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Ketogenic Diet, the Pros and Cons you need to know

Leslie Wong, HK BioTek Intern

Ketogenic Diet (Keto Diet) is a popular diet recently with its reputation in losing weight rapidly. There had been some advantages and risks discovered on such a diet by people who tried it and by health experts. So before following the keto diet, these are some points you have to know.

The Keto diet is a low carbohydrate-high fat diet which mimics the effects of fasting. This change of intake in macronutrients can induce ketosis, a metabolic state in our body that changes the primary source of energy from carbohydrates to fats to cause fat burning for weight loss. The Keto Diet originated as a medical therapy for neurological disorder, by enhancement of mitochondria, the powerhouse of our cells, to reduce oxidative stress and inflammation.

The proportion of intake of macronutrients in the Keto Diet is about 75% fats, 20% protein and finally 5% carbohydrate. Following is a basic food guide of keto diet:

Types of food to eat: Eggs, poultry, fatty fishes (salmon, mackerel), meat (beef, organ meats), full-fat dairy products (yoghurt, butter), full-fat cheese, healthy fats (coconut oil, olive oil), non-starchy vegetables, condiments (salt, pepper)

Types of food to avoid: Bread and grains (white bread, baked goods, rice, spaghetti), sugary foods (ice cream, sugar, sweetened beverages), starchy vegetables and fruits, alcohol and other high-carb food sources.

Example of a 1-day keto diet meal plan:

Breakfast: Mushroom omelette

Lunch: Tuna salad with celery and tomato

Dinner: Roast chicken with cream sauce, with sauteed greens

Snacks: Cheese roll-ups

Meal plan from Heathline:

Now let us look at the pros and cons of the keto diet.

Pro 1: Rapid weight loss

The Keto diet is well known for its rapidness in reducing weight, especially in obese people, by inducing the feeling of fullness by fats even with low caloric intake. There was a mass study in 2012 which showed statistically significant weight loss in about 19000 patients with BMI over 35 in a 1-month Keto diet treatment, with an average of 10% weight loss, which was evidence of its weight-losing power.

Pro 2: Embracement of fatty foods

An attractive point of keto diet to a lot of people is the embracement of fatty foods, which is restricted in most of the other diet methods (high fiber-low fat diets). People who like fatty foods like dairy products such as yoghurt, butter and cheese would love to follow the keto diet. Organ fats, bacons and condiments are also allowed, which makes keto diet kind of a cheating method in dieting, as the foods allowed are too enjoyable as a weight-loss diet, unlike plant-based diets which emphasize fibrous carbohydrates like starchy vegetables and whole grains which were less rich in flavours.

However, other than its effectiveness and enjoyableness, there are several problems and risks when adopting the keto diet, especially in the long term.

Con 1: Keto flu

Keto diet is a complete change of nutrient intake compared to normal diet. Therefore, several symptoms can happen to people who first adopt the diet, and they are called ‘Keto flu’. Examples are headache, fatigue, nausea, gastrointestinal discomfort, lower energy, etc. A known remedy for such symptoms is the intake of electrolytes.

Con 2: Risk of Cardiovascular diseases

Keto diet emphasizes high intake of fat, but it is important to choose fatty foods wisely, as saturated fats and trans-fats can do harm to us by raising our LDL level. Low-density lipoprotein (LDL) is the ‘bad’ cholesterol many people are talking about in recent years, as it is discovered as a major reason for atherosclerosis (build-up of plaque in artery walls), and hence cardiovascular diseases. Therefore, it is important to limit saturated fats (butter and meats) and trans-fat (fried foods) when adopting the keto diet, and have more unsaturated fats instead, common sources of unsaturated fats are olive oil, fishes, nuts and avocados.

Con 3: Unsustainability

Keto diet is not a sustainable diet intervention, as long term limitation of carbohydrate can be difficult to a lot of people, making the diet hard to follow in the long run. Also, although keto diet performs well in short term weight loss, it does not as good in long term when compared to other dietary intervention. A study in 2020 tested out the weight loss performance of participants who adopted the keto diet and the low-glycemic index(GI) nutrigenetic diet. Although the keto group did better in the short term (4 months), after more than a year, the group of low GI diet had lost significantly more weight, with improvements in cholesterol profile and blood glucose as well. Looking back at the 2012 mass study of keto diet performance, more than 1 out of 3 patients regained weight after the keto treatment when followed up after a year, some even weighed higher before the treatment. Other than the chance of bouncing back in weight, the keto diet also lacks carbohydrates and fibrous foods, and micronutrients like vitamin B and C, magnesium and phosphorus, which makes it an unbalanced diet in the long term. This evidence questioned the sustainability and the long term performance of keto diet, with several health concerns being unclear.

Are you really in a rush?

To conclude, the keto diet is a modern way of dieting to lose weight effectively in the short term, but there are problems of unsustainability and several health risks being unclear in the long term, under a lack of controlled clinical studies. Therefore, it is recommended to consult your doctor before following the keto diet to see if you are suitable for it. In the meantime, there are many more sustainable and scientifically proven dietary interventions to adopt like the Mediterranean diet which is the gold standard of diet in recent years. It emphasizes low saturated fats and high unsaturated fats, with rich fibrous food, which has gained a good record of losing weight in studies, and evidence in reducing risk of getting cardiovascular diseases. So, if you are not in a rush of losing weight, consider a safer and healthier diet!


Cappello, G., Franceschelli, A., Cappello, A., & De Luca, P. (2012). Ketogenic enteral nutrition as a treatment for obesity: Short term and long term results From 19,000 patients. Nutrition & Metabolism, 9(1), 96. doi:10.1186/1743-7075-9-96

How to get started with the ketogenic diet. (2021, March 30). Retrieved June 17, 2021, from

Kubala, J. (2018, August 21). A keto diet meal plan and menu that can transform your body. Retrieved June 17, 2021, from

Mahan, L. K., & Raymond, J. L. (2016). Krause's food & the nutrition care process. St. Louis (Mo.): Elsevier.

O'Neill, B., & Raggi, P. (2020). The ketogenic diet: Pros and cons. Atherosclerosis, 292, 119-126. doi:10.1016/j.atherosclerosis.2019.11.021

Sáenz de Pipaón, M., Flores-Rojas, K., Gil, A., & Gil-Campos, M. (2020). Commentary: Consumer reports of “keto flu” associated with the ketogenic diet. Frontiers in Nutrition,7. doi:10.3389/fnut.2020.00113

Vranceanu, M., Pickering, C., Filip, L., Pralea, I. E., Sundaram, S., Al-Saleh, A., . . . Grimaldi, K. A. (2020). A comparison of a ketogenic diet with A LowGI/nutrigenetic diet over 6 months for weight loss AND 18-month follow-up. BMC Nutrition, 6(1). doi:10.1186/s40795-020-00370-7

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