Gastric bands are as useful as a plaster on a severed artery

I sat next to a nice chap called Ken at an obesity conference dinner in 2009. Ken had been one of the speakers that day, sharing the fact that he'd had bariatric surgery and telling the audience all good things about the procedure, glossing over the complications and weight regain in his enthusiasm. What I didn't know was that Ken worked for Gravitas, "the nationwide partnership of bariatric surgeons and clinicians". This wasn't a human interest story on the agenda; bariatric surgery is big business – morbidly big business.

On Friday, Nice issued some revised guidelines. Nice stands for the National Institute for Health and Care Excellence. It describes itself as follows: "We provide independent, authoritative and evidence-based guidance on the most effective ways to prevent, diagnose and treat disease and ill health."

There were two parts to the Nice announcement. The largely ignored recommendation was "don't use VLCDs [very low-calorie diets] to manage obesity". The headline grabber was "Give weight-loss surgery to obese patients on NHS to curb diabetes, says Nice".

Until this announcement, the guidelines for eligibility for bariatric surgery were either a BMI (body mass index) of 40-plus or a BMI of 35-plus with what is called a co-morbidity. The latter is typically type 2 diabetes. Nice is now recommending that people who are merely obese (a BMI of 30-plus), with recent-onset type 2 diabetes, should be considered for surgical intervention.

There appears to be some dispute over the impact of this recommendation. Approximately 8,000 bariatric surgery operations were performed in 2010-11. Diabetes UK estimates that 460,000 people meet the current criteria and 850,000 will meet the new threshold; and there may be even more because type 2 diabetics of Asian origin will be eligible at a lower BMI.

When asked about the numbers, Professor Mark Baker from Nice told the BBC: "It would be between 5,000 and 20,000 operations a year, but we haven't done the modelling." I suggest that Nice starts modelling.

With 2.9 million diabetics in the UK, 95 per cent type 2 and the majority of these likely to have a BMI of 30-plus, the Diabetes UK estimate of candidates for surgery seems conservative. Even if there are "only" 850,000 people to surgically alter, and even if operations are almost doubled to 15,000 a year, it will take 57 years to clear the backlog. Add to this the projected forecast of five million diabetics by 2025 and Nice may regret not modelling.

My first thought when I saw the headline was that you may as well put a plaster on a severed artery. This is not going to stop the problem. It shows no understanding about the problem. It does not address the cause of the epidemics that we – yes, we – have created among our fellow humans.

To understand the obesity epidemic we need to know when it started. In 1972, 2.7 per cent of UK men and women were obese. By 2000, 22.6 per cent of men and 25.8 per cent of women in the UK were obese. What happened?

The short answer is that we changed our dietary advice. We demonised fat and eulogised carbohydrate. "Base your meals on starchy foods," we were told. Obesity has increased up to 10 fold since – coincidence or cause?

To show just how much carbohydrate should be consumed, the Department of Health launched something called "The Balance of Good Health" plate in 1994. This was tweaked by the Food Standards Agency and re-launched in 2007 as the Eat Well Plate. I call it the eat badly plate. In among the chocolate, sweets, biscuits, Battenberg cake, Victoria sponge, cornflakes, baked beans, flavoured yoghurts and even a can of cola, I spotted just two or three items that wouldn't have an impact on blood glucose levels. Then we wonder why we have an epidemic of type 2 diabetes.

Diabetes can be defined as an impairment of the body's glucose-handling mechanism. When someone has an inability to manage glucose, why, why, why would you advise them to base their meals on glucose (starchy foods)? It's not just bad practice, it's medical malpractice in my view.

Our current dietary advice has produced epidemics of both obesity and diabetes. In terms of direction of causation, I think that obesity can cause diabetes and diabetes can cause obesity. However, but for the unprecedented level of carbohydrate recommended in the so-called "developed" world, we would have neither.

Dr Natasha Campbell-McBride calls the gut the second brain in the body. We mess with digestion of nutrients and hormone feedback loops at our peril. We don't need bariatric surgery at all, let alone inflicting it on another million or so human beings. We just need to dump our current dietary advice and stay true to evolution.

We have eaten real food – that provided by nature – since Australopithecus Lucy first walked upright, an estimated 3.5 million years ago. We should be eating meat, eggs and dairy from pasture-living animals, fish, vegetables, nuts and seeds and fruits in season. We did just fine until man started messing with his own food chain.

If you are left wondering why Nice would recommend removing half of someone's stomach before advising them to eat real food, I have a theory. Just as the Government will stick to its "Responsibility Deal" – better called Irresponsibility Deal – to keep the fake-food companies happy, so a conflicted guideline development group will act according to conflicts.

In February, Nice recommended a substantial increase in the number of people who should be given statins. I discovered that eight out of 12 of its panel members had conflicting relationships with the drug companies.

So this angle was an obvious one to check for the latest guidelines. Sure enough, six out of 14 members of this latest panel have conflicts of interest. Four are bariatric surgeons and two are happy customers of bariatric surgery. One of them is Ken, the nice chap I met at the obesity conference, or should that be the Nice chap representing the bariatric surgery industry.

Zoë Harcombe is the author of 'The Obesity Epidemic'