Beginners guide to the keto diet

This on-trend way to eat has soared in popularity in recent years with its reputation of helping people to lose weight thanks to its high-fat and low-carb methods.

For more information, check out our guide to the keto diet for beginners below.

In this article, you’ll learn about

• What the keto diet is and if it’s safe
• Keto diet rules
• The top keto diet benefits
• What a weekly ketosis diet plan looks like
• Safe keto diet foods, including vegetables, fruit, snacks and drinks
• Keto diet foods to avoid
• If you need to take ketosis supplements
• Potential side effects of the keto diet
• If the keto diet is suitable for everyone
• The different types of keto diet
• Doing a vegetarian or vegan keto diet
• Exercising while doing keto

What is the keto diet?

The ketogenic diet, or keto diet for short, is a high-fat and low-carb plan that aims to turn your body into a metabolic state called ketosis.

It’s quite similar to the famous Atkins diet and other low-carb diets that have gained popularity in the last few decades. Ketosis is where your body burns fat, rather than carbohydrates for fuel.

The body usually opts to burn glucose, a sugar found in carbohydrates, for fuel, but if there’s no carbohydrates, the body’s next option is fat.

Ketosis also allows fat to be transformed into ketones in the liver to supply energy to your brain.¹

Changing to a keto diet, means the fat that you consume, or that is stored, is burnt. This is why the keto diet has become a favourite with those looking to lose excess pounds.

It’s worth noting that the body takes a few days to switch from choosing to burn glucose, to fat, so results aren’t instant.

Is the keto diet healthy?

Ketosis is natural – the human body is built to do it, but is it really good for you?

Your body enters the metabolic state of ketosis when it is predominantly using fat as fuel for your body and brain – causing a high concentration of ketosis in the blood.

The cells in our bodies usually prefer to use glucose (blood sugar) as fuel as it is usually much easier to access.

However, when you limit your carb intake, your body has no choice but to dig into its fat stores and use that as energy instead.

This also happens naturally to some extent during infancy, pregnancy, fasting and starvation.^2,3,4

It’s only in recent years that some have us have started ‘forcing’ ketosis to happen. Following a keto diet to remain in the state of ketosis has its benefits and risks.

Like with any diet, it will suit some people and won't suit others, but the actual state of ketosis is completely natural and people have been ‘doing it’ for centuries.

Keto diet rules

If you’re interested in trying out the keto diet yourself, there are a few things to be aware of first. Here are some of the basic keto diet rules you should know before you start:

1. Be prepared to say goodbye to carbs

Arguably the most important element of the keto diet is the huge reduction in your carb intake.

So if you’re used to munching on bread, pasta and potatoes everyday – this may come as a bit of a shock!

2. Get stocked up on the right kinds of fats

Since your body won’t be getting any carbs, it will have to rely on fats for energy.

This makes eating the right kinds of fats even more important.

The healthiest types of fats are monosaturated and polyunsaturated fats, which come from foods like olive oil, avocados, peanut butter, nuts and seeds, tofu and sunflower oil.

3. Be generous with non-starchy vegetables

While starchy vegetables may be off limits, thankfully you can fill your plate up with non-starchy versions to ensure you’re getting plenty of nutrients in your meals.

Find out the best kinds of vegetables to eat on a keto diet later in the article.

4. Make sure to eat fermented foods

When limiting your carb intake as much as you do on the keto diet, it’s likely that your fibre intake will be reduced too – which could leave you feeling backed up and sluggish on the digestion fruit.

So a keto friendly way to combat this is to introduce fermented vegetables like sauerkraut or kimchi into your diet plan as they’re rich in probiotic bacteria to help your gut microbiome and digestive system.⁵

5. Avoid foods with added sugar

Try to avoid foods with sugar as a listed ingredient as this could up your carb intake without you even realising it.

6. Part ways with fruit juice

Whether apple, orange or even grape, the sugar contents of fruit juice are so high that the amount of carbohydrates in them are high too – so it’s best to avoid them altogether.  

7. Up your salt intake

As your kidneys may excrete more sodium during ketosis, this could lead to symptoms of keto flu.

So to avoid this, be sure to get some high quality sodium into your meals to keep your electrolytes in check.

8. Stay hydrated

The keto diet has a diuretic effect, meaning your body can lose a lot of water⁶, so it’s key to make sure you’re drinking enough water every day to combat this.

9. Make sure you’re getting enough protein

Since your body won’t be getting energy from glucose, the role of protein in the keto diet is key for ensuring that it doesn’t use your muscles as a form of energy instead, which can lead to a big reduction in muscle mass.⁷

10 keto diet benefits

Keto can be pretty intense – especially if bread, pasta and other grains were your favourite things to eat!

Considering the gravity of that sacrifice, the health benefits should be pretty good, right? See for yourselves. Here are some of the best ketogenic diet benefits:

Keto diet weight loss

Eating lots of fat to lose fat is understandably quite a difficult concept to get your head around.

For decades we have been fed the rhetoric that low-fat = good and high-fat = bad, so when keto came on the scene in a big way, so did the confusion.

There is some supporting evidence that a ketogenic diet is an effective approach to weight loss.

• One study found that people lost 2.2 x more weight than other participants on a low-fat, calorie-restricted diet.⁸
• Another study found that people following a keto diet lost 3 x more weight than one recommended by the organisation Diabetes UK.⁹

Here are some reasons why the keto diet is so successful for many wanting to lose weight...

1. Appetite control and less cravings

Fats and proteins tend to take longer than carbs to digest– especially simple carbs like sugar, white bread, normal pasta, etc.

The keto diet is full of healthy fats and protein with very little carbs, which can help control your appetite and cravings and help you to feel fuller for longer – win!¹⁰

2. No calorie counting or tracking

Although the ketogenic diet plan may seem difficult to follow at first, once you’ve got your head around which foods to eat and which to limit in order to keep your body in ketosis, you’ve already done the hard part.

There’s no real need to count calories or track your food intake, you just stick to the plan and the weight loss should follow.¹¹

3. Gluconeogenesis

The process of converting fats and proteins into carbs for your body to use as fuel may help to burn more calories.¹²

4. Food elimination

Most people following a keto diet for the first time will have to pretty much throw their normal diet on its head.

The elimination of certain food groups will mean your typical cakes, biscuits and crisps are often off the menu, so this may help you reduce your overall calorie intake, which is essential for fat loss.

5. Increased fat burning

Following a keto diet alters your metabolism and has been shown to increase the amount of fat your burn all throughout the day – whether you’re sweating it out exercising or lazing around on the sofa – can’t complain at that, can you?!¹³

Can you lose belly fat on keto?

According to research, the lower insulin levels on the keto diet makes it easier for the body to burn stored fat.

Also, the lack of sugars and carbs on keto means your body is forced to burn fat for fuel, during exercise and when resting.¹⁴

Other health benefits of keto

There are more benefits of the keto diet than weight loss...

6. Increased ‘good’ cholesterol levels

Very low carb diets like keto are said to increase both HDL cholesterol levels¹⁵, which help the body to remove excess cholesterol from the blood vessels, protect the artery walls against bad cholesterol and protects cells and chemicals in the blood from being broken down.¹⁶

7. Maintain normal blood pressure

A recent study highlighted how a ketogenic diet can induce long term improvements in diastolic blood pressure.¹⁷

8. May reduce symptoms of Alzheimer’s

Various studies indicate that a keto diet could help to reduce the symptoms of Alzheimer’s disease and potentially slow its progression.^18,19,20

9. May improve PCOS symptoms

PCOS, or polycystic ovary syndrome, is a hormonal disorder that affects how the ovaries work.

A pilot study done in 2005 that examined five women over 24 weeks showed signs of improved markers of PCOS after being on the keto diet, which included:

• Weight loss
• Hormone balance
• Ratios LH and FSH
• Levels of fasting insulin²¹

10. May reduce acne

Some evidence suggests that following a ketogenic diet and vastly reducing carb intake could reduce acne for some people, according to a 2012 study.²²

Ketosis diet plan

A keto diet is made up of around 75% fats, 20% protein and 5% carbs.

To kickstart ketosis, 20g, and no more than 50g, of carbs should be eaten per day.

Minimise potatoes, pasta, bread and rice. Carbohydrates are also in alcohol, sweets and fizzy drinks in the form of glucose and sugars.

Fruits, especially the sweeter ones, contain carbs; a small banana has around 20g of carbs.

If you’re thinking of trying the keto diet, but unsure of what a typical day’s meals could look like, here’s some ketogenic diet meal plan inspiration to get you started, with options to add meat if you aren’t a veggie.

9 foods safe for keto diet 

When you first start out, knowing what foods you can and can’t eat can be a minefield. But don’t worry. We’ve listed some foods that are definitely safe for the keto diet, below.

1. Meat

Steak, red meat, sausage, ham, chicken, turkey and bacon are all safe to have on a keto diet plan.

2. Fatty fish

Trout, salmon, tuna and mackerel are also on the green list.

3. Butter and cream

Grass-fed varieties are best, if possible – otherwise just stick to the regular stuff.

4. Eggs

Eggs are also good to include in your plan, but look for omega-3 eggs if you can for added nutrients.

5. Cheese

Choose unprocessed cheeses like goat, cream, cheddar, mozzarella and blue where possible.

6. Nuts and seeds

Walnuts, almonds, pumpkin seeds, flax seeds, chia seeds are all wonderful additions to the keto diet, packed full of nutrients to keep you fuelled throughout the day.

7. Avocados

Thankfully both whole avocadoes or home-made guacamole are safe to eat on the keto diet.

8. Healthy oils

Coconut oil, extra virgin olive oil and avocado oil are the best kinds of oils to use on this diet.

9. Low-carb vegetables

And boy are there plenty! Read the next section for examples to add to your meals.

Keto diet vegetables 

Veggies aren’t off the menu – yay!

Ketogenic diet vegetables include:

1. Cauliflower

Half a cup of chopped raw cauliflower contains 5.3g of carbs.²³

2. Cabbage

Half a cup of cabbage contains 4.1g of carbs.²⁴

3. Spinach

Half a cup of spinach contains 6.8g of carbs.²⁵

4. Courgette

One medium courgette contains 5.8g of carbs.²⁶

5. Lettuce

Two cups of shredded lettuce contain 3.1g of carbs.²⁷

6. Cucumber

One medium cucumber contains 7.3g of carbs.²⁸

7. Asparagus

Five spears of asparagus contain 3.1g of carbs.²⁹

8. Kale

One cup of chopped kale contains 7.3g of carbs.³⁰

These are all keto dieters go-to thanks to their low carb content.

Cook your veggies in butter and drizzle salads with oil to increase the fat content. Peppers, green beans, broccoli and sprouts also are a fave, but do have a higher carb content.

Keto diet fruit 

As well as vegetables, there are also many different low-carb fruits you can include in your keto diet plan.

1. Raspberries

Half a cup of raspberries contains 3g of carbs.³¹

2. Blackberries

Half a cup of blackberries contains 4g of carbs.³²

3. Strawberries

Eight medium-sized strawberries contain 6g of carbs.³³

4. Plum

One medium-sized plum contains 7g of carbs.³⁴

5. Kiwi

One medium-sized kiwi contains 8g of carbs.³⁵

6. Cherries

Half a cup of cherries contains 8g of carbs.³⁶

7. Blueberries

Half a cup of blueberries contains 9g of carbs.³⁷

8. Clementine

One medium-sized clementine contains 9g of carbs.³⁸

9. Cantaloupe

One cup of chopped cantaloupe contains 11g of carbs.³⁹

10. Peach

One medium-sized peach contains 13g of carbs.⁴⁰

Keto diet snacks 

Stuck for ideas on the snack front? Check out our keto diet snack ideas below for some inspiration.

1. Nut butter balls

A 40g serving contains 4g of carbs.

2. Egg and broccoli mini muffin

One mini muffin contains 1.4g of carbs.

3. Cheese and pepper strips

A 28g serving of cheese and one pepper contains 4.7g of carbs.

4. Nuts

A 28g serving contains 3.9g of carbs.

5. Cheese stuffed mushrooms

A serving of four cheese stuffed mushrooms contains 3g of carbs.

6. Beef jerky

A 20g serving of beef jerky contains 2g of carbs.

7. Boiled eggs

Two large boiled eggs contain 1.2g of carbs.

8. Dark chocolate

A 28g serving of dark chocolate contains 12.5g of carbs.

9. Popcorn

A 28g serving of popcorn contains 21g of carbs.

Keto diet drinks 

Below are our top keto diet drinks...

1. Black tea

One cup of black tea contains 0.7g of carbs.⁴¹

2. Black coffee

One cup of black coffee contains 0 carbs.⁴²

3. Green tea

One cup of green tea contains 0 carbs.⁴³

4. Naturally sweetened diet drinks

One cup of a naturally sweetened beverage like Zevia contains 0 carbs.⁴⁴

5. Sparkling water

One cup of sparkling water contains 0 carbs.⁴⁵

6. Lemon juice

Half a cup of raw lemon juice and water contains 8.5g of carbs.⁴⁶

7. Lime juice

Half a cup of raw lime juice and water contains 10g of carbs.⁴⁷

8. Celery juice

One cup of celery juice contains 7g of carbs.⁴⁸

9. Coconut water

One cup of coconut water contains 8.9g of carbs.⁴⁹

10. Unsweetened almond milk

One cup of unsweetened almond milk contains 1.1g of carbs.⁵⁰

11. Unsweetened coconut milk

One cup of unsweetened coconut milk contains 0.6g of carbs.⁵¹

Keto diet foods to avoid

Reduce or eliminate the following foods if you’re eating keto:

1. Sugar-laden foods

Fruit juices, fizzy drinks, cake, ice cream, smoothies, sweets, milk chocolate, etc. are a no-go.

2. Starches and grains

Rice, pasta, cereals and other wheat-based foods should be avoided at all costs.

3. Fruit

Avoid most fruits except low-glycemic impact berries like blueberries and strawberries – as well as the fruits we listed above.

4. Legumes and beans

Chickpeas, kidney beans, black beans, lentils, peas, etc.

5. Tubers and root vegetables

White potatoes, sweet potatoes, parsnips, carrots, etc.

6. Diet / low-fat products

Avoid these as they are normally processed and high in carbs.

7. Some sauces and condiments

Check the nutritional information of your favourite sauces and condiments because some could be very high in sugar.

8. Unhealthy fats

Cut back on your use of processed vegetable oils, mayonnaise, etc.

9. Sugar-free ‘diet foods’

Sugar-free products are highly processed and tend to be high in sugar alcohols, which have been seen to affect ketone levels so it’s best to avoid.

10. Alcohol

Most alcohol has a very high carb and sugar content, which means it would throw you straight out of the ketosis state.

Do I need to take ketosis supplements?

As your body is doing the work itself, ketosis supplements aren’t required on a ketogenic diet.

However before you do any exercise, it’s important to ensure you’re eating enough, both calories and fat.

If you already supplement your diet with sports products, check the carbohydrate content on the labels.

There are also specific keto diet friendly supplements that you could also try to fuel your next workout.

7 side effects of the keto diet

Keto flu is the most common side-effect people experience when adapting to the ketogenic diet.

To tackle keto flu, make sure you drink plenty of water and get plenty of sleep. Here are some side effects to be aware of:

1. Symptoms like fatigue and fogginess are common in the first few days as your body gets used to eating little-to-no carbohydrates.⁵²
2. More symptoms of keto flu include diarrhea, constipation and vomiting.⁵³

Less commonly however, you may experience:

3. Nausea
4. Increased hunger
5. Worsened exercise performance
6. Digestive discomfort
7. Issues with sleeping

Is the keto diet suitable for everyone?

While keto works well for a lot of people, it’s not necessarily the best diet for everyone.

People who are pregnant or breastfeeding, have type-1 diabetes, have pre-existing liver conditions or have undergone gallbladder removal shouldn’t go on a keto diet.

Are there different types of ketogenic diets? And what ketogenic diet is best for me?

Yes! There are a few different versions of the ketogenic diet, including:

• SKD – Standard ketogenic diet: this is the typical keto diet that people are referring to when they talk about ketogenic diets. It’s a super low-carb, high-fat and moderate-protein diet that typically contains 5% carbs, 20% protein and 75% fat.11
• CKD – Cyclical ketogenic diet: a favourite for bodybuilders and athletes who may struggle to get all the energy they need to train effectively through a keto diet, the CKD diet adds in periods of ‘carb refeeds’, e.g. they follow the standard keto diet for 5 days then allow themselves 2 high-carb days, then repeat the whole cycle again.
• TKD – Targeted ketogenic diet: another favourite for athletes and those with a strenuous training routine, the targeted ketogenic diet allows you to eat some carbs around your workouts.
• High-protein ketogenic diet: just keto with more protein, this version of a keto diet typically advises you to replace some of your dietary fats with protein. The ratio often looks like: 60% fat, 35% protein and 5% carbs

Most of the things we will discuss in this article will be referring to the standard ketogenic diet.

However, as you can see above, many of the main principles of keto apply to all of these diets so you should be able to adapt any information quite easily to each one.

Can you do a vegan or vegetarian keto diet?

Yes! The main source of fat in a standard keto diet is from meat and oily fish, however vegetarians can do the keto diet by substituting with increased dairy products, eggs and meat alternatives.

If you opt for a vegan keto diet, make sure to eat the following ketogenic diet foods:

• Vegan ‘meat’: tofu, tempeh, seitan, pea protein faux meats, soya faux meats and any other low-carb, high protein vegan ‘meat’
• Mushrooms: try to find ‘meaty’ varieties like king oyster, shiitake, chestnut, etc. but normal ones will do fine too!
• Leafy greens: kale, spring greens, spinach, etc.
• Above ground vegetables: cauliflower, courgettes, broccoli
• High-fat alternatives to dairy: replace dairy with vegan coconut or soya-based yoghurts, creams and cheeses
• Low-glycemic impact berries: raspberries, blackberries, blueberries and similar
• Sea vegetables: kelp, dulse, bladderwack, etc.
• Fermented foods: kimchi, sauerkraut and other pickled vegetables

Meat-eaters can eat all of these foods too, of course! Read more about what you can eat on a ketogenic diet as a vegan here.

Can you exercise on the keto diet?

Yes, you are able to exercise while following the keto diet. However, if you’ve just made the transition to keto, you may find that your body may struggle to complete certain activities.

When taking part in high intensity exercises like circuits and sprinting, your body looks for something to burn quickly, which is usually carbohydrates.

And, seeing as the keto diet limits the amount of carbs, you may find high intensity workouts a little more difficult. Avoid HIIT and circuits while your body gets used to restricting carbs.

Low intensity cardio burns more fat to fuel your body. Try swimming, jogging and cycling.  If cardio isn’t your thing, strength training is also an option – try fewer reps with lighter weights to see how you fair.

The final say

The keto diet is popular for a reason.

With fast results and a range of benefits, it can help people along their health journey – but it’s not necessarily for everyone.

Not sure if the ketogenic diet plan is for you? Discover which diet is for you here.

Or if you have a condition that could complicate matters, it’s best to consult your GP for professional advice before giving it a go.

Last updated: 11 November 2021