accident’ if eating as much as you want only takes you to a point of satiety that doesn’t break the law of thermodynamics.

In other words, if you are still burning more calories than you are consuming, you should lose body fat.

Whilst everyone is different, guidelines are as follows:

Calorie levels below 1000 calories per day (for any individual) will cause significant drops in metabolic rate.

Calorie intake should be around 22 calories per 1kg of lean body weight.

For instance, if you weigh 80kg with 30% body fat that leaves lean bodyweight of 80kg x 70% = 56Kg x 22 calories = 1232 calories per day.

To maintain metabolic rate we should aim for 1200-1300 calories per day.

Whilst more dramatic weight loss is tempting, aiming for 2lbs per week is a good target.

Smaller individuals should aim for 1-1.5lbs otherwise metabolic slowdown can occur.

WHEN TO EAT CARBS ON A STANDARD KETOGENIC DIET

There is little evidence to suggest that eating your small daily amount of carbs is more effective at any one time or spread throughout the day.

If you find it easier to have a bigger salad giving you all your carbs in one hit, that’s fine, or you can spread them across your meals.

What about taking advantage of the natural post-workout insulin rise?

I mentioned at the start that a standard ketogenic diet simply cannot work on a permanent basis for anyone wanting to exercise hard.

We will soon discuss a Cyclic Ketogenic Diet which enables you to maintain ketosis whilst recovering from intense exercise.

For now, the important point is that on a standard ketogenic diet, you won’t be able to sustain hard exercise anyway, and therefore the resultant post-training insulin rise and timing become largely irrelevant.

HOW TO DO A STANDARD KETOGENIC DIET

Let’s pull together what we know at this point.

1) Set your total calories at 22 calories per 1kg of lean body weight.

2) Set protein at 1.6g per 1kg of lean body mass

Adjust this figure upwards to 150g for the first three weeks if it is under then revert back to 1.6kg per 1kg of lean body mass after this time.

Remember 1g of protein = 4 calories.

3) Set carbohydrates at 30g per day.

Remember that 1g of carbohydates = 4 calories.

4) Set fat intake at the rest of your daily calories.

Remember that 1g of fat = 9 calories.

EXAMPLE:

1) You weigh 80kg at 30% body fat.

80kg x 30% = 24kg of body fat.

You have 80-24kg=56kg of lean body mass.

TOTAL CALORIES = 56kg x 22 calories = 1232 calories per day

2) PROTEIN = 56kg x 1.6 = 90 grams of protein

90g x 4 calories = 360 calories

3) CARBOHYDRATES = 30grams of carbs

30g x 4 calories = 120 calories

4) FAT = 1232 – 360 – 120 = 752 calories remaining

752 calories / 9 calories = 84 grams of fat

So each day you should eat 90 grams of protein, 30 grams of carbs and 84 grams of fat.

Remember that protein intake should be adjusted upwards to 150 grams for the first three weeks.

SO WHAT DO I DO IF I WANT TO PERFORM INTENSE EXERCISE?

The indisputable reality is that if you want to perform regular intense exercise to the best of your ability, you need to ingest carbohydrates.

This includes circuit training, Crossfit, 400m interval repeats, weight training and so on.

There are few things better for mental and physical health than being able to smash an intense workout and feel great about yourself after.

This can be the polar opposite experience many people have when they barely consume carbs and workouts feel more like trying to survive torture!

Without going into it too much, in the bigger picture of fat loss, many studies show that intense exercise leads to greater fat burning after and between workouts than low intensity exercise, as your body spends lots of energy bringing you back down to your normal metabolic state.

In a nutshell, when you perform this type of anaerobic exercise, it all happens too fast and at too high an intensity for your body to process oxygen and utilize free fatty acids for to fuel it like it can at low intensity, aerobic exercise.

Intense exercise can only use carbohydrates as a fuel (if we ignore creatine phosphate for very intense, short burst, sprint efforts).

This is a physiological fact.

Some athletes (particularly endurance athletes) report good results from following a ketogenic diet when at the stage of their season when training is of a lower intensity and performance isn’t so important.

The effect can be becoming more efficient at fat metabolisation which is very useful in long events as it will prolong the point at which you delve into glycogen stores which is often closely followed by the well-known phenomenon of ‘bonking’!

They then tend to transition and increase carbs as training intensity increases and more anaerobic work is done, which brings us back to the point that a standard, full time ketogenic diet won’t produce optimal results.

Anyone who says you can perform well on a standard ketogenic diet every day, forever either…

1) Hasn’t really stuck to a ketogenic diet and regularly cheats
2) Isn’t training as hard as they say they are or as hard as they could
3) Is trying to sell you some form of ketogenic diet coaching

Anything else goes against the laws of basic human physiology.

The good news is there are two main ways to get the fat loss benefits of a ketogenic diet but avoid the performance and long-term progress tripwires of a standard ketogenic diet.

1) Consume carbohydrates around intense exercise (Targeted Ketogenic Diet)

After intense exercise, insulin naturally increases to push blood glucose into muscles for refueling.

This will only last a short time before insulin decreases again and a state of ketosis is achieved once more.

The loss of ‘fat burning time’ is neglible and the improved workout performance will more than make up for it.

Consuming 25-50g of any carbs, 30 minutes before training will increase glycogen synthesis after training whilst maintaining ketosis the rest of the time.

Consuming another 25-50g immediately after training in the form of glucose will aid further post-workout recovery.

Fructose and sucrose should be avoided as they may refill liver glycogen and interrupt ketone formation.

Avoid fat consumption in this post-workout recovery meal/shake.

2) Use a weekly 12-24 hour ‘refeed’ (Cyclic Ketogenic Diet)

A carbohydrate ‘refeed’ can be used successfully every 3-12 days.

For simplicity and to fit typical social weeks, either of the following is best as a general guideline for a seven day period.

Option A: 5 day ketogenic diet with 2 day re-feed
Option B: 6 day ketogenic diet with 1 day re-feed

Generally, muscle glycogen can be refilled in 24 hours hence the birth of ‘carb days’!

The great news is that these carbs are best coming from high GI foods especially in the first 24 hours so you can still enjoy some of the ‘naughtier’ foods.

If you continue over 24 hours then switching to low GI foods for the remainder of the refeed will likely bring better results.

Assuming hard training and full depletion of your muscles, you should aim for 10 grams of carbs per 1kg of lean body mass in the 24 hour period.

If we use our 80kg @ 30% body fat example from earlier…

80kg x 70% = 56kg of lean body mass

56kg x 10g = 560g of carbs

KEY TIP #4

Start your carb up 5 hours before your final workout as this allows for liver enzymes to return to normal ready for metabolizing carbohydrates.

HOW TO DO A CYCLIC KETOGENIC DIET

Let’s pull together what we know at this point.

LOW CARB PERIOD OF 6 DAYS:

1) Set your total calories at 22 calories per 1kg of lean body weight.

2) Set protein at 1.6g per 1kg of lean body mass

Adjust this figure upwards to 150g for the first three weeks if it is under then revert back to 1.6kg per 1kg of lean body mass after this time.

Remember 1g of protein = 4 calories.

3) Set carbohydrates at 30g per day

Remember that 1g of carbohydates = 4 calories.

4) Set fat intake at the rest of your daily calories

Remember that 1g of fat = 9 calories.

EXAMPLE:

1) You weigh 80kg at 30% body fat.

80kg x 30% = 24kg of body fat.

You have 80-24kg=56kg of lean body mass.

TOTAL CALORIES = 56kg x 22 calories = 1232 calories per day

2) PROTEIN = 56kg x 1.6 = 90 grams of protein

90g x 4 calories = 360 calories

3) CARBOHYDRATES = 30grams of carbs

30g x 4 calories = 120 calories

4) FAT = 1232 – 360 – 120 = 752 calories remaining

752 calories / 9 calories = 84 grams of fats

So each day you should eat 90 grams of protein, 30 grams of carbs and 84 grams of fat.

Remember that protein intake should be adjusted upwards to 150 grams for the first three weeks.

HIGH CARB REFEED:

5 hours before final workout before re-feed: 25-50 grams of carbs

2 hours before final workout before re-feed: 25-50 grams of carbs

24 hour refeed:

10g of carbs per 1kg of lean body mass
2g of protein per 1kg of lean body mass
1g of fat per 1kg of lean body mass

CARBOHYDRATES: 56kg x 10g = 560g

PROTEIN: 56kg x 2g = 112g

FAT: 56kg x 1g = 56g

Alternatively, you can simply have a free day when you eat what you want.

This can work and release the mental burden of counting stuff but if fat loss slows it might be because you’re going too far with your carbs and fat!

WHICH VERSION OF THE KETOGENIC DIET WORKS BEST?

The diet that will work best is the one you can stick to longest and which doesn’t…

…cause any lasting metabolic damage/slow down
…ruin your social life (notwithstanding necessary periods of committing to your fat loss goals)
…works best for you!

There are various health-based reasons not to do a ketogenic diet, therefore if you have any existing medical issues, you MUST consult your GP first before starting a ketogenic diet.

Whilst any improvement to your diet can help improve markers of health, you should still speak to your GP first.

STILL WANT TO DO A KETOGENIC DIET?

This article briefly covers a lot of misunderstandings from uninformed ketogenic ‘spin offs’ which don’t really achieve ketosis to the level required because they simply focus on ‘eat lots of protein and fats and don’t eat carbs’.

Also, many diets labeled as ‘ketogenic’ are really just low carb and you now know the conditions and parameters required to really make it happen.

Others simply restrict carbs so much that eventually they are unsustainable for virtually everyone and unreported ‘treats’ creep in.

It is therefore no better than a simple, calorie controlled diet where carbs are ‘allowed’ but at the right times.

The reality is that people have been in great shape and lost body fat whilst eating carbs for many, many years and they will continue to do so.

There is no magic about a ketogenic diet it simply gives you a reliable structure to work from.

I do not recommend trying to follow a standard ketogenic diet as a day-to-day lifestyle to maintain for months on end.

You will either cheat or become miserable and your exercise time will likely be a horrible time.

In my opinion from research, personal experience and those of my clients, eating carbohydrates around intense exercise or having a refeed day are the best options for a more enjoyable, flexible lifestyle that still allows for great results.

You can stay lean, improve your health and still enjoy eating out with friends and family.

A little discipline and planning goes a long way and you’ll soon be in a routine that gets the results you want!

Finally, to really make a ketogenic diet work, you should follow the instructions given in this article.

That requires counting calories and knowing your macronutrients.

There are also slight tweaks and differences in how best to apply it depending who you speak to which can make it very complicated, so don’t be surprised if you hear differing opinions.

I’ve always tried to make things very effective, but also as straight forward as possible to implement for Average Joe!

For many people this can be inconvenient and soon lead to quitting altogether.

I’ve been coaching people for ten years with hundreds and hundreds of people getting amazing results without tracking macronutrients beyond getting enough protein and using sensible portions of carbs after exercise.

It is for you to decide what works best with your lifestyle, what changes you are willing to make and what level of commitment you want to give.

Provided you are training hard 3-4 times per week, eating natural, nutritious food 90-95% of the time and sleeping well, you can transform your physique without the pitfalls and tripwires of strict dieting, ketogenic or otherwise.

If you’re a nutrition geek, I highly recommend reading Lyle McDonald’s book The Ketogenic Diet which forms the basis for this article.

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