The gut-brain axis plays a crucial role in appetite control. Circulating gut hormones send signals to the brain to inform whether we feel hungry or full. Ghrelin, our hunger hormone, is secreted by the stomach just before meal times to signal that we feel hungry. After meals, satiety hormones such as GLP-1 and PYY are secreted by the intestine to signal to the brain that we feel full. In people with obesity, some of these gut hormone responses are impaired and may contribute to their obesity.
The problem with losing weight
When we attempt to lose weight through dieting, our gut-hormone response leads to increases in ghrelin and decreases in our satiety hormones. This is the body’s way of telling the brain that we have lost weight and we must fight to regain the calories lost. Furthermore, when we lose weight, our basal metabolic rate, the energy required to keep our basic metabolic processes ticking, is lower, that is we need to eat less calories to maintain the new body weight. These lower energy requirements, together with gut hormone response, are some of reasons to explain the challenges of weight loss maintenance.
Combining lifestyle change and medication
Lifestyle and dietary changes are the cornerstone of any dietary loss programme, but diet alone may not be enough when trying to maintain weight loss long-term. New pharmacotherapies are now available for the treatment of obesity. Medication can mimic the action of the satiety hormone GLP-1 and works by decreasing appetite through its action on the brain. Clinical trial data show that obese patients can achieve a mean weight loss of 8% in one year, although patients with an early response can achieve more. For patients with prediabetes, medication can reduce the incidence of developing type 2 diabetes over 3 years. These gut-hormone therapies are promising and effective treatments in the fight against obesity and related co-morbidities.