BACKGROUND: Many studies have reported alteration in autonomic activity in obesity. However, there is paucity of literature comparing autonomic reactivity using different guidelines of obesity. As Indian guidelines were revised recently and WHO states that countries should use all categories of BMI for reporting purposes, it is prudent to compare physiological state in different categories of BMI.
OBJECTIVE: The aim of the present study was to compare the autonomic alteration in young adults using revised Indian and WHO guidelines for obesity.
METHODS: A battery of autonomic tests (Valsalva Manoeuvre (VM), Deep Breathing Test (DBT), Lying to Standing Test (LST) and Hand Grip isometric exercise Test (HGT) was conducted on 34 overweight and obese and 30 normal weight volunteers categorised using revised Indian guidelines of body mass index. Same participants were regrouped and analysed using WHO guidelines of BMI and waist hip ratio (WHR).
RESULTS: For analysis, participants were grouped into 3 categories of normal, overweight and obese using revised Indian guidelines for obesity. Same participants were regrouped according to WHO guidelines. E:I ratio during DBT, 30:15 ratio during LST, Valsalva ratio during VM and increase in DBP during HGT were compared in different subgroups. There was no difference in sympathetic and parasympathetic activities in participants classified according to revised Indian guidelines. In participants classified using WHO criteria, sympathetic reactivity in overweight subjects was significantly less as compared to normal subjects (p<0.05).
CONCLUSIONS: Autonomic alterations might be more related to body fat percent rather than BMI. Indian guidelines are based on the observation that Asian population has more adipose tissue in WHO range of BMI. As the guidelines of BMI are applicable to all age groups and do not consider physical activity profile, they might still not be a good predictor of body fat.