A fascinating journey through the cause, effect and treatment of obesity.
Josh : Craig – How should we introduce you?
Craig : My professional title is Upper Gastrotestinal and Bariatric or weight loss surgeon. I’m the director of a surgical weight loss clinic called OClinic, based in Crows Nest, which is a clinic that specializes in providing weight loss solutions to people with serious obesity, combining the procedures that we do with specialist aftercare, drawing on the expertise of practitioners in the field such as physiologists, dieticians as well as surgeons.
Josh : That holistic approach – is that new? It sounds innovative.
Craig : It’s not new, but it’s not as developed as it should be, and I guess surgical weight loss treatments are provided in various contexts – the way we do it involves in a regimented program with regular consultations with experienced medical practitioners, dieticians, and psychologists, commencing before surgery, and continuing in an ongoing way after the surgical procedure. I think this model of care is important for achieving best results with surgery, as obesity is a complex problem, and the underlying causes for it aren’t always the same for every person. We do know that there are significant contributions from a person’s family background, their decisions about food choices, level of education, and then there’s the whole baggage of emotional eating, using food for stress management, depression, boredom, which is is what we call ‘non-hungry eating patterns’. Obesity is such a complex thing that surgery alone is not going to provide the best solution- we need to address these other underlying issues as well.
What weight loss surgery provides is a tool that patients can then use to address these underlying issues more effectively. How weight loss surgery works is by reducing hunger and restricting calorie intake by helping with portion control. What it doesn’t do is solve for example emotional eating issues, or educate the patient about diet, it doesn’t make them exercise more – so all these things have to be driven by the patient, but supported by the clinic.
That combination of surgery plus ongoing aftercare is what gives us results.
Josh : You’re talking about the major benefits of surgery, in terms of increased satiety from smaller serves and experiencing less hunger, so you’re basically addressing that impulse of overeating half way – you’re basically stopping that process in it’s tracks, is that right?
Craig : Yes Josh, thats right- there’s no question that many people who struggle with their weight have elevated hunger levels and need oversize portions to feel full. Weight loss surgery directly helps with this.
Josh : Is that a hormonal dysfunction?
Craig : It can be. We don’t really understand that fully yet. Hunger is regulated by a part of the brain called the hypothalamus. That part of the brain is a very primitive part of the brain, basically it controls things like your thirst, hunger and your temperature. For instance. if you experience fluctuations in outside temperatures, your body’s core temperature will almost always remain constant, and that’s thanks again to the hypothalamus, as a regulation centre. The same is true for appetite. So if we do a big workout, – we get hungry! That’s our hypothalamus calculating that we’ve increased our energy requirements, because we’ve just had an increased energy expenditure. But in some patients, this algorithm is messed up.
Josh : Right
Craig : It may be because they have genetic basis for that, there have been some genes that have been identified that link into this idea of appetite dysregulation. Some patients will tell me that they feel hungry all the time, that they never feel full despite having a decent sized meal. Or they’ve got food preoccupation – so they’re constantly thinking about food. This food preoccupation can also lead to focus on more calorie-dense foods, because they’re going to satisfy the excessive overdrive for calorie intake, especially if that person has this appetite regulation problem.
The surgery that we’re doing has an impact on the hypothalamus, and it tames that hunger. We find that patients lose that excessive preference for the wrong foods after surgery. They sometimes claim that their “tastes have changed”, but really what happens is that their preference for high calorie foods has been toned down. And that then again provides better platforms for our dieticians and nutritionists to educate these patients on what is an appropriate choice – high protein, fresh fruit and vegetables, – when they’ve got that hunger controlled.
So how does this all work? The gut communicates to the brain in two ways : ones is along the nervous system, and the other way is through the hormonal system. There is a nerve called the Vagas nerve, it’s a very complex nerve that runs from the brain to the gut – we focus on the branches that are gut related, and by the time that Vagas nerve gets down to the stomach, 85% of those fibres within those nerve trunks are actually bringing information back from the stomach to the brain. So only 15% are bringing information down to the gut. They are sensory nerves, so they are constantly feeding back what’s going on to the brain, so when you last ate, what you ate, how much you ate – all that information is brought back constantly via these Vagas nerves.
Josh : That sounds extraordinary.
Craig : So we call these Vagal Afferents, and what our surgery does is tap into that system – it modulates it. For instance, with the adjustable gastric band, which is a silicon ring placed on the top of the stomach, and it actually squeezes on those nerves, and by doing that it creates a nerve blocking function. So it interrupts those hunger signals coming from the stomach to the brain, and patients are then reporting that they’re feeling less hungry. This has been checked in what’s called a binded randomized trial, where patients with a gastric band randomly had either fluid put in or removed from their bands to squeeze more or less on those Vagal nerves, and then had to do hunger scores. The band was then adjusted a second time, again without them knowing whether fluid was being put in or removed, and patients had to do their hunger scores again. What we found was that when you filled up the bands to squeeze those nerves tighter – patients felt reliably less hungry.
Josh : That’s really interesting. From a non-medical perspective, as soon as you hear the term ‘gastric band’, the assumption is that it’s just reducing the size of the stomach. But the impact on squeezing the nerve, and the reduction in hunger signaling – is it 50% about reducing the specific area available to the stomach, and 50 % nerve signaling – or would you say it’s more nerve signaling?
Craig : It’s probably about 50 / 50. But as you just said – the idea of the band modulating the appetite and not being a purely restrictive device – that’s something that’s also fairly new for us. When the band was first developed in the 1980’s it was thought of as a simple way to get a smaller stomach- to partition the stomach into a smaller stomach at the top with the larger one below, in a way that was reversible and had very little risk because the stomach wasn’t physically divided to achieve this. What’s happened over the last 20-30 years, is the band has been moved higher up, towards the top of the stomach, where those Vagas nerves are denser, so now the amount of stomach above the band is actually extremely small – we call it a virtual stomach. It has the capacity of about one mouth of food at a time only.
Josh : Wow!
Craig : So when patients with the band eat something, each mouthful momentarily occupies that little virtual stomach, and when it does, that little stomach pouch slightly expands and buldges, and then the nerves in the wall of that stomach then activate. And they then tell the hypothalamus that a big meal has been placed inside the stomach, rather than what we’ve really got: a small mouthful inside the virtual stomach. This mouthful of food then gets pushed through into the main stomach below the band and get digested normally, and the person eats another mouthful, which repeats the process. So each mouthful is only spending about 30 seconds of time inside that little stomach pouch.
Josh : But it’s enough to stimulate that signaling?
Craig : Correct. And then the signaling stops as the food moves on through, and then you have the next mouthful of food and the same signalling starts up again. We believe that after you’ve had a series of these signaling events, you go from having temporary satiation to more long term satiation. And it seems like the magic number is somewhere between 10 – 15 mouthfuls of food. When a person has had this amount of food, and may really have only been a cup of so of food, they get a genuine sense of satisfaction with that portion which feels like a big meal, and that’s sustained for 4-6 hours. That’s all through the nerve signaling. The mechanical effect of the band really comes into preventing binging and gorging.
Josh : Right.
Craig : This is where the band gives a ‘speed hump’ effect, so that big mouthfuls of food can be consumed quickly and drop straight down into the stomach, and if patients try to do that they get very uncomfortable. They feel tightness in the chest, they feel nausea and if they persist, they’ll bring up that mouthful that won’t go through the band. So the band does encourage patients to eat more slowly, chew their food properly. So with the band it becomes quite impossible for the patient to eat the same size portions that they used to eat.
Josh : Got it. You mentioned that there is the nerve pathway and the hormonal pathway – does the gastric surgery have any impact on hormonal signalling, leptin and so on?
Craig : It does, the hormone that is popular at the moment in weight loss surgery is called Ghrelin, which is a hormone that we discovered around ten or so years ago, which is made by the stomach in response to the stomach being empty. There are actually little cells in the stomach wall that secrete this hormone into the blood stream when the stomach is empty, and they circulate through the body and go up to the hypothalamus, where it binds to little docking stations called receptors, which then stimulates the patient to feel hungry. One of the popular surgeries that we do now regularly is called the Sleeve Gastrectomy, or gastric sleeve. That involves actually dividing the stomach into two, and removing that unwanted side.
Josh : OK
Craig : The side that we remove is the side that has a lot of the Ghrelin producing cells. So patients who have had this procedure done feel less hungry straight away, because their stomachs are no longer making the all that hunger hormone Ghrelin. This is one example of the hormonal effects of gastric surgery but it becomes even more important with another form of weight loss surgery called the gastric bypass. And so in that operation, nothing is removed from the abdomen, but rather the pathway for food is changed.
So in the normal anatomy, food comes down the gullet, across the reflux valve, into a big stomach organ which is the size of one and a half liters, let’s say, and later into the small intestine. The small intestine is about 5m long, before going into the colon, where the moisture is absorbed back, and we have a bowl movement. So with a gastric bypass, we divide the stomach into two, but we don’t take any part out. We have a small top stomach, with the rest of the stomach left as is, but it no longer received any food.
Josh : Got it.
Craig : Then we go into the small intestine, and divide that as well, and we bring the small intestine up, to join the top stomach. So food comes in as before, and comes into the stomach which now only has the capacity of about half a cup. The benefit of this is that the food no longer travels through the first part of the small intestine, which allows for a lot of funky things to happen in terms of hormones. This brings us back to the signaling and the hypothalamus. Another hormone that you mentioned was leptin, which is important in the long term regulation of hunger. So while we talk about ghrelin being the short term, in between meals type thing, leptin is more of an average, three month span regulator of hunger. This is why the gastric bypass has been so successful in terms of these kinds of surgeries as it taps into the hormonal side of appetite regulation and metabolism better than the other procedures.
So the gastric band works purely on the neuronal pathways, the sleeve gastreoctomy works on a bit of a combination of both, and then the gastric bypass even more on the hormonal pathways. All this knowledge and understanding is quite new, so the theory that it’s purely a mechanical or physical restriction is no longer the case.
Josh : That’s fascinating.
Craig : Within the medical community I think we’re still playing catch-ups with GPs and other specialists, and they don’t really understand this. So powerful are these hormonal changes that weight loss surgery is becoming referred to as metabolic surgery. We are going to keep developing this over the next 10 or 20 years, in order to be able to help not just overweight people, but also people with metabolic problems such as type II diabetes, and cholesterol problems. So people with these issues could also benefit from these types of procedures, even if they don’t have a weight problem.
Josh : That’s really interesting. Can we turn to diet for a second, I’d be really interested in hearing your opinion two aspects of the dietary question : 1. Are there dietary commonalities that you see coming into the clinic? And 2, in terms of the regime post surgery, is there anything specific that you can mention there?
Craig : Sure, one of the things that is very much a commonalty is a diet that contains way too much processed foods, sugars, and bad fats. We particularly see patients have a diet based around take away foods, soft drinks, chocolate, ice cream, sweets : high calorie, low nutritional foods. Part of this is because these foods lead to high doses of endorphins being released in the brain, which makes us feel good- a kind of ‘pick me up’. The limbic system is the part of the brain which has to do with emotion, and this is the area that gets that kick from high sugar, high fat foods.
Because these sugary, bad foods release endorphins, it becomes a pattern for the patients looking for a quick fix.
This is where that extreme preference for high calorie foods come in. This is why after surgery, we try to provide the best education we can around foods, and teach our patients how to deal with stress, tiredness etc in better ways rather than turning to unhealthy food. The combination of the surgery, education and psychological strategies then help people adopt the diet that will lead to a healthier lifestyle. What we advise them to do is increase their intake of whole foods, fresh fruit and vegetables, meats – particularly white meats and lean meats, eggs, yoghurt, and healthy, home cooked meals. Success for us is not just measured by how much weight a patient loses, but also by how much healthier their lifestyle becomes.
Josh : Right
Craig : One of the most important aspects of their new diet is protein – as protein is an important factor in suppressing appetite. It comes down to the way that protein is handled differently by the body than carbohydrates. Carbs are broken down by a peptide called amylase, which is made by saliva and your pancreas. So these start breaking down the moment that they’re in your mouth, and get absorbed by the gut wall and goes into your blood stream, and when they do that they cause a spike in the blood sugar levels, which is picked up by the pancreas, which in turns leads to the release of insulin.
Josh : So you mentioned that we do need sugar, it’s important for a number of things, but we can get adequate levels of sugar through natural sources like fruit. So how much is enough?
Craig : It’s hard to give a definite answer to that, it depends on the individual. Carbohydrate is essential for our energy needs, for example, the only fuel that the brain can use is sugar, but generally your diet should not consist of more than 65% carbohydrate.
Josh : Can it be created in the liver though?
Craig : There is a mechanism by where the liver can create sugar, and that’s called gluconeogenesis, but there is no question that we do also need an intake of sugar. But just to clarify, we are not talking about table sugar here, but natural sources from our food. Fruit, vegetables, all have a lot of carbohydrates. There is no need to deliberately go looking for extra sources of sugar. But coming back to insulin, the issue with the pancreas having to push out excess levels of insulin out, we can get to a point where blood sugar level becomes too low. Hypoclycemia can be a deadly problem. The body’s defense to this is to become hungry, to bring in more sugar. You’ll see that in diabetics that have a too high dose of insulin, they will in turn crave something sweet. This is the danger with having too much carbohydrate; insulin is pushed out, your blood sugar level becomes low, and you in turn crave something sweet. You feed this craving, and it becomes a vicious cycle. Another diet that is more protein based, will minimise these fluctuations. It’s more filling that the carbohydrate diet.
Josh : In terms of fats, and comfort eating, that are triggered by high sugar and fat foods. Do you have a view on good fats vs bad fats?
Craig : Which types of fats or sugars that cause the highest endorphin release is not really known, and probably varies from person to person. Someone may crave high sugar foods i.e. soft drinks, ice cream etc, and some may have a craving for savory foods i.e. cheeses, fried foods etc. Both of them are endorphin triggers, but there is no consistent pattern. In terms of different fats, we have worked out that fats are not all the same. Our thinking around fats have changed over the years, we went through a phase where we thought that the best fat was the polyunsaturated fat. I think we’ve moved on from this a little, more to the mono saturated fats, which you’ll find for example in olive oil, and the omega-3 fatty acids, found in oily fish. Saturated and trans fats are the most dangerous and should be minimised.
Josh : Last question, the paleo crew – they love their coconut oil, macadamia oil – how would you rank those compared to olive oil?
Craig : Macadamia oil has a lot of monounsaturated fats and therefore is considered a healthier choice. Coconut oil is a bit more controversial, has a bit of a checkered history. Its mostly saturated fat, which we should try to minimise in general, however some experts believe that the type of saturated fat in coconut is healthier. There is still debate around this, and the problem about making bold statements like this is that we don’t have the research to back it up. One thing I think history has always taught us: a little bit of everything and not too much of anything. And that a diet that is over represented by one individual food type is not the way to go. Balance, maximizing lean meats and protein sources, minimal carbohydrates, and choosing good fats.