LAUSR

Abstract Background China has experienced an unprecedented rapid modernisation, major changes in diet and physical activity behaviours, and a rapid increase in prevalence of obesity. Although prevailing weight-loss guidelines recommend a fat-restricted and calorie-restricted diet, the associations between fat intake and risk of obesity have been inconsistent from epidemiological and clinical-trial evidence. We aimed to examine the influence of dietary fat on bodyweight and the risk of overweight and obesity among Chinese adults over time. Methods In this prospective cohort study, we obtained data about 22 677 people aged 20–60 years old (n=10704 men, n=11 973 women) from the China Health and Nutrition Survey (CHNS), covering 15 Chinese provinces from 1991 to 2015. We collected detailed dietary data by using three 24-h recalls in combination with the weighing of foods and condiments in household inventories. We examined the associations between fat intake, bodyweight, and the risk of overweight and obesity using time-series random-effects regression or logit models for panel data, stratified by sex. Findings During the 25-year study period, average fat intake, energy from fat, and high-fat diets (defined as >30% energy from fat) increased in men and women. In 1991, women had a fat intake of 62·5 g per day and 22·8% energy from fat, and 23·9% of women had high-fat diets; in 2015, they had an intake of 73·6 g per day and 36·3% energy from fat, and 69·8% had high-fat diets. In 1991, men had a fat intake of 69·8 g per day and 22·2% energy from fat, and 20·2% of men had high-fat diets; in 2015, they had an intake of 83·8 g per day and 35·5% energy from fat, and 66·8% had high-fat diets. During the same period the prevalence of overweight and obesity (defined as body-mass index [BMI] ≥25 kg/m2) increased from 14·6% to 35·0% among women and from 9·7% to 44·1% among men. When controlling for total energy intake, physical activities, and other variables of socioeconomic status, fat intake, energy from fat, and high-fat diets were significantly associated with bodyweight, BMI, and the risk of overweight and obesity in both sexes. Interpretation High fat intake, high-fat diets, and high energy from fat were significantly associated with bodyweight, BMI, and the risk of overweight and obesity. These results could serve as basis for dietary intervention guidelines and could be used for public health recommendations. This study breaks new ground by exploring 25-year trends in high-fat diets and their role in bodyweight and obesity risk among Chinese adults. These findings could have substantial effects on policies and interventions related to overweight and obesity. Funding National Institutes of Health ( R01-HD30880, P2C-HD050924 ), and the NIH Fogarty grant ( D43 TW009077 ).