Introduction: Diet and lifestyle modification is commonly used in constipation management. As there is a dearth of studies on this topic in Malaysia, we aim to elucidate the relations between stool patterns, dietary intake and physical activity levels among adults with functional constipation. Methods: From a database collected via surveys at public events, a convenience sample of 100 adults diagnosed with Rome II-defined functional constipation was enrolled in this cross-sectional study. After severity assessment using the Chinese Constipation Questionnaire, subjects completed 2-week bowel movement diaries to determine stool frequency, consistency and output. Dietary intake and physical activity levels were assessed twice using three-day 24-hour diet recalls and International Physical Activity Questionnaire, respectively. Ninety subjects who completed the study were included in the analysis. Results: Mean weekly stool frequency was 3.9±1.9 times, consistency score was 2.6±0.6 (range 1.0-4.0), output was 11.0±6.3 balls (40 mm diameter) and severity score was 10.3±3.3 (range 5.0-22.0). Mean daily dietary intakes were: energy 1,719±427kcal, dietary fibre 15.0±4.9g and fluid 2.5±0.8L. The majority of subjects were physically inactive. Stool frequency and output were positively associated with dietary fibre (rs=0.278, P<0.01; rs=0.226, P<0.05) and fluid intake (rs=0.257, P<0.05; OR=3.571, 95% CI [1.202-10.609]). Constipation severity was associated with higher physical activity levels (OR=2.467, 95% CI [1.054-5.777]). Conclusion: Insufficient intake of dietary fibre and fluid are associated with aggravated constipation symptoms. Further studies are necessary to confirm usefulness of dietary intervention in treatment of constipation as dietary factors alone may not influence overall severity and stool consistency, an integral element of constipation.