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Healthy living,  Nutrition

Does the keto diet really work for weight loss?

Since keto diet hype, many people have been asking me about a ketogenic diet. Is it safe? Would you recommend it? Does the keto diet really work for weight loss? My answer is always: It depends. Certainly, nutrition is never black and white, it always depends on the context.

In the Internet you can find information that keto diet will help you lose weight fast. But there are so many nuances and different things to consider, that as a qualified dietitian (and because I am tired of repeating myself), I will try to explain this diet in details.

Ketogenic Diet is Not a New Invention

Ketogenic diet was originally developed in 1920s to treat intractable epilepsy. Before that, they used starvation as a treatment for epilepsy, but thankfully Dr. Russel M. Wilder found out that that a specific diet could produce similar benefits to fasting. Therefore, he proposed a diet that produced ketonemia, which we now call classic ketogenic diet.

Approximately 30% of patients with epilepsy have the type of disease, that fails to come under control with treatment. That’s why alternative treatments are necessary and one of them is ketogenic diet.

Types of Keto Diet

However, today the keto diet is moving to the mainstream as a low-carbohydrate tool for weight loss and reducing cardiometabolic risk factors. But is it a classic ketogenic diet? Not at all.

Classic ketogenic diet is rich in lipids (90%) and low in carbohydrates and protein, in order to produce ketosis and simulate a starvation state. It is a rigid diet, mathematically and individually calculated, therefore it needs to be medically monitored. In addition, it has a lot of adverse effects: dehydration, hypoglycemia, lethargy, constipation, elevated total cholesterol and weight loss. Yes, you read it right, it is an adverse effect for the patients treating epilepsy with a diet.

However, nowadays in research and in real life diets labeled as “ketogenic” vary widely. Mostly it is a modified ketogenic diet or modified Atkins. It doesn’t mean it’s not effective, but it’s not the same thing. Your ketone production may not be the same depending on how you’re following the diet.

Modified Atkins diet contains around 65% fat, 25% protein, and 10% carbohydrate, but it’s not a rule. It can also be modified to be lower in fat and higher in protein, that’s why we should’t call it „keto“ at all.

How It Works

Ketogenic diet promotes a “pseudofasted” state. After three to four days of fasting or following a very low-carbohydrate diet, the body, deprived of dietary sugar and starch, reduces insulin secretion and switches to primarily burning fat for fuel. It leads to formation of ketones in a process known as ketogenesis. Ketones can cross the blood-brain barrier, providing fuel to the typically glucose-hungry brain as well as to other tissues (1).

Weight Loss Benefits

So, does the keto diet really work for weight loss? The answer is: YES. And it is popular because you can see results in a short amount of time.

It happens mostly, beacuse when carbohydrates are restriced, the body rapidly excrete sodium and fluids. So during the first few days on keto diet you are loosing water, it‘s not fat. But you can see the results fast and that’s what matters.

Of course your not loosing only water, keto diet significantly elevates fat burning. Cravings and hunger are reduced and people don’t need to eat frequent meals every few hours, which is the case for many on low-fat diets. Calorie restriction is therefore easier and weight loss happens with much less effort. And this probably the most important aspect, the calorie deficit. This is what all the diets and weight loss is about.

Research also shows benefits for improving insulin sensitivity and glycemic control, so it’s beneficial for type 2 diabetes mellitus or prediabetes, although the mechanisms are not clear (2).


Firstly, consult with the specialist if you can be on keto diet. It is contraindicated in patients with pancreatitis, liver failure, disorders of fat metabolism and many other diseases. It’s also not recommended during pregnancy. Make an appointment with a dietitian to make sure you won’t hurt yourself.

Pay attention on the quality of fats. Big part of ketogenic diet are fats, remember that they don’t have to be animal fats. Getting more plant-based fats from avocados, nuts, seeds, coconut, and olive oil will supply more micronutrients as well as heart-healthy fatty acids.

Also, watch out for vitamin deficiencies. Ketogenic diets don’t just eliminate sugar and refined carbohydrates, but also whole grains, fruits and starchy vegetables. All of these foods contribute vitamins, minerals, antioxidants, phytochemicals, and fiber.

Measure ketones in your blood, not urine. It isn’t the way to measure blood levels of ketones, because simply spilling a few ketones in urine isn’t indicative of ketosis, In order to check ketones in your blood, you should get Ketone Testing Kit, prick your finger with the lancing device and check the level of ketones in the device.

Listen to your body, if you are overwhelmed or simply feel that keto diet is not for you, leave it off. In addition, the rigidity of the ketogenic diet can become obsessive and lead to disordered eating behaviors.

Be prepared for “keto flu” which can include lightheadedness, fatigue, headaches, nausea, and constipation. Above all, this is the result of the body’s rapid excretion of sodium and fluids as carbohydrates are restricted. Increasing sodium by 1 g to 2 g per day may restore the body’s levels to normal.

The Final Verdict

Certainly, cutting carbohydrates is one of many weight loss strategies that work. What is more, fat and especially proteins curbs your appetite, so it’s easier just to simply eat less.

However, ketosis is not a natural state for the body. We don‘t know much about its long-term effects, probably because it’s hard to stick with the ketogenic diet and people can’t eat this way for a long time.

So, does the keto diet really work for weight loss? It can be a good way to initially help wean off sugars and excess carbohydrates intake, but it may be beneficial to consider making adjustments to find a less restrictive meal plan. Working with your dietitian can help you find a balanced approach that works for you and your lifestyle.

What are your thoughts about the keto diet? Please share your opinion below!


1. Brouns F. Overweight and diabetes prevention: is a low-carbohydrate — high-fat diet recommendable? Eur J Nutr. 2018;57(4):1301-1312.

2. Saslow LR, Daubenmier JJ, Moskowitz JT, et al. Twelve-month outcomes of a randomized trial of moderate-carbohydrate versus very low-carbohydrate diet in overweight adults with type 2 diabetes mellitus or prediabetes. Nutr Diabetes. 2017;7(12):304.