Materials and Methods: In the present cross-sectional study, the subjects (n = 176) were asked to eat their lunch at work on the test day. The postprandial concentration of PYY3-36 was measured 1.5 to 2 hours after the consumption of lunch meal.

Results: The subjects within the age range of 25 to 39 and those with ages less than 25 (P = 0.005) indicated the highest and the lowest levels of PYY3-36, respectively. Postprandial PYY3-36 had a direct significant association with fat content at lunch (P = 0.049) and had an inverse association with cholesterol (P = 0.001), docosahexaenoic acid (DHA) (P = 0.040) and eicosapentaenoic acid (EPA) (P = 0.022). Moreover, polyunsaturated fatty acids (PUFAs) and linoleic acid at lunch indicated a significant positive correlation with PYY3-36 (r = 0.182, P = 0.016 for both). Furthermore, a significant negative correlation was detected between energy intake at dinner and post-lunch PYY3-36 (r = -0.216, P = 0.004). Protein (OR [odds ratio] = 0.390, 95% CI: 0.160-0.950) and fat intake (OR = 2.697, 95%CI: 1.103-6.594) at lunch, energy intake at dinner (OR = 0.298, 95% CI: 0.127-0.702), and energy spent to perform physical activities after lunch (OR = 0.411, 95% CI: 0.182-0.929) significantly predicted the serum concentration of post-lunch PYY3-36. No significant association was found between PYY3-36 and glycemic index and load.

Conclusions: There was a significant association between dietary intakes at lunch meal and post-lunch serum concentration of PYY3-36. Further large-scale cross-sectional researches and randomized controlled trials are needed to confirm the mentioned results.