Nutrition Meets Food Science

Low Carbohydrate Diets for Weight Loss

There is a rising prevalence of obesity in recent years. While causes of obesity are many including genetic factor, sedentary lifestyle, imprudent dietary pattern, urbanisation etc, cure is only one—lifestyle modification.  The main pillars of “life style modification” are diet and exercise.

Nutrition Meets Food Science - Keto Diet

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Going on a “diet” has become a fad now. Actually, the word “diet” means a way of life. But instead of using sensible eating patterns as way of life, FAD diets have seen a surge. One such FAD diet is low carbohydrate diet.

Low carbohydrate diet is a diet where the calories coming from carbohydrates are about 5-10%. In normal Indian diet about 70%of calories come from carbohydrate. Hence you can see that there is drastic reduction in calories from carbohydrate. When diet is restricted in carbohydrates, body lacks energy. In such circumstances body is forced to use fat (body fat) as a source of energy. Some of the body organs like brain can exclusively utilise only glucose. The other nutrient it can use is ketone. Ketone in  body is formed when body fat breaks down in absence of carbohydrates. Hence low carb diets are also called as ketogenic diets. Presence of ketones is the most reliable indicator of body fat mobilisation and hence these diets are very popular. These diets also suppress appetite. The mechanism of this is as follows: when carbohydrates are consumed, they are readily converted to glucose and in the response, body releases insulin. Insulin inhibits production of satiety neurotransmitters (fullness chemicals) in the brain. Hence consuming carbohydrate rich meals leaves person craving for more food. When carbohydrates are restricted, satiety neurotransmitters are secreted, and hence person feels full fast. This leads to decreased intake and hence weight loss.

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As ketosis also happens in starvation, ketogenic diets are also compared to starvation. The major difference between starvation and ketogenic diet is, while in starvation all nutrients are scarcely available, leading to loss of fat and muscle, in low carb diet muscle mass is preserved by dietary protein which is given in a good amount to prevent muscle loss. So low carb diets prevent muscle loss and enhance fat loss. Due to all these reasons, low carb diets become attractive option for those who want to lose weight very fast.

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The hind sight of this is that these diets are very difficult to follow and sustain over a long period of time, especially in carb rich country like India. Research from recent studies published in leading journal like Lancet has shown that when diets are lower than or higher than 50% of carbohydrates there is increased mortality (or death). Also, these diets have very little fruit and vegetable in them. Diets low in fruit and vegetable predisposes a person to risk of constipation in early stages and also colon cancer later. 

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Whatever the diet fads are, it’s important to maintain good proportions of all nutrients in the diet and not cut off any part of pyramid. One has to remember that weight loss is defined as loss of 5-10% initial body weight which is maintained over one year. Instead of following any drastic measures like this sensible low calorie intake accompanied by physical activity is a sound way of losing and maintaining lost body weight.

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Shilpa Joshi

Mumbai Diet and Health Center
National Vice President, Indian Dietetic Association
Hon. Secretary All India Association for Advancing Research in Obesity

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