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Can a Ketogenic Diet Help you Lose Weight?

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You can’t pick up a magazine these days without seeing an advertisement for one diet or another. With so many to choose from it is difficult to know which one will suit you, and which one will work best.

As diet is a cornerstone of any weight loss and lifestyle intervention program this becomes an important decision. Most diets follow a common strategy when aiming to weight – they follow a low fat approach. The ketogenic diet though is very different.

In this article we’ll look at the this diet and whether or not it can help you lose weight.

  • What is the ketogenic diet?
  • Can it help you lose weight?
  • Is it good for health?

What is the Ketogenic Diet?

We can obtain energy from our diet from three different nutrients – carbohydrates, fats and protein. These are referred to as ‘macronutrients‘ as we need them in relatively large amounts. According to the Atwater system each nutrient provides us with the following energy:

  • Carbohydrates – 4kcal per gram
  • Fats – 9kcal per gram
  • Protein – 4kcal per gram

In its simplest terms, this diet is a high fat, low carbohydrate system of eating. It restricts daily carbohydrate intake to 50g or less. This equates to around 10% of total daily energy [1].

Often referred to as a ‘very low carb ketogenic diet‘ (VLCKDs) or simply ‘keto’, it involves taking the calories you would normally eat from carbs and replaces them with fats or protein. The overall amount of daily calories remains the same or if you choose to you can combine it wit a small calorie deficit.

It is claimed that this diet can help you achieve better long-term body weight when compared with individuals assigned to a conventional low fat diet.

Following a very low-carb diet will increase the number of ketone bodies in your blood. These are organic compounds that are produced by the liver and increase in times of carb restriction. As a result, they supply the body’s cells with energy, as opposed to glucose – this process is called ketosis.

Your body does not begin to use ketones as an energy source straight away – it can take around 48 hours for you to transfer from any left over carb stores to ketones. As these compounds use fat stores themselves for energy, it is claimed that in ketosis, fat reserves are readily released and consumed [2] – it works like triggering the fat burning ‘on switch’.


Key Point: The very low-carb diet restricts carbohydrate levels to around 50g or less per day.

The Science – Does a Ketogenic Diet Help you Burn More Fat?

#Study 1: Bueno et al [1]

This is an important study as it used a meta-analysis approach – this is a rigorous type of research where an analysis is conducted on a range of other studies to find a common conclusion – in this case on 13 studies relating to very-low carb diets.

The results of this study found that on the whole, VLCKDs led to significant weight loss. However the authors of the study reported that they were unsure whether it was the reduction in carbs that led to weight loss, or simple just decreasing overall calories and energy expenditure.

#Study 2: Yancy et al [3]

This study, published in the Annals of Internal Medicine, compared the effects of a very low-carb diet program (20g carb per day) with that of a low-fat, reduced-calorie diet in 120 overweight people.

Results showed that retention in the low-carb group was higher – meaning more people stuck to the diet. The same group lost 6.2% more body weight than the low-fat group and lost 9.4kg of fat as opposed to 4.8kg in the low fat group as well. Importantly they lost less muscle too, meaning that their metabolic rate was not reduced in comparison and would not affect weight loss in the long-term.

Importantly, from a health point of view, the low-carb group also saw a favorable change in cholesterol levels, suggesting this diet may even be beneficial for reducing cardiovascular risk.

#Study 3: Westman et al [4]

This study showed that not only was a VLCKD beneficial for weight loss, it also led to better blood sugar profiles and lower medication use in diabetics. 

49 obese, diabetic volunteers were split into one of two groups:

  • Group 1: low carb diet of less than 20g carb per day
  • Group 2: low-glycemic, reduced-calorie diet (500 kcal per day deficit from weight maintenance)

The volunteers in group 1 lost more weight over the 24 weeks test period – average body weight decreased by 11.1kg in the low-carb group in comparison to 6.9kg in the low-glycemic group.

Not only that, there were a number of other benefits too group 1 had greater improvement in blood cholesterol levels, and in most volunteers their diabetes medications were either reduced or eliminated altogether. 


Key Point: Controlled studies have shown that the ketogenic diets can help you lose more weight than a low-fat diet.

Very Low-carb Diets and Health – Pros and Cons

The studies discussed above all suggest that following a very low-carb diet is beneficial for weight loss. However, the methodology of the diet may not suit everyone. Here is a breakdown of the potential risks and benefits:

Firstly, there have been a number of side effects reported in the science – hypoglycemia, menstrual irregularities and muscle soreness.

There have also been more serious adverse reactions reported as well, such as kidney stones and ketoacidosis – a severe form of ketosis that is common in alcoholics and untreated type 1 diabetics. It can cause abdominal pain, shortness of breath, nausea and even death.

A number of case study reports have reported death in those on long-term VLCKD diets [5, 6]. These are only rare however.

On the whole, very low-carb diets have been seen to improve health status for a number of illnesses and conditions. Studies have shown that this type of diet can improve insulin and blood glucose control, therefore being recommended for type 2 diabetics [7]. It has been shown in review studies to reduce the occurrences of seizures in 67% of epileptics [8]

Lastly, there is also some evidence to suggest that a VLCKD can decrease cardiovascular disease risk. Not only was this mentioned in #study 2 by Yancy et al [3], it has also been seen other studies as well [9].

Summary – Losing Weight with a Keto Diet

The ketogenic diet is a high-fat, very low-carbohydrate diet that allows less than 50g of carbohydrates per day, and replaces them with fats and protein maintain energy balance.

Following this type of diet will increase the number of ketones in your blood. These are organic compounds that are produced by the liver and increase in times of carb restriction. These ketones supply the body’s cells with energy as opposed to glucose – and this increases fat burning. This process is called ketosis.

Research shows that the keto diet can improve weight loss results in comparison to low-fat diets, as well as decrease fat mass –  whilst at the same time preserve lean muscle.

Very-low carb diets have also been shown to improve the symptoms of a number of metabolic illnesses such as diabetes and cardiovascular disease, as well as neural diseases such as epilepsy. There can however be side effects in some people. These include nausea, hypoglycemia and abdominal pain, as well as in rare cases, death.


  1. Bueno, NB et al. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition (2013), 110, 1178–1187
  2. Johnston, DG et al. Some hormonal influences on glucose and ketone body metabolism in normal human subjectsCiba Foundation symposium. 1982; 87: 168–91.
  3. Yancy, WS et al. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia. Annals of Int Med. 2004; 140: 769-777
  4. Westman, EC et al. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr Metab (Lond). 2008; 5: 36.
  5. Stewart, WA et al. Acute pancreatitis causing death in a child on the ketogenic diet. J Child Neurol. 2001 Sep; 16(9): 682
  6. Bank, IM et al. Sudden cardiac death in association with the ketogenic diet. Pediatr Neurol. 2008; 39: 429-431
  7. Yancy, WS et al. A low-carbohydrate, ketogenic diet to treat type 2 diabetes. Nutr Metab (Lond). 2005; 2: 34.
  8. Kinsman, SL et al. Efficacy of the Ketogenic Diet for Intractable Seizure Disorders: Review of 58 Cases. Epilepsia. 1992; 33(6): 1132-1136
  9. Hession, M et al. Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities. Obes Rev. 2009; 10(1): 36-50