BackgroundThe role of specific unsaturated fatty acids (FAs) in the development of overweight/obesity remains unclear in the general population. Here, we aimed to explore the associations of different types of unsaturated FAs with overweight/obesity risk among the Chinese population.MethodsEight thousand seven hundred forty-two subjects free of overweight/obesity at entry in the China Health and Nutrition Survey (CHNS) were followed up until 2015. Dietary unsaturated FAs were assessed by 3-day 24-h recalls with a weighing method in each wave. Cox regression models were used to obtain the hazard ratios (HRs) and 95% confidence intervals (CIs) for overweight/obesity risk associated with unsaturated FAs.ResultsDuring a median follow-up of 7 years, 2,753 subjects (1,350 males and 1,403 females) developed overweight/obesity. Consuming more monounsaturated FAs (MUFAs) was associated with a lower risk of overweight/obesity (highest vs. lowest quartile: HR 0.80, 95% CI 0.67–0.96;P-trend = 0.010). Similar inverse associations were observed for plant-MUFAs (HRQ4vsQ10.83, 95% CI: 0.73–0.94;P-trend = 0.003) and animal-MUFAs (HRQ4vsQ10.77, 95% CI: 0.64–0.94;P-trend = 0.004), total dietary oleic acid (OA) (HRQ4vsQ10.66, 95% CI: 0.55–0.79;P-trend <0.001), plant-OA (HRQ4vsQ10.73, 95% CI: 0.64–0.83;P-trend <0.001) and animal-OA (HRQ4vsQ10.68, 95% CI: 0.55–0.84;P-trend <0.001). In addition, the intakes of n-3 polyunsaturated FAs (PUFAs) (HRQ4vsQ11.24, 95% CI: 1.09–1.42;P-trend = 0.017) and α-linolenic acid (ALA) (HRQ4vsQ11.22, 95% CI: 1.07–1.39;P-trend = 0.039) but not marine n-3 PUFAs were positively linked to overweight/obesity risk. Consumption of n-6 PUFAs (HRQ4vsQ11.13, 95% CI: 0.99–1.28;P-trend = 0.014) and linoleic acid (LA) (HRQ4vsQ11.11, 95% CI: 0.98–1.26;P-trend = 0.020) had marginal and positive relationships with the incidence of overweight/obesity. N-6/n-3 PUFA ratio ranging from 5.7 to 12.6 was related to higher risk of overweight/obesity.ConclusionHigher dietary intake of MUFAs was associated with lower overweight/obesity risk, which was mainly driven by dietary OA from either plant or animal sources. Intakes of ALA, n-6 PUFAs and LA were related to higher risk of overweight/obesity. These results support consuming more MUFAs for maintaining a healthy body weight among the Chinese population.