Obesity surgery: should we cut the fat?

So you’ve developed type 2 diabetes and are overweight? Some experts might want you to consider surgery.

It’s a far cry from the standard prescription: blood-sugar lowering medications, diet and exercise. But that’s the advice of a panel of 48 experts, published last May in a journal called Diabetes Care. What they recommend, sooner rather than later, is bariatric surgery to shrink the size of your stomach and bypass bits of your small intestine. (Bariatric comes from the Greek word for weight.)

Surgery for diabetes may seem extreme. But for more than half of those affected, standard interventions fail to control their high blood sugar and the resultant damage to blood vessels can lead to blindness, kidney failure, heart disease and stroke. By contrast, surgery can reverse diabetes in up to 60% of patients.

The 48 experts are not rebels. They were “ voting members” at the Diabetes Surgery Summit held in London last September. Their guidelines have been endorsed by 45 international professional societies.

Besides a reversible gastric band, two non-reversible procedures are used in bariatric surgery: vertical sleeve gastrectomy and Roux-en-Y gastric bypass. The first staples off a major chunk of the stomach so you eat less; the second reroutes food from the stapled stomach to the lower part of the bowel, bypassing the duodenum so you both eat and absorb less.

The 48 experts – three-quarters of whom were not surgeons – recommend surgery should be offered to anyone whose Body Mass Index is above 30 if their blood sugar isn’t well controlled. They also call on governments and health insurers to provide subsidies.

The number of potential candidates for surgery is huge. There are currently about a million people with type 2 diabetes in Australia, and an estimated 50–60% of them are obese. If they were to receive surgery at $11,000 per operation, that’s a $2.75 billion price tag, not including dieticians, psychologists, failed operations and complications.

That’s an eye-popping number but it’s not that different to the bills for knee and hip replacements, cardiac stenting and bypass operations – procedures that often arise from obesity and diabetes. If we don’t baulk at these procedures, why should we baulk at bariatric surgery?

Well, we know why. It’s because we think “diabesity” – where diabetes is linked to obesity – is an entirely preventable condition, resulting from weak will and perhaps ‘bad parenting’.

Yet there isn’t a shred of evidence that indulgent parenting causes obesity.

Research from Joe Proietto and colleagues at the University of Melbourne has found that in obese youngsters, the hormones that regulate appetite seem to be at fault. They are rigidly set at high levels and are not brought down by dieting. This goes a long way to explaining what we all know: weight-loss diets don’t work in the long term.

People who develop diabesity later in life may also be victims of their hormones. Unpublished studies from Stephanie Amiel’s group at King’s College in London and other studies from the University of Cincinnati suggest that some young people, even before the kilos start piling on, are unusually resistant to the hormone insulin that lowers blood sugar. The pancreas responds by pumping out even more insulin; insulin, in turn, triggers fat storage.

The fascinating thing about bariatric surgery is that it seems to re-set both blood sugar levels and appetite control in a way that dieting doesn’t. Within days of surgery, well before any significant weight loss, patients suddenly experience a return to lower blood sugar levels. And there’s a sustained preference for a lower fat, less sugary diet.

Exactly how that happens is a bit of a mystery. The gastrointestinal tract secretes more than 40 hormones and is densely wired with nerve cells. These chemical and neural signals control our metabolism and appetite control. Changing its architecture changes those signals. Microbes that live in the bowel add chemical signals of their own and are also clearly affected by surgery.

A greater role for surgery does not replace interventions to help people take control of their lifestyle choices. It also doesn’t mean you let up on unhealthy food marketing to children and the availability of cheap sugar-filled soft drinks. The only weak will in the prevention of obesity is that of politicians unwilling to regulate the food industry and stare down its lobbyists.