More sugar? No, thank you! The elusive nature of low carbohydrate diets

In the past decades, dietary guidelines focused on reducing saturated fat as the primary strategy for cardiovascular disease prevention, neglecting the many other potential effects of diet on health, in particular the harmful effects of sugar. A greater intake of soft drinks (sugar-sweetened beverages), for example, is associated with a 44% increased prevalence of metabolic syndrome, a higher risk of obesity, and a 26% increased risk of developing diabetes mellitus. Carbohydrates comprise around 55% of the typical western diet, ranging from 200 to 350 g/day in relation to a person’s overall caloric intake. For long-term weight gain, food rich in refined grains, starches, and sugar appear to be major culprits. Low-carbohydrate diets restrict daily carbohydrates between 20 and 50 g, as in clinical ketogenic diets. The results of controlled trials show that people on ketogenic diets (a diet with no more than 50 g carbohydrates/day) tend to lose more weight than people on low-fat diets. Moreover, there is no good evidence for recommending low-fat diets, as low-carbohydrate diets lead to significantly greater weight loss (1.15 kg) than did low-fat interventions. However, the magnitude of such a benefit is small. As the quality of ingested carbohydrates seems more important than the quantity for health outcomes, people with metabolic disorders should avoid or substantially reduce low-fiber, rapidly digested, refined grains, starches, and added sugars. So, the consumption of the right carbohydrates (high-fiber, slowly digested, and whole grains), in a moderately lower amount (between 40 and 50% of daily energy content), is compatible with a state of good health and may represent a scientifically-based and palatable choice for people with metabolic disorders.