Randomised Controlled Trial to Evaluate Impact of Energy Expenditure Information on the Outcome of Weight Loss During a Standardised Multicomponent Weight Management Intervention

Weight loss is important to improve overall health and reduce risk of obesity-related comorbidities such as diabetes. Numerous studies performed on individuals with predisposed genetic propensity to obesity who are deemed to be metabolically 'thrifty', require further structured intensification of caloric restriction and change in physical activity in order to achieve weight loss. Whether greater weight loss is as a result of smaller reduction in energy expenditure with calorie restriction is not known. Resting energy expenditure and 24-hour energy expenditure vary substantially between individuals. Obese individuals that lose weight experience a decrease in 24-h EE and resting energy expenditure that is lower than predicted based on changes in body composition. Most weight loss studies have found a large individual variation in the amount of weight change, and whether an individual's response to an intervention can be predicted is not clear. Measurements of 24-hour EE in response to fasting may help predict weight loss. The ECAL indirect calorimeter (ECAL) is a validated device purpose-built to provide the practitioner and patient with energy information that allows for more accurate, reliable method of establishing an obese individuals' metabolic profile. The ECAL device also measures the respiratory quotient (RQ) which is the ratio of the volume of carbon dioxide expired to that of oxygen consumed by the individual for every breath. Previous studies demonstrated variability in role of RQ in predicting weight loss, but individuals who demonstrated an RQ in the lower range (<0.72) were more likely to maintain the weight-loss achieved on a caloric restriction and avoid a weight loss rebound as compared to those with RQ in the higher range (>0.75). This suggests that RQ could prove useful in clinical practice as a prognostic marker for long-term effectiveness of low- and very-low-calorie diets used to induce weight loss. Baltimore Longitudinal Study on Aging shared a similar finding that fasting RQ or respiratory exchange ratio adjusted for age, BMI, and fat free mass was positively related to weight change. The aim of this study is to determine whether providing energy information from ECAL indirect calorimeter as an adjunct to the multicomponent weight management intervention in non-diabetic obese and severely obese individuals would help predict the response of weight loss.