Obesity is a complex disease that greatly increases the risk of diabetes and cardiovascular disease. Non-surgical weight loss is the first line of therapy for weight loss; however, many people struggle to lose weight loss and keep it off. There are strong connections between obesity and stress. Elevated levels of the stress hormone cortisol share several clinical metabolic and cardiovascular outcomes that are also apparent with obesity. It is well known that cortisol promotes cravings for sweet fatty foods and fat accumulation around the stomach region. For these reasons cortisol may play a key role in weight loss success. No studies have critically evaluated the relationship between stress and weight in healthy obese. Whilst salivary cortisol is a common technique used to diagnose Cushings Syndrome; a condition characterized by chronically elevated cortisol levels; few studies have validated this method in obesity.
Therefore, this study aims to investigate the relationship between stress and weight in healthy sedentary lean (N=12) and obese women (N=20) by assessing salivary cortisol levels throughout the day and correlating with a range of metabolic parameters including body mass index (BMI), waist circumference, body composition, adipocyte size, stress and diabetes risk. Cortisol follows a diurnal pattern, with highest levels in morning and lowest levels in evening. Day-to-day variation in salivary cortisol has not been validated; therefore, we assessed this at various time-points over multiple days. We find that obese tend to have greater variation in morning cortisol compared to lean women, and this is associated with higher anxiety and perceived stress rather than fatness. We find BMI correlates with waist circumference, fat mass, and adipocyte size but not HbA1c or cortisol. These studies demonstrate the requirement of taking multiple samples to assess cortisol metabolism. Future studies will investigate the relationship between cortisol and non-surgical weight loss success.