The beginner's guide to the keto diet

What was the most Googled diet worldwide in 2021? Keto, of course. From books to blogs and magazines to morning television, the low-carb, high-fat diet is (quite literally) everywhere you look.

With benefits like weight loss, reduced risk of disease and improved focus, you might be tempted to give keto a go too. The only problem? If you’re a beginner, it’s all a bit confusing. Ketosis what, net carbs who – and, most importantly – how on earth am I supposed to give up carbs? 

We get it, and we’re here to help. Consider this your step-by-step beginner’s guide to going keto: what it is, whether it’s healthy, what you can eat and everything you need to know to get started, safely. Ready, set, keto!

The keto diet basics

The keto diet is a high-fat, low-carb, moderate-protein diet (yep, you’ll need to break up with carbs). The ultimate goal is to reach a fat-burning metabolic state called ketosis, which can be an effective way to lose weight.

How does keto work?

The body uses glucose – which is produced by your body when you break down carbs – as its primary source of energy. But when you eat drastically fewer carbs (under 20g), it switches to plan B: fats. 

Your body begins to break down fats, rather than carbs, for energy. It also produces ketones, a type of chemical that the liver produces when it breaks down fats. The brain uses ketones as an energy source when glucose isn’t available. This is what’s known as ketosis – hence the name ‘keto’.

Thanks to its fat-burning power, evidence suggests that ketosis can help you to lose weight whilst preserving muscle mass: a winning combination for healthy weight loss. 

Getting started on a keto diet

Get started with these 3 simple steps:

• Reduce your daily net carbohydrate intake to 20g or less
• Eat as much fat as you need to feel satisfied (not stuffed)
• Listen to your body and eat when you’re hungry
• Increase the amount of water you drink

What are the keto macros?

To follow a keto diet, you’ll need to eat very few carbs, a moderate amount of protein and enough fat to feel satisfied, but not stuffed. Roughly, this looks like:

• Carbs: 5–10% of your calories
• Protein: 20–35% of your calories
• Fat: 60–75% of your calories

But these percentages are most important for those using keto as a tool to manage symptoms of a neurological disorder or for other therapeutic/medical reasons.

In these cases, maintaining a certain ketone level – which requires a very specific macronutrient ratio – is important. But it’s best to work with a qualified professional to determine what macro ratio is right for you. 

If you’re doing keto for weight loss or improved general health, just try to follow these guidelines:

• Carbohydrates: Limit to 20g or fewer per day
• Protein: Eat a normal/moderate amount – just aim to meet your body’s needs! For most people, this is around 1.2 to 2.0 grams per kg of body weight (Diet Doctor)
• Fat: Eat enough to feel satisfied, not stuffed

…but don’t I need to eat loads of fat?

Fat is an essential part of the keto diet. Whether from food or from your stored body fat, it supplies calories, energy and flavour in the absence of carbs.

But there’s no need to go overboard. If you’re doing keto for weight loss, a portion of the fat your body needs will come from your body. And eating more fat than you need could result in weight gain, even if you eat very few carbs. 

Make sure to add a good serving of fat to every meal. You should aim to feel full, but not absolutely stuffed. There’s no real need to track your fat intake unless you’re following keto for therapeutic reasons.

…and won’t too much protein kick me out of ketosis?

Protein is essential for good health, on or off a keto diet. Not only does it increase muscle mass and strength, but it plays a role in countless bodily processes that you need to survive.

Some people believe that too much protein will take you out of ketosis due to gluconeogenesis (GNG), a process that allows your body to create glucose from non-carb sources, such as protein.

Current evidence suggests that the protein content of your diet doesn’t impact the rate of GNG. As Diet Doctor says, “The most common mistake that stops people from reaching ketosis is not too much protein. It is too many carbs.”

So don’t stress about protein, but don’t skimp on it either. You'll hit the right balance by simply including a serving of protein (meat or fish, for example) with every meal.

So do I need to track my macros?

Tracking your carb and protein intake can be helpful when you’re getting started with keto, but there’s no need to count fat or calories.

Having to track your meals obsessively might make keto (and food in general) feel like a burden. It could also make keto harder to stick to over the long term.

So start by tracking your carb macro and assess your progress from there. In time, you’ll learn what 20g (or less) of carbs looks like per day and how much protein you need at each meal, without having to track.

How do I know if I’m in ketosis?

Ketosis is a metabolic state where your body starts using fats and ketones as its main energy source. The most common signs and symptoms of ketosis are:

• Weight loss
• Bad breath (because ketones leave the body through the breath, as well as urine)
• Thirst
• Reduced appetite (one of the more welcome symptoms!)
• Headache
• Nausea
• Brain fog
• Fatigue

You’ll be pleased to know that most of these symptoms will ease within a few weeks, once your has body adjusted to the dietary change. The reduced appetite, however, should stick around for as long as you’re keto-ing!

Do I need to test for ketosis?

Nope! Unless you’re following a keto diet for therapeutic reasons, there’s no need to test for ketosis.

As Reddit’s ever-growing Keto forum FAQ says, ‘Chase results, not ketones. Testing is not recommended, as it can often serve as a distraction from what is important. More ketones does not mean more weight loss.’

What foods should I eat on keto?

Two words: whole foods. As the keto diet has grown, so too has the availability of ultra-processed keto foods – think bars, bread, cookies and low-carb pasta. But to keep your body healthy and weight stable long-term, following a whole foods keto diet is the way to go.

We’ve evolved to eat, digest and absorb whole foods. They work in synergy with your hunger/satiety hormones, gut microbiome and other systems that help you regulate your body weight and naturally keep you in good health.

Take a look through this keto foods list to get started:

Keto foods to eat

• Fish: Tuna, salmon, cod, bass, trout, prawns etc
• Meats: Beef, pork, ham, lamb, good quality bacon/sausages
• Poultry: Chicken, turkey, duck 
• Eggs
• Full-fat cheese: Brie, camembert, cheddar, goats cheese, mozzarella, parmesan etc
• Cream, butter & lard
• Cooking oils: Olive, coconut or avocado oil
• Nuts & seeds: Almonds, brazils, cashews, chia seeds, flax, pumpkin seeds, walnuts etc
• Leafy greens: Card, chives, kale, lettuce, spinach, rocket, watercress etc
• Non-starchy vegetables: Avocado, asparagus, aubergine, broccoli, cauliflower, celery, celeriac, courgette, green beans, mushrooms, olives, peppers, tomatoes etc
• Low-sugar fruits: Blueberries, blackcurrant, strawberries, raspberries etc
• Low-carb plant milks: Almond, coconut, cashew, pea

Make sure to add Purition to your keto shopping list, too. It’s a healthy keto-friendly meal – think shakes, yoghurt bowls or an instant low-carb porridge – made from natural whole foods.

Every serving contains just 2-4g net carbs per serving, 14g of fat, 6g fibre and 16g protein to keep you full for hours!

Keto foods to avoid

• Cow’s milk
• Sugary fruits: Most fruits, except berries
• Sugary foods: Fruit juice, smoothies, cakes, pastries, ice cream, sweets etc
• Starchy foods: Bagels, bread, beans, grains, flour, muffins, legumes, rice, root vegetables, pasta
• Starchy vegetables: Potatoes, sweet potatoes, carrots, parsnips etc
• Processed oils: Sunflower, rapeseed & vegetable
• Low-fat & diet products: Margarine and low-fat milk/yoghurt etc
• Sugar alcohols: Check labels for sorbitol & maltitol

What can I drink on a keto diet?

• Tea & coffee: Ideally black or with keto-friendly milk, unsweetened
• Water & sparkling water: Lots of it!
• Dry red & white wine: In moderation
• Spirits like vodka & gin: In moderation, best mixed with tonic or soda & lime/lemon

Do I need to take supplements on a keto diet?

Not necessarily. A whole foods keto diet is nutrient-dense and nutritionally complete. Even so, it’s best to take a good quality multivitamin (such as Purition’s Multi Nutrient) to ensure all your bases are covered, especially when you’re getting started.

One keto supplement to consider is electrolytes. Keto diets are often deficient in three of them: sodium, potassium, and magnesium. This is because the keto diet has a diuretic effect: when you drastically cut back on carbs, you lose more electrolytes through your urine.

When your electrolyte levels drop, you might not feel your best. Symptoms include fatigue, weakness, headaches, muscle cramps and heart palpitations. While electrolyte supplementation is an option, Diet Doctor recommends trying a food-first approach:

• Sodium: Be more liberal with salt at meal times
• Potassium: Eat plenty of avocado, mushrooms & leafy greens
• Magnesium: Eat plenty of hemp, pumpkin and chia seeds, mackerel and leafy greens

Health benefits, risks & side effects of the keto diet

Done right (think whole foods, lots of water and avoiding ultra-processed keto products), keto diet health benefits far outweigh any drawbacks.

What are the health benefits of a keto diet?

From weight loss to blood sugar control, regularly achieving nutritional ketosis has been linked with numerous evidence-backed health benefits, namely:

Weight loss

When you deprive the body of carbohydrates (glucose, its primary energy source), it produces ketones from stored body fat for energy instead. When the body begins using fat as its primary fuel – i.e. you become a fat-burning powerhouse – you’ll experience weight loss.

And the research backs it. For example, one study showed that a low-carb diet is more effective for weight loss than a low-fat diet, even when calories are matched. Another stated that “A period of low carbohydrate ketogenic diet may help to control hunger and may improve fat oxidative metabolism and therefore reduce body weight.”.

Lower risk of heart disease

The higher the proportion of ‘good’ (HDL) cholesterol to ‘bad’ (LDL) cholesterol, the lower your heart disease risk.

One of the best ways to increase your levels of ‘good’ HDL cholesterol is to eat plenty of unsaturated fat – which, thankfully, a whole foods keto diet is packed with. That’s why studies show that ‘good’ cholesterol increases, but ‘bad’ cholesterol decreases, when eating a healthy low-carb diet. Winner.

Low-carb diets are also known to reduce triglycerides, which can further reduce your risk of heart disease. Double winner!

Better blood sugar control

When you eat high-carbohydrate foods, your body breaks the carbs into glucose (sugar), which raises your blood sugar levels.

Because the keto diet is low in carbohydrates, it can help to reduce – and even eliminate – large fluctuations in your blood sugar, leading to better blood sugar control overall. 

A recent study compared the effects of a low-calorie diet vs a low-carbohydrate ketogenic diet on type-2 diabetics. And guess what? The ketogenic group achieved ‘normal’ blood sugar levels in just 24 weeks – at a much faster rate than the low-calorie group!

Lowered triglycerides

Triglycerides are a type of fat found in your bloodstream. In the correct amounts, they’re essential for good health. Your liver can make triglycerides, but you also get them from the food you eat.

According to Heart UK, high triglycerides can contribute to the risk of heart disease and other diseases of the heart and blood vessels. Very high triglyceride levels can even lead to serious medical conditions, such as pancreatitis.

The good news? Studies show that very low carbohydrate or ketogenic diets are an effective way to lower triglycerides, which in turn, can help to reduce the risk of heart disease.

What are the risks of a keto diet?

As with most dietary changes, there are a few potential risks to be aware of. Don’t let these keto risks put you off, though – done right, a keto diet is a safe and nutritious option for most.

Digestive issues

Studies show that constipation is apparent in up to 50% of keto dieters.

This may be due to a sudden decrease in fibre due to cutting back on carbs. Fibre increases the size of stools, makes them softer and, generally, keeps the digestive system moving. Put simply, it’s your digestive system’s best friend.

You can prevent keto constipation by simply eating enough fibre – the British Nutrition Foundation recommends 30g per day. There are plenty of keto-friendly sources, including above-ground vegetables like leafy greens, broccoli, peppers, courgettes and cauliflower, as well as nuts and seeds.

Dehydration can contribute to constipation, so make sure you’re staying hydrated too. Try to drink at least 2 litres of fresh water every day.

Nutrient deficiencies

You’re likely to need to cut out a large number of foods from your existing diet in order to go keto. The downside? This could put you at a greater risk of nutritional deficiencies.

Some studies have shown that keto diets are more likely to be deficient in calcium, vitamin D, magnesium and phosphorus than a ‘standard’ diet.

This does depend on the nutritional quality of your keto diet. If you base the majority of your diet on ultra-processed keto packet foods, you’re more likely to suffer from a deficiency.

But if you focus on eating a wide variety of vegetables, unprocessed meats, fish, berries, nuts and seeds, you’re more likely to get all the nutrients you need.

The keto ‘flu’

Drastically cutting back on carbs can come as a shock to your body.

Studies report that many new-found keto dieters report low energy, headaches, brain fog, low mood, constipation and nausea within the first few weeks of following a keto diet. No, thank you!

This is thought to be caused by dehydration and electrolyte imbalances that occur as your body adjusts to the new diet.

To combat the keto flu, Diet Doctor recommends:

• Increasing your salt & water intake
• Eating more fat
• Taking it easy with exercise
• Eating until you’re no longer hungry

If all else fails, it’s wise to take a slower approach to the keto diet transition. Instead of instantly cutting down to 20g carbs per day, why not start at 75, then 50, and eventually tailor down to 20g? This should help to make the transition easier and reduce your keto flu symptoms.

Who should avoid a keto diet?

Anyone with the following conditions should check with their GP or healthcare provider before starting a keto diet:

• IBS
• Diabetes
• Osteoporosis
• High blood pressure
• Kidney disease/other kidney problems

Pregnant or breastfeeding? It’s not the right time to try keto. If you need to restrict carb intake, it’s recommended that you consume at least 50g carbs per day. Make sure to discuss any diet changes with your healthcare provider before getting started.

Beginner’s tips for the keto diet

Now you know the keto basics, you’re probably raring to get started. But before you do, check out our last few beginner’s keto tips to ensure your new diet is easy-to-follow, enjoyable and ultra-healthy, too!

1. Aim for a whole food keto diet

A healthy keto diet isn’t as simple as cutting out carbs and hoping for the best.

To support your long-term health and get all the nutrients you need, eating plenty of whole foods (whilst minimising ultra-processed foods) is key.

Whole foods are foods that haven’t been overly processed or refined, such as veggies, good quality meat and poultry, fish, nuts and seeds.

Ultra-processed foods are foods that have been highly refined and contain barely any fibre, vitamins, minerals and other essential nutrients that your body needs to stay healthy. Think sweets, ready meals, keto ‘pasta’ and ‘bread’, as well as most ‘keto’ shakes and bars.

Remember that consistency beats perfection. If you eat whole foods for the majority of the time, the occasional processed meal or treat is nothing to worry about!

2. Start meal planning

If you get home from a long day at work and don’t have a keto-friendly meal planned, it’s easy to fall off track. That’s why the key to any diet change is planning ahead.

Sit down with a notepad or meal planner and write down what you’ll eat for each meal for the next few days – and what ingredients you need to make those meals. Then simply head out to the shops and buy the ingredients you need. That’s it!

Most people try to meal plan weekly, but there are no rules. If you think meal planning every 3, 5, 10 or 14 days will work better for you, try it that way instead. There’s also nothing wrong with making 2 or 3 keto meal plans and alternating them week by week.

Why not make keto meal planning easier by choosing Purition for breakfast and one of our Wholefood Keto Meal Bars for lunch? That’s 66% of your keto meals sorted.

3. Drink water – lots of it!

Ok, we probably sound like a broken record here – but drinking enough water is really important when you’re getting started on a keto diet.

This is because carbs are turned into glycogen and stored with water in the body. In fact, for every gram of glycogen your body stores, it’ll store 3–4 grams of water. When you deplete your glycogen (carb) stores, you also lose the water that was stored alongside it.

So drink up! It’s a good idea to increase your fluid intake, especially during the first few weeks of keto. Aim for at least 2 litres every day – but listen to your body and drink even more if you feel you need it.

4. Plan ahead if eating on the move

It can be difficult to find keto-friendly food on the go. Most meal deals aren’t keto-friendly and grabbing cold cuts, cheese or olives from the deli section can get expensive quickly.

If you know you’ll be out all day, it’s best to prep your lunch the night before so you don’t get caught off guard. Even easier? Make an extra serving of your dinner and pop it in a container to take with you for the day ahead. 

Looking for an easy keto lunch or snack on the go? Try KetoTHIS Meal Bars. Unlike most other keto bars, they’re made with real, whole food ingredients like nuts and seeds, with no artificial ingredients whatsoever. They’re the stress-free way to stick to your keto diet on the go! 

5. Join the keto community

Making yourself a part of the keto community is a great way to stay motivated and pick up new tips and recipes. There are so many seasoned keto-ers who’re happy to help you out, as well as countless other newbie keto dieters in the same boat as you!

Have a search online for Facebook groups, Reddit communities and Instagram hashtags to start getting involved. In some areas, there are even local keto groups that you could join.

6. Don’t be too hard on yourself

Change doesn’t happen overnight. It’ll take time to adjust your habits, get into the swing of keto and feel fully comfortable with your new diet.

You might lose willpower a week or a month in and fall off track. Perhaps you’ll misread a label and accidentally eat something with too many carbs. Or maybe you’ll choose a non-keto meal at a restaurant because choices are limited.

But guess what? All of those predicaments are totally fine. Don’t beat yourself up over small mishaps or pressure yourself to be perfect from the get-go. If you slip up, don’t stress – just get back to it and start again.

7. Try Purition

Need an easy keto breakfast or lunch? You’ll love Purition. Purition is a nutrient-rich, low-carb, high-fat meal, ready in under 30 seconds.

Every serving contains just 2-4g net carbs per serving, with around 14g of fat, 6g fibre and 16g protein and tons of naturally-occurring vitamins to help you stay healthy and happy on a keto diet.

It’s ultra quick and convenient, making it easy to minimise carbs and stay on track with your keto diet when you’re busy. And by choosing Purition for your keto breakfast or lunch (or both!), you’ll have far less tracking to keep on top of!

Find out more about using Purition support a keto diet.

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