Last Updated on
The ketogenic diet is a way of eating that is very low in dietary carbohydrate.
Perhaps you are wondering about trying the diet, yet there are some burning queries in your mind.
Maybe you’re wondering about the health benefits?
Or maybe you have a few concerns over some potential side effects?
This guide will take a look at the most common questions concerning keto diets, and then provide the answers you need.
1. What is the Ketogenic Diet?
Put simply, the ketogenic diet is an eating plan that emphasizes high-fat, moderate-protein, and low-carb.
As you can see in the above food pyramid, the diet is based around animal foods, low-sugar fruit, and vegetables.
Keto restricts carbohydrates to a level that results in the body switching to burning fat for fuel.
On the positive side, the diet has a wealth of health benefits, but there are also some potential side effects to be aware of.
We’ll explore both the pros and cons later in this guide.
2. How Does the Ketogenic Diet Work?
When we are eating large amounts of carbohydrate, our body stores them as glycogen.
Glycogen is a form of stored glucose which we can find in our liver and muscles. In the presence of adequate glucose, the body will burn this carbohydrate as its primary source of energy.
However, when we restrict carbohydrate, after a few days our body becomes deprived of glycogen.
As a result, our body requires a new energy source – fat.
To burn fat for energy, our body must first convert the fatty acids in our body to compounds known as ketone bodies.
These molecules are produced by the liver in times of carbohydrate restriction, and they are otherwise known as ‘ketones.’
The term ‘ketosis’ refers to the state/process during which the body burns fat for fuel.
3. What is Ketosis?
As previously mentioned, ketosis simply refers to the state during which the body burns fat for fuel.
In other words, when the body is producing ketone bodies, we are “in ketosis.”
The three ketone bodies are shown above; acetone, acetoacetate, and 2-hydroxybutyric acid.
Overall, the general population spends very little time in this state due to the prevalence of high-carb diets. However, when carbohydrate is very low—either through lack of food or a low carb/keto diet—the body can freely enter ketosis.
While this may sound like a radical change for the body, it is a normal metabolic state. In fact, it is likely that humans spent significant amounts of time in nutritional ketosis throughout our history, especially during cold winters and the ice age.
Of course, just because we used to do something doesn’t necessarily make it right or healthy. But being in ketosis does confer some health benefits, and it is why the diet enjoys popularity.
In addition to to the popularity of keto diets for general health, ketosis sometimes plays a role in the treatment of medical conditions such as epilepsy.
4. Are There Any Signs Or Symptoms of Ketosis?
Yes, there are some common signs that the body is in ketosis.
These usually show up within the first 48 hours or so.
While some symptoms will probably be welcome, unfortunately, they are not all positive.
For example, these symptoms may include the following;
- Bad breath (a kind of metallic taste in the mouth).
- Sudden loss of weight (mainly due to losing water weight).
- Feelings of fatigue and lethargy while the body adapts to burning fat.
- Decreased performance in the gym/sports.
- Better satiety, reduced appetite and fewer food cravings.
All ‘symptoms’ related to ketosis are generally short-term only, and they soon subside (except for the improved satiety).
We will look at these more when we examine the potential side effects of starting keto.
5. How Can I Tell If I’m in Ketosis?
It isn’t necessary, but some people like to know if they are in ketosis or not.
If you wish to track this, then you can use urinalysis to have a better idea.
This urinalysis involves using something called a ‘ketone strip’.
After taking a urine sample, holding the strip in the sample will cause the ketone strip to change color.
The color it changes to will represent the amount of ketones in the urine.
Ketone strips are not a 100% foolproof method to measure your level of ketosis, but generally work well.
See here for some more information: how to use ketone strips.
6. What Happens To the Body in Ketosis?
Well, many things happen when your body switches away from burning carbohydrate to use fat for fuel.
It’s important to be aware of this, because you are changing the way in which your whole metabolism works.
Here are the main things to note;
- As our body adjusts and enters ketosis, it up-regulates fat-burning enzymes.
- Our liver begins converting fatty acids into ketones for fuel.
- Blood glucose and insulin levels typically fall due to the small amount of dietary sugar/carbohydrate.
However, remember that it may take a bit of time for the body to get used to these changes.
7. Is Ketosis Bad For You?
No, ketosis is a normal metabolic state that the body can freely enter (and leave) when carbohydrate/food intake is low.
Generally speaking, the only issue is the short-term side effects while the body adapts to this new state.
That said, there can be some complications in people with diabetes (see the next question).
Other than this, there is nothing especially bad about ketosis.
We are all different, so perhaps being in ketosis won’t be the right fit for every individual. But there is nothing inherently dangerous about it.
8. Does Keto Cause Ketoacidosis?
First things first; ketoacidosis is an incredibly dangerous medical emergency.
The condition is otherwise known as diabetic ketoacidosis (DKA), and it usually occurs as a result of the poor management of diabetes (particularly type 1).
Symptoms may include abdominal pain, dehydration, and shortness of breath. Ultimately, ketoacidosis can be fatal.
Should anyone experience these symptoms, they should seek medical advice immediately.
Okay, but does Keto Cause It?
Since ketoacidosis results from a build-up of ketones in the blood, people often assume ketogenic diets play a role.
The assumption is made that;
“If ketosis increases blood ketones, and if excessive levels of ketones lead to ketoacidosis, then ketosis must cause ketoacidosis too”.
However, ketoacidosis and ketosis are completely different.
Specifically, in metabolically healthy individuals, insulin stops our body from overproducing ketone bodies.
For diabetics, it is essential to discuss and carefully plan any change in diet.
There is a lot of great information online, but don’t solely rely on generic information from a website – get personalized guidance from your medical practitioner.
9. Is a Ketogenic Diet Safe?
Millions of people around the world are safely doing ketogenic diets.
Additionally, systematic reviews show that very low carb diets result in better long-term weight loss than low-fat diets.
Furthermore, they tend to reduce cardiovascular risk factors more than low-fat diets do.
The single-most important thing is to research the diet before starting it.
Make sure you know how it works, the potential short-term side effects, and the overall pros and cons.
Remember: there’s no one-size-fits-all diet that’s right for everyone.
10. Is a Keto Diet the Same As Zero Carb?
No, they share some elements of carbohydrate-restriction, but they are very different overall.
Firstly, ketogenic diets include a variety of animal and plant-based foods.
On the other hand, zero carb diets completely eliminate all sources of carbohydrate and specifically focus on animal proteins.
There is a growing amount of data on the benefits of keto-style diets, but as yet there is very little on zero-carb.
As always with nutrition, we should be open-minded and this does not mean such diets can’t be healthy.
At this time, ketogenic diets have a much stronger evidence base.
11. Is Keto Good For Losing Weight?
First of all, individuals starting keto usually experience significant weight loss in the first week.
The quick drop is simply because the body stores approximately 3 grams of water per gram of glycogen. Due to dietary carbohydrate-restriction, glycogen stores drop, and we also lose this water weight.
Not only does keto result in short-term weight loss, but also longer term. A wealth of studies show that very low carb ketogenic diets beat low-fat diets for weight loss at the 3, 6, and 12-month mark.
One significant point about ketogenic diets is that they tend to increase satiety, thereby naturally reducing food intake.
12. How Much Weight Can I Lose?
Overall, the key to sustainably losing weight is compliance to the diet.
It’s not a crash diet for short-term weight loss; it’s more a way of committing to a longer-term healthy lifestyle.
Make sure it’s the right choice for you and that you feel you can stick with the diet, and, providing you formulate the diet well and eat the right foods, you should see weight loss.
How Many Kilograms Can I Lose?
This is difficult to answer; everyone is different and has a different weight and amount to lose.
In fact, if you see any diet claiming the exact same level of weight loss for everyone then it’s probably worth ignoring.
For example, some people suffering from obesity have lost tens of kilograms, while other people have less to lose.
Hormones, weight, diet, lifestyle, sleep, and an assortment of other factors play a role.
13. What Foods Can I Eat?
Ketogenic diets should be based around low carb foods, with a moderate to high intake of fats and protein.
As a result, the diet usually revolves around animal foods and lower carb plant food.
These foods usually come from the following groups;
- Dairy: limit milk and prioritize high-fat dairy foods like butter, cheese, cream, and sour cream).
- Fish: All fish is excellent, but focusing on oily fish is a good idea to get omega-3. For this purpose, salmon, trout, anchovies, sardines, and herring are all healthy choices.
- Eggs: Eggs are low carb, moderately high in fat and protein, and they’re full of essential vitamins and minerals.
- Fruit: Focus on low-sugar fruits like avocado, various berries, and olives.
- Herbs and Spices: Feel free to use herbs and spices in your cooking.
- Meat: All meat and meat products like bacon, sausages, and cured meats are OK.
- Nuts and Seeds: Most nuts and seeds are suitable for keto diets, but go easy on cashew, chestnut, and pistachio nuts as they are moderately high in carbs.
- Snacks: If you want to snack, choose options such as fruit, nuts, dark chocolate, and beef jerky.
- Vegetables: There are no problems with eating as many green vegetables as you want. However, go easy with root vegetables as they have a higher carbohydrate content.
14. What Foods Should I Avoid or Restrict?
There are two types of food that keto dieters typically restrict; foods which are moderate to high in carbohydrate, and processed fats.
While highly processed vegetable oils are technically ‘ketogenic’; they are not so good for our body.
A properly-implemented keto diet should restrict the following foods;
- Whole grains
- Cakes, cookies, and pastries
- Sugar (and any foods that contain it)
- Refined grain products (such as bread, noodles, pasta. and rice)
- Vegetable oils
- Starchy vegetables
- Root vegetables (OK in very small amounts)
- High-sugar fruits (banana, mango, pineapple, etc)
15. How Much Carbs, Fat, and Protein Should I Eat?
Every individual is different, and this very much depends on what you are eating, how active you are, and personal biology.
That said, if you are trying to get into a state of ketosis, then restricting carbohydrates to an upper cap of 50g net carbs is a good idea.
Typically, ketogenic diets are high in fat and moderate in protein.
Despite this, many people do well on a higher protein intake and manage to stay in ketosis too.
Go with what feels right for you.
16. What is a Net Carb?
Net carbs are simply the carbohydrate content of food minus the amount of fiber present.
For example, taking the potatoes on the right, per 100g they contain;
- 17 g total carbohydrate
- 2.2 g fiber
As a result, they contain 14.8 g of net carbs.
If you are wondering why we would calculate net carbs, it is because (insoluble) fiber does not get digested by the body (and raise blood sugars).
However, this rule isn’t always perfect because our body can still absorb soluble fibers.
If you wish to be sure and don’t want to attempt counting fiber intake, then you could just aim for 50g of total carbohydrate.
17. Are Carbohydrates Bad For Us?
Carbohydrates are a wide-ranging class of foods that contain everything from green vegetables and berries to soda and pastries.
Are carbohydrates bad?
As a general rule, no – not in their unprocessed state.
For example, berries growing on a tree or onions pulled from the ground; they are in their natural whole-food matrix, and they contain numerous health-supportive nutrients.
On the other hand, most commercial bread is heavily refined, bleached, and stripped of their nutritional value. Additionally, products like soda and candy are full of sugar and result in blood-sugar spikes.
So, whether “carbs are bad” or not very much depends on the type of carbohydrate.
Why Restrict Carbs If They’re Not “Bad”?
The ketogenic diet is just one dietary style.
When correctly implemented, and when it emphasizes healthy food choices, it can have some impressive health benefits.
However, it is not the only way of eating. If you feel very-low-carb dieting is not right for you, then there are other options.
18. Can I Have a Cheat Day?
You can if you must.
However, if you are trying to be healthy, then it’s not advisable.
For one thing, frequent yo-yo-ing from high carbohydrate to low carbohydrate is going to make it difficult to adapt to the keto diet.
Additionally, it’s probably confusing (and not healthy) for the body.
If someone wishes to eat more carbohydrate on a regular basis, then a ketogenic diet isn’t a good match.
Something like a moderately low-carb or paleo diet (<150g carbohydrate) may be a better choice.
19. Can I Use Sweeteners?
Sweeteners are an option, and they are certainly healthier than sugar.
However, studies on artificial sweeteners are not conclusive and systematic reviews suggest they may have an adverse effect on the gut microbiota.
So-called natural sweeteners such as erythritol, monk fruit, and stevia appear to have a healthier profile.
But it is a stretch to say that any sweetener is “healthy.”
If you wish to use sweeteners, it’s unlikely to be a problem, but in my personal view it shouldn’t be an everyday thing.
20. Should I Take Supplements on a Keto Diet?
Again, this is up to you.
Personally speaking, I believe it’s better to get nutrients from food rather than a synthetic vitamin/mineral tablet.
A diet rich in a variety of nutrient-dense food is unlikely to necessitate additional vitamin or mineral supplementation.
That said, many people find it difficult to get the daily amount of certain minerals, so supplementing is an option.
On this note, taking magnesium and potassium supplements can be a big help to people first starting a ketogenic diet.
They are helpful because these electrolyte minerals can help reduce the side effects during the ‘keto flu’.
21. Does Keto Have Any Side Effects?
Yes, keto can have some side effects – specifically when people first switch to the diet.
Some of these are mentioned in question 4, but they potentially include;
- Abdominal pain and cramps
- Constant feelings of tiredness and fatigue
- Difficulty focusing and mental fog
- Bad breath
Not everybody suffers from these effects, but for those that do it’s certainly not a pleasant experience.
Fortunately, they are only short-term.
They can be explained as the difficulties the body has in adjusting from using carbs to fats for fuel.
For more information, see here: the keto flu and how to beat it.
22. Why Do I Feel Tired On Keto?
Fatigue and feeling tired are two of the most common side effects when starting a ketogenic diet.
For example, for many people switching to keto, their body has been running on an ample supply of glucose for their entire life. Suddenly restricting this glucose supply is a significant change for the body, and in the initial stages, our body seeks this glucose for energy.
While these low energy levels are not enjoyable, they are entirely understandable in this context. When our body realizes this glucose supply is not present, it up-regulates fat-burning enzymes and starts producing more ketones.
Until the body becomes efficient at using fat for energy, these feelings of tiredness linger. For the majority of people, these side effects last anywhere from 2 or 3 days to a week.
23. What is Gluconeogenesis and How Does It Work?
Gluconeogenesis (GNG) is a metabolic process through which the body converts non-carbohydrates into glucose.
Although you may have heard people mistakenly say that “carbohydrate is essential,” this isn’t strictly true.
It is actually glucose that is essential, and a natural biological process allows us to make our own.
For example, our liver can turn amino acids (protein)—among other things—into glucose.
Since glucose is a necessary fuel for our body—particularly our brain—gluconeogenesis ensures we always have enough available.
The process happens naturally when we haven’t eaten for a while; it occurs during sleep, and gluconeogenesis fuels glucose needs in the absence of carbohydrate.
24. How Does Keto Benefit Mitochondria Function?
Mitochondria exist within every cell of our body and they are essential to our overall health.
Among other benefits, they play a protective role in our cells to protect against disease.
There are multiple ways through which they do this, and they create balance in our through controlling functions such as apoptosis.
Interestingly, research is showing that ketone bodies and—by association—ketosis, may help to improve mitochondrial health and protect against dysfunction.
25. I Heard That Keto Cures Cancer?
If you heard this precise claim, then the source needs to be more responsible.
First of all, there is some interesting ongoing research into ketogenic diets and cancer.
As part of this research, some work—particularly in regard to certain types of brain tumor—could be promising.
However, to say that “keto cures cancer” is not supported by any high-level studies.
For one thing, almost every cancer is different, and each type responds to different kinds of treatment.
Could a ketogenic diet possibly play a role as an adjunct therapy for some cancers?
Sure, but evidence-wise more research is needed, and blanket claims that it “cures cancer” are going too far.
26. Can Keto Treat Epilepsy?
Yes, a wealth of research shows that ketogenic diets may play a positive role in the treatment of epilepsy.
A systematic review shows that a ketogenic diet is a “relatively safe dietary therapy” for children.
Also, various trials show that it holds a benefit for adult sufferers of the condition when compliance remains high.
Important note; if you are considering this diet for any medical condition – talk to your medical team about it.
27. Is the Keto Diet Good For Type 2 Diabetes?
Many different nutritional strategies can improve or potentially reverse type 2 diabetes.
However, it appears that very low carb ketogenic diets are more effective than low-fat diets in reducing blood-glucose and insulin levels.
Several meta-analyses and systematic reviews show this.
In fact, a recent 2017 review of 10 randomized trials found that “the greater the carbohydrate restriction, the greater glucose lowering”.
28. Can I Drink Alcohol On Keto?
There is no reason why you can’t drink alcohol on a ketogenic diet, providing it is a low-carb choice.
For instance, typical beers and sugar-sweetened beverages/cocktails are on the avoid list.
However, wine and spirits are low in carbs and they are suitable for a keto diet. Regarding wine, it is better to choose dry varieties to minimize the carb content.
There are also low-carb beers available and these include Beck’s Premier Light and Miller Lite. Generally speaking, the ‘light’ varieties of beer only contain a few grams of carbohydrate per bottle.
That being said, everyone should still exercise caution with alcohol. While a small to moderate amount might be healthy, excessive amounts of alcohol are very harmful to health.
It also goes without saying that individuals with any addiction or dependence issues should completely avoid all alcohol.
29. Can I Drink Coffee on Keto?
Yes, there should be no problem with drinking coffee.
First, two myths need putting to rest;
- Coffee will not “kick you out” of ketosis. There is no evidence of this.
- Caffeine should not have a significant impact on blood sugar levels, although it may minimally raise these readings.
However, be aware that coffee—and caffeine in general—is one of those things that affects different people in different ways.
If you feel good after coffee, then you should be able to enjoy it while on a ketogenic diet.
On the other hand, some people find it causes dehydration/digestive/anxiety issues, and these people would be better restricting it.
There are anecdotal accounts that anxiety issues with caffeine (due to the release of cortisol) may be exacerbated while on keto.
30. What Kind of Drinks Can I Have on Keto?
Many drinks are suitable.
Similar to the guidance about alcohol, you can have any drinks providing that they are low in carbohydrate.
Some of these may include;
- Coffee (black or with cream)
- Green tea
- Black tea
- Non-sweetened cocoa/hot chocolate
- Fruit/Herbal tea
- Sparkling water
- Zeo-sugar drinks
Since milk contains approximately 5g carbohydrate per 100 ml, it isn’t really suitable.
That said, if you’re having just a little bit with your tea or coffee it is probably OK.
31. Is Keto Suitable For Vegetarians or Vegans?
It is possible for vegetarians to follow a ketogenic diet.
With the exception of fish and meat, the rest of the dietary choices can remain the same.
However, it is not easy. Being a vegetarian puts a large reliance on dairy foods and eggs for protein.
Should a vegetarian wish to include other sources of protein—such as fermented soy and beans—then a standard low-carb diet might be a better choice.
It is also possible (but extremely difficult) for vegans to follow a keto plan.
In the first place, being limited to very low-carb options and avoiding animal foods makes it hard to get sufficient protein. Certainly, it is difficult to acquire all the amino acids your body needs from such a diet.
In this diet, you would need to primarily focus on soy protein, seeds, and nuts for protein.
It would also be highly advisable to track your nutrient intake to make sure you’re free of vitamin/mineral deficiencies.
Personally, I wouldn’t recommend a vegan ketogenic diet.
32. What Do CKD and TKD Mean?
CKD stands for ‘cyclical ketogenic diet‘, and TKD refers to a ‘targeted ketogenic diet‘.
Both of these are varieties of following a standard keto diet, but with some key differences.
Cyclical Ketogenic Diets
Followers of cyclical keto diets (CKD) consume a very low amount of carbohydrate, but they have intermittent periods of a moderate to high carb intake.
This could be on the same day each week.
The reason for this carb-up is usually related to sports performance, as the bulk of high-level evidence—at this time—suggests that carbohydrate is important for high-intensity exercise.
As a result, cyclical ketogenic diets are most popular with bodybuilders and athletes.
However, this does not mean that we can’t perform exercise well on standard keto diets. For one thing, early research suggests that sporting performance on keto depends on the degree of keto-adaptation.
Targeted Ketogenic Diets
The targeted ketogenic diet (TKD) is also a standard keto way of eating except for eating carbohydrate at specific times.
In the case of TKD diets, this carb consumption should happen around the time of exercise.
As a result, TKD followers tend to eat carbs before and after exercise only on the days they workout.
33. Should I Fast on Keto?
You can if you want.
Intermittent fasting has been shown to have a few health benefits—particularly for overweight people and those attempting to reverse type 2 diabetes.
These health benefits may include better weight management, and lower blood pressure and blood-glucose levels.
By its very nature, it understandably works well for fat loss—at least in the short-term.
However, although fasting may have benefit, it is not imperative.
34. How Does Keto Compare to the Paleo Diet?
Sticking to the strict definition of a paleo diet, there are some key differences between keto and paleo;
|Carbohydrates restricted to a maximum of 50g||There is no real cap on carbs, and paleo dieters often eat starchy vegetables|
|No restrictions on dairy||No dairy on paleo|
|Low-sugar fruits only||All fruits are OK|
|No grains||No grains|
|No refined sugars/carbs||No refined sugars/carbs|
|No natural sugars||Coconut sugar and honey are OK|
Overall, both diets offer benefits and drawbacks.
Providing followers emphasize whole, nutrient-dense foods, then there’s no reason why either diet can’t be healthy.
Everyone is a little different, and paleo may be the right fit for some, while keto will suit others better.
35. Is Keto Good For Athletes?
Many athletes are performing well on ketogenic diets.
However, at this time, the bulk of high-level evidence suggests that traditional carbohydrate-fueling is the better option for high-intensity sports performance.
That said, researchers believe that fully keto-adapted athletes (over several months) may be able to perform equivalent to that of carbohydrate-fueled athletes.
To substantiate this claim, further studies on athletic performance in longer-term keto-adapted athletes are needed.
Read more here: potential performance benefits of keto.
36. Where Can I Find a Keto Macro Calculator?
Macro calculators are far from necessary, but they can be a handy aid for those who like to track what they are eating.
Perhaps the best example of these calculators is located here.
You can use this tool to plan the exact amount of carbohydrate, fat, and protein you should target.
37. What Can I Eat For Breakfast?
This is an extremely common question for those new to ketogenic diets.
Firstly, you have to get out of the mindset that breakfast is cereal and toast.
Cereal companies have done an amazing marketing job here because we all ate a traditional hot cooked breakfast in the mid-20th century.
In short, breakfast can be anything you want it to be.
Some popular options include;
- Bacon and eggs
- Steak and onions
- Cheese and vegetable omelet
- A crustless quiche
- Steamed fish and veggies
- Fresh fruit, nuts, and coffee with cream
As you can see, there is a range of different breakfast options.
For further examples and a guide that explains why keto breakfasts beat sugary cereal, just see here.
38. Where Can I Find Some Keto Recipes?
There are thousands of different websites offering a variety of recipes, and they are just a Google search away.
To get you started, you can find a few recipes here.
39. Is Keto the Best Diet Out There?
No, the best diet depends on the individual.
The food we thrive on can depend on many things, including our hormones/existing health, taste preferences, cultural considerations, and beliefs.
In other words, there is no one-size-fits-all diet that is the right match for all people.
As a result, the ketogenic diet might be a great idea for some people, but not the right match for others.
It is an option, and when done the right way it can be a healthy choice.