Dietary n-6 PUFA, carbohydrate:protein ratio and change in body weight and waist circumference: a follow-up study.

Objective: To investigate the association between the intake of n-6 PUFA and subsequent change in body weight and waist circumference at different levels of the carbohydrate:protein ratio.
Design: Follow-up study with anthropometric measurements at recruitment and on average 5·3 years later. Dietary intake was determined at recruitment by using an FFQ that was designed for the study and validated. We applied linear regression models with 5-year change in weight or waist circumference as outcome and including a two-way interaction term between n-6 PUFA and carbohydrate intakes, lower-order terms, protein intake, long-chain n-3 PUFA intake and other potential confounders. Due to adjustment for intake of protein, levels of carbohydrate indirectly reflect levels of the carbohydrate:protein ratio.
Setting: Diet, Cancer and Health follow-up study, Denmark.
Subjects: Women and men (n 29 152) aged 55 years.
Results: For a high intake of n-6 PUFA (6·9 % of energy) v. a low intake of n-6 PUFA (3·4 % of energy), the difference in 5-year weight change was -189·7 g (95 % CI -636·8, 257·4 g) at a low carbohydrate:protein ratio and -86·7 g (95 % CI -502·9, 329·6 g) at a high carbohydrate:protein ratio; the differences in 5-year waist circumference change were 0·26 cm (95 % CI -0·47, 0·98 cm) and -0·52 cm (95 % CI -1·19, 0·15 cm), respectively. Inclusion of the dietary glycaemic index did not change the results.
Conclusions: No consistent associations between the intake of n-6 PUFA and change in body weight or waist circumference at different levels of the carbohydrate:protein ratio were observed.