The Ketogenic Diet – What is a Keto diet?

Keto diet is a type of low carbohydrate diet. Unlike other low carbohydrate diets this depends on high fat intake and not protein intake to supply calories. The fat is converted to ketone bodies in liver when glucose is low and ketones are burnt to give calories. The protein intake is restricted because it can be converted to glucose during starvation preventing ketosis. Typically keto diet consists of consuming 55% to 60% of daily calories from fat, 30% to 35% from protein and 5% to 10% from carbohydrates.  It does not differentiate between saturated and unsaturated fat and freely allows saturated fat from butter, oils etc… to meet calorie requirements.  Because carbohydrate intake is kept very low, intake of vegetables and fruits are limited.

Keto diet has been associated with significant weight loss starting as early as 2 weeks. In clinical studies its shown to reduce weight by 7.8kgs over a mean duration of 35 weeks (compared to 5.9 kg with low fat diet). The effect is sustained even up to 2 years but seems to be less during longer follow-up. Keto diets are associated with better sugar and blood pressure control.

 

The concerns with Ketogenic Diet are many. The first and foremost one is sustainability. Almost all diets fail because it’s difficult to sustain the diet and benefits. Keto diet is difficult to follow in long run especially the high fat content which is not palatable. Because of the very low carbohydrate intake there’s major restriction in eating vegetables and fruits and other plant based products. This causes micronutrient deficiencies especially vitamins. It also means low fiber content and constipation.  The high fat content is associated with increase in LDL cholesterol level in blood which has been shown earlier to be bad for the heart. Physiologically when we get calories from ketones there can be acidosis. It can lead to kidney stones.  During the initial phase of Ketogenic Diet when the body is not used to ketosis there can be flu like illness with dizziness, vomiting, headache and fatigue.

There is no long term data on the effectiveness and safety of keto diet. Evidence for effectiveness of weight loss induced by keto diets in reducing cardiovascular disease and mortality is also not available, whereas there are other diets like Mediterranean which have clinical evidence for reducing heart disease.

To summarise Ketogenic Diet is effective in reducing weight numerically more than low fat diet.  But whether this can be sustained is not known. It is not physiological and hence the long term consequences have to be studied in large population before clinical recommendation can be made. But it is becoming clearer that too much of carbohydrates especially the refined type is not good for health. Hence what can be recommended is definitely lower calorie intake to lose weight with reduction in refined carbohydrates. Moderation in consumption of fat is essential but we still have not heard the last word. All fats are not the same and may not necessarily be as evil as portrayed.

Dr. K. Abirami, M.B.B.S., M.D., D.M.(Nephro), M.R.C.P.(London)
Consultant Nephrologist, Kauvery Hospital Salem

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