Diets that drastically reduce carbohydrate intake, such as sugar restriction, are harmful to the body in the long term.

Researchers at a university in Melbourne, Australia, have published a paper stating that diets that reduce carbohydrate intake, such as the 'carb-restricted diet' that reduces carbohydrate intake, and the 'ketogenic diet' that replaces calories from carbohydrates with lipids, are bad for the body in the long term.

Association of low carbohydrate diet score with the risk of type 2 diabetes in an Australian population: A longitudinal study - ScienceDirect

The research was conducted in collaboration with Monash University, RMIT University and others in Melbourne, Australia.

Type 2 diabetes, known as a lifestyle-related disease, is thought to be preventable and ameliorative by carbohydrate restriction, but the research team believed that a diet for preventing type 2 diabetes may be different from a healthy diet, and thoroughly investigated the health data of Melbourne residents recruited between 1990 and 1994. This cohort was followed up in either 1995-1998 or 2003-2007.

Participants were given a 'low-carb score' based on the relative amount of carbohydrates they ate compared to fat and protein.

The survey found that those in the top 20% of scores got about 38% of their energy from carbohydrates, while those in the bottom 20% got about 55% of their energy from carbohydrates.

They found that people who ate less carbohydrates had a 20% higher risk of developing type 2 diabetes over the course of the study compared with those who ate more carbohydrates, with most of the risk coming from a higher BMI .

These results suggest that a low-carbohydrate diet may lead to weight gain in the long term and increase the risk of developing metabolic diseases.

People who reported eating the lowest amount of carbohydrates in the study tended to eat less fiber and more protein and fat than those who reported eating the highest amount of carbohydrates.

The researchers say this may be mainly due to the fat content of the diet, especially high unsaturated fats, and that instead of focusing only on carbohydrates, people also need to take into account what else they are eating.