Heavyweight Contenders

The plusses (and perils) of weight loss surgery

by Cushla McKinney

In New Zealand, as in the rest of the Western world, the size of our collective waistline is expanding at an alarming rate. According to the 2006-2007 New Zealand Health Survey more than half of Zealand adults are overweight, with one in four of us classified as obese, in terms of the accepted Body Mass Index calculation. Despite this, there are few medical procedures other than abortion that raise such strong emotions as bariatric (weight loss) surgery. Suggestions that ‘stomach stapling’ should be more freely available under the public health system are generally met with howls of indignation from columnists, commentators and listeners to talkback and Radio New Zealand National alike.

Obesity, it appears, is considered a moral rather than a medical issue. The arguments fall into three main, intersecting categories:
1. Eating too much is a lifestyle choice, not an illness. Obese people do not need/deserve treatment for something they knowingly chose to do.
2. Surgery is a ‘quick fix’ for a problem that could be solved if patients just exerted a little self-discipline. Why should we pay for expensive operations when they should just take responsibility for eating less and exercising more? Treating it as a medical condition ‘normalises’ the behaviours and provides disincentives for people to make diet and lifestyle changes that could prevent surgery in the first place.
3. There is no point in such operations because patients are just going to put the weight back on again anyway.

Are these objections to publicly –funded bariatric surgery legitimate? Even if they are, does this justify withholding treatment from all but those who can afford to pay?

At the most basic level, people gain weight when they take in more energy than they expend. In today’s society, this is remarkably easy to do. Eating just 123 calories a day more than you need – that couple of biscuits or muesli bar at morning tea for example – is enough to cause a weight gain of just over 4 kg/year. Over the course of 20 years, this would add up to a whopping 82kg, more than enough to put you into the category of morbidly obese. Of course most of us don’t reach this stage – partly because we recognise what is happening and change what we do, and partly because our weight is highly regulated both at the metabolic and neurological level. We may gain a few extra pounds over the years, but in general we can with vigilance, limit this increase. Why then, are some people unwilling (or unable) to do so?

Weight and eating behaviour are the result of complex interactions between genetic, environmental, social, economic, psychological, and metabolic factors. It is easy to say that maintaining a healthy weight is a matter of acting responsibly, and the overweight should just act sensibly (eg have fresh fruit and vegetables rather than high-fat snacks in their cupboards to minimise temptation, or join a gym), but this is overly simplistic. Not only are snack and convenience foods heavily marketed and highly palatable because of their high fat, sugar and salt content, they are frequently cheaper than ‘healthy’ alternatives.

A recent study by the Auckland school of medicine found that if the cost of fruit and vegetables is reduced, people will buy more of them – which suggests that socio-economic considerations are an additional constraint on some people’s ability to make ‘good’ food choices. Similarly, although exercise is important in maintaining a healthy body, recent research suggests that it has only a limited role in weight control. Firstly, you have to do a lot of activity to lose a relatively small amount of weight (to lose a pound a week requires about 1hour of aerobic exercise a day). A 2002 report compiled by an international body of scientists suggests that 45-60 minutes of moderately intense exercise a day is necessary to prevent people from becoming overweight and obese, and 60-90 minutes to prevent a formerly obese person regaining the lost weight.

This is much higher than the 30 minutes a day currently recommended for reducing the risk of diabetes and heart disease. For many people, work and family obligations make this unrealistic, even if they have the motivation or discipline to exercise regularly. (Studies have also shown that more exercise people do, the more they tend to eat, either because they are hungrier, or because they think they have earned it.) Viewed in this light, obesity arises from a collective, rather than individual lifestyle, and for some people it is a situation where their choice is strongly influenced by external factors.

This is not to say that people cannot achieve lasting or significant weight loss through a self-imposed combination of dietary restriction and exercise, but for some people this may be easier than for others. Evidence suggests that genetics play a major factor in determining an individual’s weight. First-degree relatives of morbidly obese people are five times more likely that somebody from the general population to become obese, and this is not just because they grow up in an ‘obesogenic’ household. Identical twins are much more likely to be a similar weight that non-identical twins even when raised apart, and adopted children have BMIs closer to that of their biological than their adoptive parents. Recent research led by Professor Sir Peter Gluckman has shown that weight is also influenced in utero by maternal nutritional status.

When scientists first started looking for genes that are involved in weight regulation, they expected that most of these would be involved in metabolism. They hypothesised that naturally thin people would have variations that speeded up the rate at which their body burned food, while those who struggled with weight would have variations that favoured energy storage over utilisation. Much to their surprise, the majority of the genes thus identified actually act on the brain, and are involved in appetite regulation.

In hindsight, perhaps this ought not be so surprising. Hunger is the body’s way of signalling that energy stores are low, so our brain has to have some way of detecting our nutrient status and to induce us to respond appropriately. Consider what happens when you eat a meal. The resulting increase in blood glucose stimulates the production of insulin, which not only promotes the uptake and storage of nutrients by body tissues, it also acts on the hypothalamus, the region of the brain that is responsible for controlling appetite. Neurons produce anorexigenic (appetite-suppressing) chemicals that induce a sense of satiety and ‘turn off’ the orexigenic (appetite-inducing) pathways. [1] The stomach and gut also release hormones that tell the brain that you are fed.

Leptin, a hormone produced by adipose tissue, has a similar effect. As a person puts on fat tissue, leptin levels rise, reducing food intake and increasing energy expenditure. It also explains why dieting is so hard -the drop in leptin leads to increased appetite. Mutations in the leptin gene lead to severe obesity, as do defects in MCR-4, a protein that is involved in the down-regulation of appetite.

Of course such genetic defects are relatively rare, and result in extreme obesity. Most natural variations will produce only minor differences in appetite and/or metabolic rate. For example the recently discover ‘fat’ gene, FTO, accounts for about a 4kg difference in weight over a lifetime in people with ‘good’ or bad’ variants. Just because there is a genetic component to obesity doesn’t mean that people have no ability to alter their eating and exercise habits to limit weight gain.

However, if you place people in an environment where energy-dense food is plentiful, cheap, tasty and heavily marketed, it is easy to consume excess calories without even realising it. If you add to this a physiological urge to overeat, it is easy to understand why somebody would find it very hard to maintain a healthy weight. How many of us keep our New Year’s resolutions to watch what we eat for a week, let alone a lifetime? Since we are unlikely to change such environmental factors any time soon, is it fair to blame people for ‘giving in’ to biology?

In fact it could be argued that since we have created an obesogenic society, we have a moral obligation to help those people who are harmed by it. Ethicist Joseph Proietto likens controlling appetite by act of will to pushing a car uphill.

How easy it is to do depends on the steepness of the slope, and hunger is a very steep hill. Very few people, surrounded by plentiful food and bombarded by constant advertising designed to make them eat more, are able to sustain extended periods of hunger.

Healthcare in New Zealand is allocated on the basis of need rather than via values-based categories such as merit or worth. The drunk driver is rushed to the same ER as the passenger in the car she crashes into, and a smoker with lung cancer receives chemotherapy along side a woman with BRCA2 breast cancer. Thus, the key question is not whether a morbidly obese patient deserves surgery – but whether the operation is likely to be effective.

Regardless of whether obesity is a personal failure or a medical disorder, it is clear that being extremely overweight has significant personal and societal implications. Although there are legitimate arguments about the definition of obesity based on BMI because it doesn’t take body composition into account – many All Blacks would be classified as obese because of muscle weight – it generally correlates well with adiposity (fatness).

According to recent research, ethnicity also influences fat levels; a BMI of 30 equates to 43% body-fat in Pakeha women, 36% in Pacific Islanders and 34% in Maori. The distribution – as well as the amount of excess weight – determines whether a person is likely to suffer from weight-related illness; abdominal fat is more dangerous than peripheral body fat, and both waist to hip ration and waist circumference are also used to measure obesity.

Regardless of the measure used, however, increased weight carries with it significant health risks. Cardiovascular disease and a spectrum of symptoms known as ‘metabolic syndrome’ (type 2 diabetes, abnormally cholesterol levels and hypertension) are the most commonly recognised complications resulting from obesity, but there are many other complications that can severely impact on health and quality of life. These include both physical difficulties such as joint pain and breathing problems, and psychological problems such as social isolation and depression.

Somebody with a BMI over 30 is twice as likely to develop cancer, three times as likely to suffer coronary artery disease or stroke, and 18 times more likely to have type 2 diabetes than someone with a BMI of 20. Once a person reaches the stage of morbid obesity (a BMI of 40 or more, or a BMI of 35 or more with significant obesity-related illness), the risk of death doubles and life expectation decreases between 5 and 20 years compared to somebody with a healthy weight. Up to 7% of men and 11% of women in New Zealand were morbidly obese according to 2007/2008 figures, and it is estimated that 3153 people die each year from obesity-related heath conditions. In 1991, the direct health care costs of obesity in New Zealand were estimated to be $135 million (2.5% of the total health budget), and current estimates are that the costs of obesity are now about $450,000 per year.

Because of the extent to which morbid obesity and related illness curtails a person’s ability to exercise, the surgical management of morbid obesity works by limiting calorie intake. One approach is to wrap an inflatable band around the stomach (gastric banding), which decreases the size of the stomach and means that people feel full after eating only a small amount of food. Another is to limit nutrient intake by bypassing sections of the gastrointestinal tract, so that not everything that is eaten is absorbed.

The most common procedure used in New Zealand is the Roux-en-Y gastric bypass, which combines both techniques; the size of the stomach is reduced to 20-30mL (a normal stomach can stretch to over 1000mL) and is connected to the middle portion of the small intestine, decreasing the amount of food absorbed. Because food reaches the small bowel more rapidly, it also increases the production of ‘satiety’ hormones by the gut and decreases in the level of the ‘hunger’ hormone grehlin (although there is some disagreement over whether this a temporary or permanent change).

It may also alter pancreatic function, improving insulin responsiveness and enabling the body to better handle glucose. Swift post-operative resolution of type 2 diabetes has been reported in some studies, although longer-term improvement in glucose metabolism correlates with weight loss rather than the type of surgical procedure. Although there is a partial recovery of appetite over time, a meta-analysis published in 2009 found that gastric bypass patients lost an average of 61.5% of their excess weight within a year of surgery, and 71.2% at the three-year mark.

For gastric banding, the figures were 42.6% and 55.2% at one and three years respectively. This not only resolves or improved co-morbid conditions such as hyperlipidaemia, sleep apnoea, hyperuricaemia (a precursor for cardiovascular disease and gout) and diabetes, it can also have considerable effect on psycho-social functioning. Patients report improved social relationships, job opportunities, productivity and self-confidence, all of which greatly enhance their quality of life. In addition, lifestyle changes are also likely to influence other family members, reducing the chance that they too will become obese.

Although some of this weight may be regained over time, evidence suggests that most people will plateau at a level significantly lower than their pre-surgery weight; The most comprehensive study carried to date, the Swedish Obese Subjects (SOS) trial, which compared 2010 patients who received bariatric surgery to 2037 under conventional treatment (exercise, counselling, diet etc). Although weight loss was maximal 1-2 years after surgery and increased in the following few years, 15 years after the start of the study, those in the surgical group had reached a maintenance weight averaging 17-33kg (13-27%) lower than their original body weight depending on the type of surgery, while there had been no significant change in the control group.

Not only did their quality of life improve as symptoms such as joint pain and fatigue reduced, the compared incidence of diabetes, cardiovascular disease, sleep apnoea, cancer and overall mortality all decreased, relative to the control group. Although surgery costs up to $35,000 per operation, the Ministry of Health predicts that the costs of surgery would be cost neutral after 5 years and cost-saving after 8 years because of decreases in obesity-related disease. About 250 bariatric surgeries are carried out in the public system each year, the majority in the Auckland region, with another 400 paid for privately. The recent announcement of an additional $8 million over the next four years is expected to provide for an extra 300 operations, but the New Zealand National Service and Technology Review Committee recommended that a minimum of 915 bariatric surgeries should be carried out per annum.

Whilst there is a perception that surgery an easy solution for those who can’t be bothered dieting, this is far from the truth. Gastric surgery is a major procedure (Roux-en-Y procedures take close to 4 hours on average), and morbidly obese patients are at increased risk of adverse events because their physical condition is already compromised by their weight.

Operative mortality rates range from 0.1% for gastric banding to 1.1% for mal-absorptive procedures, with death most commonly due to heart attack or septicaemia due to leakage from the site of reconnection between stomach and gut. Post-operative complications are common, ranging from nausea and vomiting if patients eat too much or too quickly, to vitamin deficiencies caused by bypassing sections of the gut in which absorption usually occurs.

Roux-en-Y patients also often suffer ‘dumping syndrome’, an unpleasant combination of palpitations, light-headedness, fatigue and diarrhoea that occurs when they eat high-sugar foods (although this may contribute to dietary changes that assist in weight loss), and post-operative re-admission is not unusual. Other post-operative effects are just as challenging, if not immediately obvious. Further surgery to remove excess skin may also be required as the patient becomes thinner, for example.

Also, the reduced stomach capacity means that somebody who has had bypass surgery can only eat a few mouthfuls at a meal. Given the way much of our social discourse revolves around food (morning tea or lunch with your workmates, dinner with family, tea and scones at a friends place), sitting in front of an empty plate while everybody around you is eating can be a stressful and alienating situation. For somebody for whom food has provided an emotional comfort this can be particularly depressing, and increased suicide rates among bariatric surgery patients has been reported.

All of these factors need to be considered before a person decides to undergo surgery, and the fact that somebody is willing to go ahead despite the risks and consequences is testament to how poor their quality of life is.

The operation itself is, of course, only the first stage in the process. The patient still needs to lose the excess weight, a process that requires discipline and perseverance, and keeping it off means a complete (and permanent) change in lifestyle. Returning to the example of a person who has put on 82kg over the course of 20 years, losing that weight again would take drastic measures; fasting for a year, or jogging for an hour a day for 3.5 years (without eating more to compensate for the extra activity).

In order to lose a pound a week, he or she needs to use 500 calories per day than they eat. Although unable to eat much at one sitting, they still need to limit their calorie intake by avoiding high-fat and sugar foods, as well as avoiding snacking between meals. Somebody with binge-eating disorder might thus be refused surgery until they deal with their disturbed eating habits, in the same way that an alcoholic would be ineligible for a liver transplant whilst still drinking – not because they do not deserve it, but because the surgery would be unsuccessful.

Exercise is also an important part of the process. A systemic review of the literature found that regular physical activity is associated with increased weight loss at 12 and 24 months post-surgery. As yet there are no standardised guidelines on what amount or type of exercise is best, but patients need to be prepared to find ways to help them change their lifestyle in order to reach exercise targets. This not only means finding ways to stay motivated, but also to remove barriers to exercise – such as self consciousness, lack of time, or no access to a gym or park.

There is general agreement that pre-surgery evaluation should include a psychological assessment to ensure there is no underlying eating disorder, and the patient needs to receive information not only of the risks of surgery, but also the types of lifestyle changes that are needed. Unrealistic expectation of the ease or extent of weight loss is a common factor in limiting the success of surgery. A comprehensive plan for post-operative diet and exercise changes is also needed.

Although it has been suggested that prospective patients also commit to this regime, the same reasons that undermine a person’s ability to control their weight in the first place suggest that ongoing support is also important. Counties Manakau DHB is currently trailing a ‘wrap-around’ service that extends from 6 months before surgery to 12 months afterwards, providing psychological, social, whanau and (where appropriate) cultural support. This combination of medical and psychosocial approaches not only decreases the slope of the hill the patient is facing, it also means he or she is not struggling alone.

Of course, many people can lose weight by diet, exercise and behaviour modification, and bariatric surgery is an expensive and potentially dangerous intervention. But for some people it may be their only option. Current guidelines for access to the surgical procedure are very strict. Patients must have had a BMI>40 for at least 5 years, been unable to lose weight by any other means, and must understand the requirements not only of surgery, but also of the long-term changes in lifestyle that will be necessary after the operation.

Obesity is far higher among people of low socio-economic status, those least likely to be able to afford private healthcare. Not only is their access to bariatric surgery limited by funding constraints, they also face condemnation by others for their condition. This raises one final question that needs to be addressed, and that is why obesity is regarded with such moral opprobrium.

One of the most striking aspects of today’s society is the conflicting attitudes that exist around food and weight. Rates of anorexia and obesity are increasing dramatically in New Zealand and other Western countries, and both are the result of genetic, cultural and psychological factors. Despite this, we regard anorexics as suffering from an illness that needs treatment, while the obese are condemned as lazy, greedy and undeserving of assistance.

There are several possible explanations, not least that anorexia is predominantly a white, middle class problem while obesity is prevalent among the poor, Maori and Pacific people. However I think that the most likely explanation is that it is far easier to imagine oneself as eating oneself to death than it is starving. Food and eating is an enjoyable experience – so being overweight is regarded as a failure of self-restraint, a surrender to giving in pleasure, excess, and the deadly sins of sloth and lethargy.

Starving, on the other hand, is slow, painful and, outside certain religious or political contexts, apparently irrational. Yet we also admire an anorexic for her discipline and self control. Fasting and mortification of the flesh, the pursuit of the aesthetic over the physical has long been associated with spirituality and virtue, and these cultural values linger. Yet anorexia and obesity can be seen as opposite sides of the same coin. I hope that as we better understand the role of genetics and environment on obesity we can stop making moral judgements about people merely because of their weight.

Maybe in the future we will be able to reduce the impact of our obesogenic environment on susceptible individuals, but in the meantime we need to consider other ways of assisting those suffering from morbid obesity to regain control of their weight. For some, bariatric surgery is the only answer – and they should not be deprived of it or vilified for needing it, out of a misplaced sense that moral superiority.


[1] Fructose, a component of sucrose enters the metabolic pathway at a different point than glucose and does not trigger the same appetite-regulation signals. The widespread use of high fructose corn syrup as a sweetener in many foods may thus further contribute to weight gain.