Evidence suggests that low carbohydrate eating patterns are effective for rapid weight loss 1, however, little is known about their long-term effects on the risk of chronic diseases. We assessed the association of a low carbohydrate diet score (LCD) with the incidence of type 2 diabetes using Melbourne Collaborative Cohort Study (MCCS) data. Between 1990 and 1994, the MCCS recruited 41,513 people aged 40 to 69 years. The first and second follow-ups were conducted in 1994-1998 and 2003-2007, respectively2. We analysed data from 39,185 participants. LCD at baseline was calculated as the percentage of energy from carbohydrate, fat, and protein. The higher the score the less carbohydrate contributed to energy intake. The association of LCD quintiles with the incidence of diabetes was assessed using modified Poisson regression, adjusted for lifestyle, obesity, socioeconomic and other confounders. LCD was positively associated with diabetes risk. Higher LCD score (p for trend = 0.001) was associated with increased risk of type 2 diabetes. Quintile 5 (38% energy from carbohydrates) versus quintile 1 (55% energy from carbohydrates) showed a 20% increased diabetes risk (incidence risk ratio (IRR) = 1.20 (95% CI: 1.05-1.37)). A further adjustment for BMI and WHR eliminated the association. Mediation analysis demonstrated that BMI attributed 76% of the LCD & diabetes association. Consuming a low carbohydrate diet, reflected as a high LCD score, may increase the risk of type 2 diabetes which is largely explained by obesity. Results imply the need for further studies, including clinical trials investigating the effects of a low carbohydrate diet in type 2 diabetes.

We prospectively examined the association between low-carbohydrate diet (LCD) score and incidence of type 2 diabetes (T2D) in Japanese adults using Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) data. A total of 19 084 (7052 men and 12 032 women) Japanese non-diabetic participants aged 40–79 years, who enrolled in the JACC study between 1988 and 1990, were included in our analysis. Dietary intake was evaluated using a validated food-frequency questionnaire. The overall, animal and vegetable LCD scores were calculated by dividing the study participants into eleven categories based on the percentages of energy from carbohydrates, protein and fat. The incidence of T2D was assessed using a self-administered questionnaire. We used multivariable logistic regression analysis to estimate the odds ratios (ORs) and 95 % confidence intervals (CIs) of incident T2D across the quintile of each LCD score, with adjustment for potential confounders. During the 5-year study period, 490 adults (247 men and 243 women) developed T2D. The multivariable-adjusted OR of incident T2D for the highest v. lowest quintiles of overall and animal LCD scores, respectively, were 0·64 (95 % CI 0·42, 0·99) and 0·83 (95 % CI 0·55, 1·27) for men, 0·78 (95 % CI 0·51, 1·18) and 0·84 (95 % CI 0·57, 1·24) for women. The vegetable LCD score was associated with a lower risk of T2D in men (OR 0·51; 95 % CI 0·33, 0·77). Our results suggest that diets lower in carbohydrates and higher in fat and protein are unlikely to higher the T2D risk among Japanese individuals.

Epidemiological studies on the association between the low carbohydrate diet (LCD) score and CVD risk factors have limited and inconsistent results. Data are from the baseline survey of Community-based Cohort Study on Nervous System Diseases. A total of 4609 adults aged ≥ 18 years were included in the study. Dietary data were assessed using a validated semi-quantitative FFQ. Multivariable logistic regression analyses were used to estimate relationships of three LCD scores with low HDL-cholesterol, high LDL-cholesterol, hypercholesterolaemia, hypertriacylglycerolaemia, impaired fasting glucose (IFG), high blood pressure and hyperuricaemia after adjusting for potential confounders. A higher LCD score was negatively associated with low HDL-cholesterol (OR: 0·65 (95 % CI 0·50, 0·83), P = 0·0001) and IFG (OR: 0·65 (95 % CI 0·51, 0·81), P = 0·001) after the final adjustment. However, there are sex differences in this result. Males in the highest quintile of the animal-based or plant-based LCD scores showed a decreased risk of low HDL-cholesterol, and females in the highest quintile of the animal-based or plant-based LCD scores showed a decreased risk of IFG than those in the lowest quintile of the LCD scores. These results suggest that sex differences should be considered when using LCD to treat dyslipidaemia and reduce fasting blood glucose.