Effect of Speed of Weight Loss on Compensatory Mechanisms Activated During Weight Reduction

Effect of Speed of Weight Loss on Compensatory Mechanisms Activated During Weight Reduction

Obesity has become a global epidemic with huge public health implications. Although clinical significant weight loss (WL) can be achieved by a combination of diet and behavioral modification, strong metabolic adaptations, with increased appetite and suppressed energy expenditure, are activated, which compromise WL maintenance and increase the risk of relapse. The aim of this project is to investigate the potential role of WL rate in modulating such responses. More specifically, the investigators want to determine if a similar WL achieved rapidly vs slowly induce the same compensatory responses to weight reduction. A secondary aim is to assess if speed of weight loss can influence motivation. A large battery of assessments will be performed before and after weight reduction including body composition, resting metabolic rate, substrate oxidation, exercise efficiency, fasting and postprandial release of several appetite-regulating hormones, subjective feelings of hunger and fullness and motivation. This project can bring large practical benefits concerning the design of weight loss programs to minimize weight relapse.

Inclusion Criteria:

• Adult (18-50 years old)
• Obese healthy volunteers (30<BMI<45 kg/m2)
• Weight stable on the last three months (<2kg), not currently dieting to lose weight and with an inactive lifestyle)

Exclusion Criteria:

• History of endocrine/cardiovascular/pulmonary/kidney disease, anaemia, gout, milk intolerance, depression or other psychological disorders, eating disorders, drug or alcohol abuse within the last two years and current medication known to affect appetite or induce weight loss. Those with a planned surgery during the study period or participating in another research study will also not be accepted to take part in this study