• Customer Service Team available now: Mon-Fri 8:00-17:00
  • Private & confidential service
  • Genuine medication
  • All-inclusive service - No hidden fees
  • Next day delivery

Keto: does it really work for weight loss?

The keto diet is a popular diet plan for weight loss. It is a low-carbohydrate and high-fat diet which alters your metabolism and promotes weight loss. It’s a strict diet and not for everyone, but does it really work for weight loss? Keep reading to learn more about keto, how to start and whether it’s right for you.

Medically reviewed by Dr. Caroline Fontana Written by our editorial team Last reviewed 29-10-2023

What is a ketogenic diet?

The ketogenic diet, or keto for short, is a diet that focuses on a very low-carb and high-fat intake. This means that instead of relying on sugar for energy, which comes from carbohydrates, your body burns fat for fuel instead.

Keto diet written on a piece of paper surrounded by keto foods

Ketosis is a metabolic state that occurs when there is no sugar for energy. So instead, your liver breaks down fats to use as energy. This produces a chemical called ketones or ketone bodies which act as fuel for your body.

How do you know you’re in ketosis?

You don’t enter ketosis automatically when you start the diet. For most people who follow the diet closely, it takes a few days to reach ketosis.


When you reach ketosis, you’ll experience some side effects often called keto flu. Some symptoms of keto flu include:

  • Odour changes - When your body goes into ketosis, it releases other chemicals that your body doesn’t need. These are released through your urine, sweat or breath, which alters the smell.
  • Tiredness - It takes a while for your body to get used to the diet, so you may feel more tired than usual.
  • Constipation - A keto diet has less fibre and water content which can make it harder to use the bathroom.
  • Diarrhoea - Others have the reverse problem. For some, the body doesn’t digest all the fats in your diet, which can cause oily or loose stools.
  • Muscle cramps - The diet causes imbalances in your mineral levels. Low levels of magnesium, potassium or sodium can cause cramping.
  • Mood changes - Your brain needs glucose for essential functions, so a lack of carbs can affect your mood and concentration.

Keto flu symptoms should last for around one week for most people. In rarer cases, some may experience symptoms for up to a month.

What are the different types of ketogenic diets?

The standard keto diet involves a ratio of 70-75% fat, 20% protein and around 5-10% carbs. That’s around 20-50g of carbs, 40-60g of protein and no set limit for fat.

ketogenic diets-infographic

However, there are several types of keto diet that you can try for weight loss.

  • Cyclical Ketogenic Diet (CKD) - sometimes known as carb backloading, involves days where more carbs can be eaten. A typical split maybe 5 ketogenic days followed by 2 days of a higher carb intake.
  • Targeted Ketogenic Diet (TKD) - similar to CKD, but involves eating carbs on days that you exercise.
  • High Protein Ketogenic Diet - as the name suggests, includes more protein than a standard keto diet. People usually eat 35% protein, 60% fat and 5% carbs.

These keto variations are best suited for people who exercise and need more carbs as a source of energy than those who don't exercise.

Low carb vs keto diets

While both diets require you to eat a low amount of carbs, the keto diet is much more restrictive. Depending on the type of keto, you can only eat around 20-50g of carbs a day. On a low-carb diet on the other hand, the amount of carbs you consume is more flexible. You can eat as much as 150g carbs today and it is still low carb.

What foods should you eat on keto?

While the keto diet emphasises the need for more fats in your diet, you should prioritise healthy fats as they have a lot of additional nutrients.

Foods you should incorporate more of include:

  • seafood and fish (e.g. salmon and mackerel)
  • lean meats (e.g. chicken and turkey)
  • avocado
  • nuts and seeds
  • eggs
  • Greek yoghurt

You can also eat fatty meats (e.g. red meats) and cheese, but in moderation. These foods are high in saturated fats and salt, which can raise your cholesterol levels and affect your overall heart health.

Keto meals

You must also eat vegetables and fruit. They are low-carb but have a lot of essential nutrients.

Non-starchy vegetables and fruit include:

  • broccoli
  • cauliflower
  • courgette
  • green beans
  • bell peppers
  • berries (e.g. blueberries)

While your carb allowance is minimal on keto, allotting it for fruit and vegetables is the best way to plan your diet.

What are some foods to avoid on keto?

The main food groups that you should avoid on keto are bread, wholegrains and snacks.

While you don’t have to overly restrict the foods you enjoy, you only have a small number of calories to spend on carbs each day - so choose wisely. For instance, one banana has 28g of carbohydrates in it.

High-carb foods to avoid on keto include:

  • breaded goods
  • rice and pasta
  • cereals
  • oats
  • pastries
  • sweet treats (e.g. chocolate)
  • savoury snacks
  • fizzy drinks
  • fruit juices
  • honey
  • jam
  • bananas

This may sound like a terrifying list, but meal planning nutrient-dense and tasty meals are the best way to forget the carb cravings.

Keto diet recipes

If you’re still not sure what a day of eating on keto looks like, here is some recipe inspiration for you.

For breakfast:

  • Mushroom omelette
  • Scrambled eggs with spinach and fresh herbs
  • Eggs and avocado

For lunch:

  • Baked salmon and asparagus
  • Ham, mushroom and spinach frittata
  • Smoked salmon and cream cheese

For dinner:

  • Roast meat and vegetables
  • Prawn, coconut and tomato curry
  • Thai style salad with broccoli rice

There are also plenty of keto-friendly snacks available for between meals. Make sure to check the ingredients list to make sure it is low-sugar before buying it.

What are the health benefits of keto?

When done correctly, a ketogenic diet can have several health benefits.

Keto has been historically used to help treat epilepsy Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source . However, among the general population, the primary benefit is weight loss. One study Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source found that obese patients lost 8.5kg after 6 months of keto, over 4kg more than those who ate a low-fat diet.

Overweight people lose up to 8.5kg on 6 months of keto.

Doing keto can also help reduce several complications of obesity.

It can also help with blood sugar management as carbohydrates spike blood sugar levels the most out of any food group. One study Trusted source Nutrition & Metabolism Peer-reviewed Journals Go to source found significant improvements in blood glucose levels and insulin resistance in those with diabetes after 6 months of keto. This can reduce your risk of heart disease and thrush infections.

As well as blood sugar levels, studies Trusted source PubMed Government Source Database of Biomedical Research Go to source have shown that a keto diet can improve blood pressure and cholesterol levels.

Some interesting findings Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source also show that eating more healthy fats can improve mental performance. Healthy fats from fish and nuts are high in omega-3. Increasing the amount of omega-3 in your diet has been shown to boost DHA levels, an important nutrient for cognitive function.

What are the disadvantages of keto?

While keto can have some benefits, it’s not for everyone.

  • It is a restrictive diet - The diet can be difficult for many. Not getting it right or obsessing over what you eat can affect your mental health and dieting habits in the long term.
  • It can raise cholesterol if not done correctly - Many people assume that the high-fat allowance means you can eat a lot of unhealthy saturated fats, which can spike your cholesterol.
  • Can cause an imbalance in nutrients - It is easy on keto to not eat enough nutrients you get from carbohydrates such as fruits and vegetables.
  • Liver and kidney problems - Eating high levels of fat and protein mean your liver and kidney have more to metabolise.
  • Frequent constipation - The lack of carbohydrates means you probably will not get enough fibre, an important nutrient for healthy and regular bowel movements.

Even doing keto correctly can still put you at risk of some of these adverse effects, so it’s important to consider whether keto is safe before trying it.

Is keto safe?

A ketogenic diet, while uncomfortable, is not dangerous for most people. However, some people could be more likely to experience side effects and should not do keto.

Do not follow a keto diet if you:

  • have an eating disorder
  • have type 1 or type 2 diabetes
  • are pregnant or breastfeeding
  • have hypothyroidism (underactive thyroid)
  • have gallbladder problems or no gallbladder
  • have gut or digestive issues
  • are vegan or vegetarian

If you have any medical conditions and you’re not sure if this list applies to you, consult a healthcare professional before going keto.

How do you start a ketogenic diet?

Now you know more about keto and want to give it a go, where do you start? Before jumping in, there are some vital steps for beginners.

Female hand writing meal plan on clipboard surrounded by healthy foods
  1. Plan your meals - Find some keto-friendly meal ideas that you like. Having a keto meal plan means you won’t go above or below the allotted calories for each food group.
  2. Tell your family or the people you live with - Share with them your goals, what you can eat and how they can accommodate you.
  3. Pick a good time to start - Keto flu can make you tired and uncomfortable for the first week. Pick a week where you have less to do so you can take care of yourself and adjust to the diet.
  4. Cook most of your meals - Knowing what goes into your meals is the key to keto success. Eating ready-made food or at a restaurant can mean you’re not eating the correct ratios.
  5. Have a plan for after keto - Keto isn’t a sustainable diet in the long term. Have a future eating plan once you have reached your keto weight loss goal.

Main takeaways

The ketogenic diet, when done correctly, can be an effective short-term diet for weight loss. However, it is a difficult diet and not suitable for some people. You should always check with your doctor before going keto, especially if you have any other medical conditions.

Further reading

Understanding food cravings and how to tackle them

What should I eat to lose weight? Understanding food cravings and how to tackle them

Reviewed by Dr. Caroline Fontana
The flexitarian diet: A beginner’s guide

What should I eat to lose weight? The flexitarian diet: A beginner’s guide

Reviewed by Dr. Caroline Fontana
A complete guide to binge eating: what you need to know

What should I eat to lose weight? A complete guide to binge eating: what you need to know

Reviewed by Dr. Sarah Donald
The Mediterranean diet: Does it work for weight loss?

What should I eat to lose weight? The Mediterranean diet: Does it work for weight loss?

Reviewed by Dr. Sarah Donald
12 nutritionist tips to lose weight

What should I eat to lose weight? 12 nutritionist tips to lose weight

Reviewed by Dr. Sarah Donald
How many calories should I eat a day?

What should I eat to lose weight? How many calories should I eat a day?

Reviewed by Dr. Plauto Filho
What is intermittent fasting and does it work for weight loss?

What should I eat to lose weight? What is intermittent fasting and does it work for weight ...

Reviewed by Dr. Caroline Fontana
Fill out a short
medical form
Doctor issues
Medication sent
from pharmacy