The keto diet is a weight loss programme centered on eating low-carb, high-fat foods. It’s gained significant popularity over recent years after claiming you can eat all the fat you like and never feel hungry again – all while losing weight.
But how does the keto diet actually help you lose weight? And more importantly: how can you tell if it’s the right weight loss programme for you?
In this article, we’ll cover the ins and outs of the keto diet, including any benefits and potential health risks to be aware of, to uncover whether or not it really works.
What is the keto diet?
The keto diet is a low-carb and high-fat diet. Though it may seem like a fairly modern trend, the keto diet has been around since the 1920s and was originally prescribed as a method for reducing seizures in pediatric patients with epilepsy. However, while still used for that purpose today, the keto diet is now used mostly as a weight loss tool.
It requires people to significantly reduce their carbohydrate intake and replace it with fat. Your body responds to this reduction in carbs by putting itself into a metabolic state known as ‘ketosis’.
During ketosis, the body becomes highly efficient at burning fat for energy, which can result in weight loss.
There are a few different versions of the keto diet. These include:
Standard ketogenic diet: Involves a very low-carb, moderate-protein, and high-fat intake. Food will typically be balanced between 70% fat, 20% protein, and 10% carbs.
Cyclical ketogenic diet: This version allows for some high-carb days. For example, a person might have five keto days followed by two high-carb days.
Targeted ketogenic diet: This diet allows people to add extra carbs to their diet around workouts.
High-protein ketogenic diet: This version is similar to the standard keto diet, but includes more protein. It usually follows a ratio of 60% fat, 35% protein, and 5% carbs.
Only the standard and high-protein keto diets have been studied extensively. The cyclical or targeted ketogenic diets are generally more advanced methods; mostly used by athletes or bodybuilders.
So, even though many of the same principles apply to other versions of the keto diet, the information in this article mostly applies to the standard keto diet.
What is ketosis?
Ketosis is a metabolic state where the body turns to fat for fuel instead of carbohydrates. Ketosis occurs when a person significantly reduces their carbohydrate intake as this limits the body’s supply of glucose (sugar) – which is the main source of energy for cells.
The most effective way to enter ketosis is to follow a ketogenic diet. This generally involves limiting your carbohydrate intake to around 20-50g per day, and filling up on fat sources like meat, eggs, fish, nuts, and healthy oils instead.
Moderating your protein consumption is important for ketosis too, because protein is also converted to glucose when consumed in high amounts. If this happens, it can easily slow down your transition into ketosis.
When it comes to determining whether you’ve entered a state of ketosis, blood, urine, and breath tests can be used to measure the amount of ketones in your body. Ketone tests are available to buy on Amazon.
Certain symptoms can also indicate whether you’ve entered ketosis. These include increased thirst, a dry mouth, frequent need to urinate, and reduced appetite.
Is the keto diet effective for weight loss?
Research has shown that the keto diet can result in substantial weight loss and may be as effective as low-fat diets.
For example, this scientific review found that following a very low-carb keto diet was slightly more effective for long-term weight loss than a low-fat diet. Those who followed the keto diet lost on average two pounds (0.9kg) more than those who followed a low-fat diet.
Plus, due to the high-fat intake, the keto diet can be very filling and many people find they lose weight without having to track calories.
The keto diet for diabetes and prediabetes
Diabetes is caused by changes in metabolism, high blood sugar, and impaired insulin – and science has drawn a close link between adult obesity and type 2 diabetes. Since the keto diet can help you lose fat, it can be beneficial for people with conditions like type 2 diabetes, prediabetes, and metabolic syndrome.
One study, which involved 349 people with type 2 diabetes, found that those who followed a keto diet lost an average of 26.2 pounds (11.9kg) over the course of two years. Participants also experienced improved blood sugar management, which meant their use of blood sugar medications also decreased throughout the study. Additional research discovered that the keto diet improved insulin sensitivity by an impressive 75%.
For more information on the benefits of eating fewer carbs for diabetes, have a read of this guide to healthy low carb eating with diabetes by Healthline. Alternatively, you might like to try one of these low-carb recipe ideas.
What are some other benefits of the keto diet?
Research has found that the ketogenic diet has various benefits and may potentially help with a range of health conditions. These include:
Heart disease. The keto diet can help improve risk factors for heart disease like body fat, HDL (good) cholesterol levels, blood pressure, and blood sugar.
Alzheimer’s disease. The keto diet may help to improve symptoms of Alzheimer’s and slow progression of the disease.
Cancer. The keto diet is currently being explored as an additional treatment for cancer, because it may help to slow tumour growth.
Epilepsy. Research has shown that the keto diet can significantly reduce seizures in epileptic children.
Parkinson’s disease. One study found that the keto diet helped improve symptoms of Parksinson’s disease, though further research is needed to confirm these findings.
Brain injuries. Some research suggests that the keto diet could improve the impact of significant brain injuries.
Polycystic ovary syndrome. The keto diet can help reduce insulin levels, which may significantly improve polycystic ovary syndrome.
What are the disadvantages of the keto diet?
While research shows that the keto diet has some benefits, there are also various downsides.
Many people experience unpleasant side effects when starting on the keto diet. These symptoms are often referred to as ‘keto flu’ and can include diarrhea, constipation, and vomiting. Other, less common side effects include low energy and mental function, increased appetite, problems sleeping, nausea, reduced exercise performance, and digestive issues or discomfort.
As a result, the keto diet has a relatively high drop-out rate, and static long-term compliance is low. After all, restricting an entire food group usually responsible for providing around 50% of our energy makes it very difficult to stick with long-term.
However, there are also some important potential health risks to be aware of that are associated with following keto diet long-term. These include:
Vitamin or mineral deficiencies. Significantly limiting your carb intake not only means cutting out foods like bread and refined sugar, but you’ll also have to cut back on fruit and vegetables. This can be problematic as fruit and veg are high in antioxidants, and full of vitamins and minerals, so a significantly reduced intake can cause deficiencies.
Digestive issues. Having to cut back on foods like fruit, veg, and wholegrains can also lead to digestive problems as it’s tricky to ensure you’re getting enough fibre.
Reduced athletic performance. Carbohydrates are a key source of energy. So a lack of them can interfere with athletic ability. For example, this study found that participants performed significantly worse in high-intensity running and cycling tasks after four days on a keto diet, compared to those who ate a high-carb diet.
A slight relaxation in rules can cause weight regain. The keto diet is extremely strict, which means any relaxation of the rules can easily reverse any weight loss. As a result, many people following the diet tend to fall into a yo-yo pattern of weight loss followed by weight gain.
- May damage blood vessels. Research has shown indulging in a high-sugar treat while on a high-fat, low-carb diet can actually damage blood vessels. Experts say that this sudden blast of glucose can easily undo some of the positive impacts of the keto diet.
Potential risk to heart health. Experts have raised concern about the health risks of eating a high-fat keto diet long-term. For example, this study found that people on low-carb diets are more likely to develop martial fibrillation – a common heart rhythm disorder that raises the risk of stroke or heart failure.
Increased risk of cancer. Science has shown that a high-fat, low-carb diet can also increase the risk of developing cancer. One study found that people on low-carb diets who ate large amounts of meat and dairy had a higher risk of early death than those who ate carbs in moderation or who consumed mostly plant-based protein.
Who is the keto diet suitable for?
As with any significant diet change, it’s always best to consult your doctor beforehand to understand any potential risks. This is especially important for very low-carb keto diets.
However, some people should avoid dietary restrictions and low-carb diets entirely. These include:
Pregnant or breastfeeding women.
People on hypo-causing medication such as insulin, sulphonylureas, and glinides.
People with a low or very low BMI.
Growing children and teenagers.
People with gallstones.
People who have had their gallbladder removed.
You can read more about keto diet safety guidelines and the risks involved for different groups on Diabetes.co.uk.
Does the keto diet really work?
Whether or not the keto diet works really depends on what your goal is. For example, if you’re someone living with a condition like type 2 diabetes and your goal is to moderate blood sugar levels and other things associated with the condition, then the keto diet can prove very useful.
Equally, if you’re after a quick weight loss method, then research has shown that the keto diet can be an effective method for rapid weight loss. It usually only takes the body around five days to enter a state of ketosis, so results are usually visible early on.
However, if your goal is not only to lose weight, but to keep it off, then the keto diet may not be the ideal solution. Cutting out an entire food group that usually provides around 50% of our daily energy is rarely easy to do. Not only is it difficult to continuously live with such restrictions, but the health risks associated with following keto long-term also make it an unsustainable choice.
As a result, many people find that even though they may succeed at losing weight with the keto diet, they put it straight back on once the diet is over and they return to their regular lifestyle.
Of course, everyone’s experience will be different. However, this yo-yo pattern of weight loss followed by weight gain tends to be the case for the majority of ‘quick-fix’ diet strategies. Instead, the most effective way to achieve, and maintain a healthy weight long-term is often to ditch the temporary diets, and opt for more permanent healthy lifestyle changes instead – like eating a balanced diet and exercising regularly.
For some ideas and inspiration, head over to the fitness and exercise or diet and nutrition sections of our website.
What are your experiences of the keto diet? Do you think it’s a sustainable weight loss method? We’d be interested to hear about your experiences in the comments below.