Testing the Gravitostat in Humans: the Impact of a Weighted Vest in Patients Post Bariatric Surgery on Fat-free Mass Retention and Weight Loss

Testing the Gravitostat in Humans: the Impact of a Weighted Vest in Patients Post Bariatric Surgery on Fat-free Mass Retention and Weight Loss

Testing the Gravitostat in Humans: the Impact of a Weighted Vest in Patients Post Bariatric Surgery on Fat-free Mass Retention and Weight Loss

The mechanisms regulating fat mass homeostasis are incompletely understood although recent animal and human trials would suggest that there is a leptin independent regulatory pathway which may play a role in weight control and maintenance. Although evidence would suggest that external loading in patients with obesity may promote body weight loss, this has not been explored in patients following bariatric surgery. The aim of this study is to investigate the mechanisms regulating weight loss and the potential role of the 'gravitostat' in fat free mass retention in patients following bariatric surgery.

The aim of the study is to investigate the mechanisms that regulate weight loss, particularly following bariatric surgery. Previous animal studies have suggested that there is an underlying regulatory process controlled by 'the gravitostat' which is an evolutionary adaptation responsible for weight control and maintenance. Studies exploring this concept in rodent models have suggested that artificially increasing the animal's weight with the implantation of weighted capsules results in greater weight loss in mice with obesity but does not affect those of normal weight. We will use weighted vests in patients following surgery to replicate this increased mechanical loading to determine whether a similar process occurs in humans. This will improve our understanding of the underlying processes regulating weight in patients with obesity and following bariatric surgery.

Following bariatric surgery (RYGB or SG) patients will be asked to wear a weighted vest for a minimum of 8 hours daily and during physical exercise for three months postoperatively. Weight will be incrementally added on a weekly basis to maintain the baseline weight as patients lose weight following surgery up to a maximum of 15%.

Patients will wear a weighted vest following bariatric surgery with weight increased incrementally to maintain baseline weight. This vest will be worn for a minimum of 8 hours a day for three months postoperatively.

Inclusion Criteria: Undergoing bariatric surgery- Roux en Y gastric bypass or sleeve gastrectomy Age 18-60 BMI >30kg/m2 Reporting regular physical exercise (>3 days/week) Willingness to comply with the study protocol Exclusion Criteria: Sedentary lifestyle Chronic pain that is constant and impairs the quality of life such as severe back, hip or knee pain Reduced mobility requiring the use of a mobility aid Undergoing revisional surgery Concerns from the investigator that the participant will be unable to fully comply with the study protocol