Is a ketogenic diet effective for weight loss? The answer depends on
whether it achieves a reduction in total kilojoule intake or not.
The difference between a strict ketogenic diet and diets that are described as low-carb is that ketogenic diets specifically aim to achieve elevated blood levels of ketone bodies which are chemicals produced as a consequence of your body burning fat. Hence general low-carb diets are not as high in fat as classical ketogenic diets.
Research on the use of classical ketogenic diets for weight loss is limited. But there are many studies that compare lower-carb diets to other approaches.
These show that aiming for a carbohydrate restriction of 20-30 grams a day, without setting a daily kilojoule target, leads to 2-4 kilograms greater weight loss compared to a low kilojoule diet, in studies up to six months.
In longer studies with follow-up between one to five years there is no difference in weight loss. A review of weight loss diets with a moderate carbohydrate restriction (45% or less of total energy intake) compared to low fat diets (under 30% fat) found they were equally effective in reducing body weight in studies from six months to two years.
What is a ketogenic diet?
A classical ketogenic diet follows a strict ratio for total grams of fat to combined grams of carbohydrate and protein and typically has 80-90% of total kilojoules coming from fat, which is very high fat. Carbohydrate intake varies from 20 to 50 grams a day, or 5-10% of total energy, while protein intakes are moderate.The difference between a strict ketogenic diet and diets that are described as low-carb is that ketogenic diets specifically aim to achieve elevated blood levels of ketone bodies which are chemicals produced as a consequence of your body burning fat. Hence general low-carb diets are not as high in fat as classical ketogenic diets.
Research on the use of classical ketogenic diets for weight loss is limited. But there are many studies that compare lower-carb diets to other approaches.
These show that aiming for a carbohydrate restriction of 20-30 grams a day, without setting a daily kilojoule target, leads to 2-4 kilograms greater weight loss compared to a low kilojoule diet, in studies up to six months.
In longer studies with follow-up between one to five years there is no difference in weight loss. A review of weight loss diets with a moderate carbohydrate restriction (45% or less of total energy intake) compared to low fat diets (under 30% fat) found they were equally effective in reducing body weight in studies from six months to two years.