As I have the privilege of reviewing many of the patients who undergo bariatric surgery locally (either laparoscopic adjustable gastric band insertion or vertical banded gastroplasty), I was invited to speak to some of the local medicos last week on the preparation of patients for these surgical procedures.
It’s not intuitive that obesity is a problem which warrants drastic intervention. It probably needs to be reiterated that the following medical problems, which no-one really wants to suffer from, are associated with obesity, and can be a major cause of suffering in our community, as well as an increasing burden on our health-care infrastructure:
- coronary artery disease
- insulin resistance and type two diabetes
- cancer (endometrial, breast and colon)
- hypertension
- dyslipidaemia
- stroke
- liver and gall bladder diseae
- obstructive sleep apnoea and respiratory disorders
- osteoarthritis
- gynaecological problems (infertility, polycystic ovarian syndrome, menstrual irregularity)
- pseudotumour cerebri
One might also wonder what all of the fuss is about. How much of a problem is this, really? I think the accompanying graph speaks for itself. (The measurement tool that we most commonly use to assess weight / obesity is the body mass index. While this tool may be, to some extent, flawed it is pretty standard. BMI over 30 defines obesity, with BMI over 40 being labelled 'morbidly obese'. It is the tool used in collection of the data that go into compiling a graph such as this).
My professional exposure to people who struggle with obesity, and my reading around the topic, has caused me to become less and less optimistic that lasting control of weight problems can be achieved with non-surgical measures (ie diet and exercise). Professor Joe Proietto, from Melbourne, spoke at the recent World Congress of Internal Medicine in Melbourne (I wasn’t there but got the DVD!) and at the Australasian Sleep Association meeting last year. Wow, if you want to hear someone who presents a scientific basis for the failure of non-surgical weight loss and the inevitability of continued increase of the obesity epidemic in our society, then Joe is the man!
He explained that the hypothalamus, the part of the brain where appetite is ‘controlled’, seems to be programmed to hunt for food. There is only one hormone (chemical messenger) which we know of which circulates in the blood stream and is designed to stimulate appetite. It is called Ghrelin, and is secreted mainly from cells in the stomach. There is a number (around nine) of hormones that suppress appetite. The two we probably know most about are Leptin (secreted by adiopose tissue) and cholecystokinin (made and secreted in the small bowel in response to ingestion of food). Prof Joe P has convincing experimental data that demonstrate how prolonged low-calorie diet is accompanied by weight loss (no surprises there) and a reduction in secretion of leptin and CCK (ie less suppression of appetite). At the end of a prolonged period of low calorie diet, experimental subjects have their appetites unleashed and choose to eat high protein and high fat foods. In real life, this is called “Yo-yo dieting”. Seems it’s not just a matter of willpower.
Current thinking is that bariatric surgery impacts on the secretion of the above hormones, and others involved in suppression of appetite, in ways that are sustained. This facilitates long term dietary modification. It also contributes to the rapid resolution of complications of obesity, and in particular diabetes, following bariatric surgery. To my disappointment a recent review article in Nutrition journal found no good studies to date testing this hypothesis.
Bariatric surgery certainly is, however, the only intervention which regularly results in sustained weight loss. I used to be hesitant to refer patients for these procedures. Now it is often an issue discussed at the initial consultation.
Next post: What are the indications for bariatric surgery? What are the risks? What does a pre-operative evaluation entail?
Andrew
No comments:
Post a Comment