Low Carbohydrate Diets and Its Mechanism of Work

Low carbohydrate diets (LCD) is a diet plan that restrict the intake of carbohydrate and replace with protein rich foods. According to researchers, low carbohydrate diet not necessarily replace the carbohydrate with protein or fat, but rather reduce the starch and sugar intake into

For people doing low carbohydrate diet management of energy intake is unnecessary, as this diet plan focus on consuming protein and fat rather than carbohydrates. Even though both carbohydrate and protein have the same amount of energy, 4 calories in a gram, carbohydrates is the cause of excess fat in the muscles as it was the main diet for people and it break down easily in the body. While proteins are complex molecules, it takes longer to digested and break down than carbohydrate. Moreover, protein usually not use for energy but to maintain and replace tissues and to function and grow. However, when body is not enough calories from other nutrients or from the fat stored, protein will be used as energy source. Hence, consumption of higher amount of protein will not be too much for the body as it is the main building block.

In low carbohydrate diet, the carbohydrate restriction lower glucose availability, and in response changes in insulin and glucagon concentrations will direct away from fat storage and maximize fat oxidation for energy, hence promoting the metabolism of adipose tissue. In addition, lower carbohydrate consumption increase β-hydroxybutyrate, which suppress appetite and satiating effect of low carbohydrate diets containing relatively high amounts of protein. On top of that, the weight loss also due to reduction of glycogen stores form liver and muscle and excreted in urine. However, recent studies show that the rapid weight loss in this diet plan will last for the first year, afterwards the level of weight loss will be slowed down (Adam-Perrot, Clifton and Brouns, 2006).

In addition, there are several other reports indicating metabolic advantage in low carbohydrate diets over short term (3–6 months). In an obese diabetic subjects, a Low cholesterol diet was associated with a significant reduction in body weight, BMI, fasting blood glucose, HbA1C and significant increase in insulin sensitivity at 6 months. Additionally, most significant weight loss in low carbohydrate diet is in range 3 to 6 months. Additionally, a short-term studies has been conducted and shows there are no negative impact on cardiovascular risk (Adam-Perrot, Clifton and Brouns, 2006).

In terms of health, low carbohydrate diet reduce the triglyceride level and effect the low density lipoprotein (LDL) as well as high density lipoprotein (HDL) cholesterol which indirectly triggered by fatty acid distribution and fat intake (Wylie-Rosett et al., 2012). In very low density lipoprotein (VLDL) there also reduction of triacylglycerol from blood (Fig.1).

Figure 1: Regulatory pathway of ketone body formation during low carbohydrate diet

On the other hand, in nutritional aspect, LCD pose a risk of nutritionally inadequate as it restrict the food choices. The restrictions reduces the overall intake of dietary fibres, vitamins, calcium, potassium, magnesium and iron.