Study of stress response to novel laboratory challenges in relation to body fat distribution in normal young adults and habituation to repeated stress challenges

Background: Perceived stress negatively affects cardiovascular functions and body fat distribution. Aims: The aim is to study whether participants with greater central fat have altered autonomic activity in response to novel laboratory stress challenges and whether they adapt less effectively to repeated stress challenges over time. Materials and Methods: Two hundred and forty-four healthy adults within the age group 20–45 years were divided into eight groups consisting of 30–31 participants in each group on the basis of sex, body mass index, and waist–hip ratio (WHR). Resting pulse rate and blood pressure were measured. All participants had to go through two stress sessions. Stress sessions were arranged according to trier social stress test. Pulse, systolic blood pressure and diastolic blood pressure (DBP), heart rate variability (root mean square of successive differences), and capillary blood glucose were measured on three consecutive occasions, -at rest, immediately after stress session 1 (day 1), and immediately after stress session 2 (day 2). Results: Among lean males and lean females, there was significant difference in blood glucose level between high WHR group and low WHR group after stress session 1 and after stress session 2. Among overweight participants, no significant difference in heart rate variability was observed between high WHR group and low WHR group after stress session 1 and after stress session 2. However, in lean participants, significant difference was observed between high WHR group and low WHR group after stress session 1 and after stress session 2. Significant difference in pulse rate and DBP was observed in lean participants between high- and low-WHR groups after stress session 1 and after stress session 2. Conclusions: Central fat among lean participants may be an indicator of the allostatic load which contributes to physical damage resulting from lack of adaptation to stress. Thus, lean participants with high WHR may be at higher risk of disease.