Approach to the patient who is obese

Obesity is condition surrounded in stigma so it is very important to understand the definitions. It is reductionist to state that obesity is caused by excessive energy intake and/or inadequate energy expenditure as there are a number of complex interacting metabolic processes.

Leptin is a hormone secreted by adipose when substrate is plentiful and acts as a satiety signal to inhibit appetite and increase substrate utilisation and acts through the hypothalamus. People who are obese may be an a state of relative leptin resistance and do not respond adequately to an increased leptin level.

This is a bit trickier so hopefully this explanation will help make sense. The question is describing Cushing's syndrome, which is the clinical manifestation of pathological hypercortisolism. This can be caused by endogenous or exogenous corticosteroids. An example of pathological endogenous corticosteroids would be a adrenocorticotropic hormone secreting pituitary adenoma. However, the most common cause of Cushing's syndrome is exogenous corticosteroids, therefore is prednisolone. Hypothyroidism, sodium valproate and clozapine can all cause weight gain, but will not result in Cushing's syndrome.

Sleep apnoea is often, but not always, associated with obesity. Due to the increased tissue mass, when the muscles relax during sleep this can lead to a partial or complete airway obstruction, this can cause apnoeic periods or ineffective ventilation. This will result in individuals not feeling refreshed after sleep and/or waking multiple times a night. Poor sleep is linked to an increased appetite and thus sets up a vicious cycle

Obesity results in higher levels of fat so the body must produce more bile salts, this can overcome the ability of the gall bladder. In addition there is an increased association with gallbladder stones which results in obstructive jaundice. Remember that gall bladder issues can be incredibly painful so ensure patients receive adequate analgesia for their pain!

Obesity and cancer has a well documented associated and obesity is now an acknowledged risk factor for: breast (post menopausal), endometrial, colon, kidney and oesophagus cancers. This must be approached in a sensitive manner as it is not as simple as "eat less and move more".

Many anti-depressants can result in weight gain, with mirtazapine notorious for causing weight gain. Bupropion is an anti-depressant that is not associated with weight gain as a side effect. Remember the BNF is always a great resource to look at!

Anti-psychotics inhibit the H1 and 5HT receptors which results in an increase in appetite. In the central nervous system, serotonin (5HT) suppresses appetite (so its inhibition would stop this suppression). Olanzapine and clozapine are well known to result in weight gain.

The hypothalamus is the centre processing unit which receives input from hormones, peripheral neural input and the cerebral cortex and is responsible for controlling appetite. This is proven in cases of damage to the hypothalamus that result in poor appetite control