Popular weight loss diet increases type 2 diabetes risk by 20%
A diet low in carbs and high in fat, which has gained popularity as a way of shedding weight, can increase the risk of type 2 diabetes by 20%, according to a new study. The research team behind the study says their findings highlight the need to eat a balanced diet.
Worldwide, in developed countries, the prevalence of type 2 diabetes (T2D) continues to rise despite the implementation of public health measures. The link between eating a poor-quality diet and T2D risk has been known for a while, but what effect does eating a low-carb, high-fat diet have on that risk? That’s the question researchers from Monash and RMIT Universities in Melbourne sought to answer as part of a large, long-term study.
“We know that high-carbohydrate diets that are highly processed, low in fiber, and rich in refined sugars can lead to weight gain,” said Professor Barbora De Courten from the Department of Medicine at Monash and the School of Health and Biomedical Sciences at RMIT and the study’s co-corresponding author. “Furthermore, the highly refined carbohydrates can lead to increased insulin secretion and insulin resistance, leading to type 2 diabetes.
“But studies to date have only focused on examining low carbohydrate for managing and/or remission of type 2 diabetes. Instead, this study reveals that a low carbohydrate diet intake might increase the long-term risk of type 2 diabetes through obesity, potentially through increased eating of fats and foods low in fiber.”
Existing research into the association between eating a low-carb diet and the incidence of diabetes is conflicting, and most of it has been carried out on European and Asian populations. So, the researchers obtained data from the Melbourne Collaborative Cohort Study (MCCS) for 39,185 adults aged 40 to 69. Participants were recruited into the MCCS between 1990 and 1994, then followed up for up to 17 years.
From the data, the researchers analyzed the association between a low-carbohydrate diet (LCD) score and the incidence of T2D later in life. LCD score was calculated at baseline as the percentage of energy participants got from the carbohydrates, fats, and proteins they ate. A high LCD score represented a low-carb, high-protein and high-fat dietary pattern.
The researchers found that LCD was positively associated with diabetes risk. Specifically, participants who obtained 38% of their energy from carbohydrates had a 20% greater risk of developing T2D than those who obtained 55% of their energy from carbs. They also found that the association between LCD score and T2D was largely explained by obesity, with body mass index (BMI) mediating 76% of the association.
“In this study, we have shown that low-carbohydrate diet score may increase the long-term risk of T2D and this relationship was mediated by obesity,” the researchers said. “This finding might be mainly due to the high fat content of the diet (specially unsaturated fat), thus implying reducing one type of diet only may not be a guarantee, rather the replacement or use of other dietary items also needs to be considered.”
Based on their findings, the researchers reinforced dietary advice about eating a balanced diet and suggested that the Mediterranean diet may be optimal to prevent T2D.
One of the study’s limitations is that the data they used is 16 years old, and the dietary data was self-reported. Nonetheless, the researchers say that the data was still valuable. These limitations must be viewed alongside the study’s strengths: a large cohort followed up over a long period, with many possible confounders being adjusted for. Further studies, including clinical trials looking at the effects of a low carbohydrate diet with different sources of carbs on T2D, are needed.
The study was published in the journal Diabetes & Metabolic Syndrome: Clinical Research & Reviews.
