The SADI Procedure – The Newest and Most Effective Bariatric Surgical Procedure?

I recently took my team to visit Andrés Sánchez-Pernaute and Professor Antonio Torres at Hospital San Carlo, in Madrid, Spain. Professor Torres is a past president of IFSO (International Federation of Surgery for Obesity) and has a wealth of knowledge and experience on the long term outcome of different bariatric operations.
Andrés Sánchez-Pernaute developed a new procedure named the SADI. This is an acronym for ‘Single Anastomosis Duodeno-Ileostomy’, basically a description of the join between the duodenum and the small bowel that is central to the procedure.

sadi1Andrés developed this procedure after his experience with the Gastric Bypass, Sleeve Gastrectomy and Duodenal Switch. He observed (as we have commented on in past posts) that 10-20% of patient have a suboptimal result following bypass or sleeve surgery.


They either don’t lose as much weight as they had hoped, or they start to regain weight several years down the line from surgery. He also observed that the best procedure as far a weight loss, and sustainability of weight sadi3loss was the duodenal switch (DS). However, despite its efficacy in weight loss and also resolution of diabetes the DS is quite a significantly malabsorptive procedure. Following a DS there is usually only 1 meter of ‘common limb’ of small bowel.


This is the length of bowel in which both digestive secretions (from the pancrease and bile) and food are able to mix. In the average adult the small bowel measures between 6 to 8 meters in total length. We know that the after the DS patients are at risk of protein or vitamin deficiency unless they a

re assiduous with their diet. The main reason that I do not perform this procedure however is that the benefit that patient experience as far as extra weight loss is concerned is offset by a poorer quality of life due to a common complaint of increased frequency of bowel movement (6-8 times per day).s

The SADI procedure is a modification of all the bypass and the DS with the inclusion of the sleeve gastrectomy. The ‘common limb’ of small bowel measures 3 meters meaning that increased bowel frequency is much less of a concern compared to the DS. Initial reports suggest that the excess weight loss 5 years after a SADI procedure remains comparable to the DS at 90% (compared with 50-70% for the sleeve or bypass).

I have recently performed the first SADI procedure in the UK on a patient who was experiencing some weight regain following a previous sleeve gastrectomy that she had been performed in Miami. The procedure was successful and the patient was discharged home on the 2nd day after surgery. In fact my patient was so well that I gave her the all clear to visit the Wimbledon tennis championships the day after discharge! At recent follow up she remains very happy with the surgical outcome.sadi5

So in summary, I think that the SADI procedure may become the new gold standard in bariatric surgery. My team think that is has significant agvantages over the gastric bypass and sleeve gastrectomy. We will be reporting in the scientific literature of our experience in the future.

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How Safe is Bariatric Surgery?

Human evolution has been inexorably linked to our ability to select, prepare and cook food. These skills conferred to early man a significant metabolic advantage. Precooked foods require less digestive effort and therefore over time a smaller GI tract was evolved, leaving metabolic room for cephalisation and the development of a large brain. Unfortunately the hunter-gatherer humans of 150,000 years ago continued to develop their skills in food preparation resulting in the advent of agriculture and farming 20,000 years ago to the current explosion in the availability sugar and highly palatable processed foods.  Our relentless fascination and ability to grow and process foods, the very reason we where able to evolve to be humans in the first place, has led us to develop an obesogenic environment that is no longer suited to our health.



30% of the world’s population or 2.1 billion people are now overweight or obese 2.5 times more than malnourished people. If the current rise in obesity rates is continued then by 2050 half of the population of the UK will be obese (currently 23% of UK adults are obese). In 2014 the McKinsey Global Institute calculated that the cost of obesity to the UK economy was £47 billion per year. They compared the economic threat of obesity to the world as similar to smoking and armed conflict and more costly than alcoholism and climate change.

Morbid Obesity

It is well known that obesity causes a number of medical conditions. The central visceral adiposity characterised by the android fat distribution found particularly in men is a direct risk factor in the development of type II diabetes, hypertension and dyslipidaemia. This constellation of disorders, commonly referred to as metabolic syndrome, subsequently drives future risk of cardiovascular complications.

What is less commonly understood are the physiological changes that drive obesity and make it so hard for patients to lose weight permanently by ‘dieting and will power’.

Obesity, Genetics and Physiology

Genetic studies have suggested that some people are sensitive to an obesogenic environment and some people seem resistant to it. In fact genetic factors contribute to approximately 85% of a persons body mass index (BMI). In an obese person the normal homeostatic factors that should maintain energy balance break down. The development of leptin resistance results in a failure of the hypothalamus to respond appropriately to the signal that energy stores in the form of adipose tissue have exceeded requirements.


The physiological changes that occur when a person diets are also misunderstood.  The longer the period of calorific restriction the more pronounced the rise in ghrelin, a hormone secreted by the stomach driving appetite, and the lower the level of peptide YY, the satiety hormone, secreted by the small bowel. Increasing evidence suggests that in individuals that have tried low calorie dieting in order to lose weight the appetite and satiety changes that are experienced during a diet are in fact still present a year after dieting has ceased. This explains the common description of yo-yo weight fluctuation in response to dieting, with a slow an inexorable long-term weight gain. In 2014 the cumulative evidence that ultra-low calorie dieting is in fact counter productive in weight regulation led NICE (the UK commissioning advisory body) to warn against this form of intervention for obese persons.

In the face of the development of our obesogenic environment and the subsequent obesity pandemic, coupled with the failure of conservative forms of treatment for obesity it is not surprising that bariatric surgery has risen in popularity. In the US the number of bariatric procedures now exceeds the number of gallbladder operation with over 200,000 procedures performed annually.

But how effective and how safe is this type of surgery?


Development of Bariatric Surgical Procedures

Bariatric surgery is new in comparison to most established specialities. Since the start of the rapid rise in obesity rates in the 1980’s different types of surgical procedure have come into and then gone out of fashion, to be replaced by newer more effective procedures. The reason that we see more and more patients now requesting this type of surgery is that as the obesity crisis has worsened so the safety and effectiveness of surgery has improved.

Gastric Bypass

The gastric bypass is considered to be the ‘gold standard’ procedure in bariatric surgery. Due to concerns about the malabsorptive complications caused by jejuno-ileal bypass the gastric bypass was developed to be a hybrid procedure combining a much lesser degree of malabsorption combined with restriction in the capacity of the stomach. It has only recently become apparent however that malabsorption is not the prominent cause of weight loss after bypass. In fact the re-routing of the bowel causes significant changes to the secretion of the appetite and satiety hormones (ghrelin and PYY). The biological signal to eat in response to weight loss is therefore switched off, making weight loss much easier for patients.  In addition to this GLP-1, another peptide secreted in excess postoperatively, has a crucial role in glycaemic control and peripheral insulin sensitivity explaining the rapid improvement or resolution of type II diabetes following this procedure.

Despite the good results of the gastric bypass in weight loss and improvement in diabetes it still remained a procedure performed by the open technique until recently.  Open surgery carries the inherent risk of respiratory complications and DVT / PE. These risks are amplified in obese patients. The procedure was painful and required an extended in-patient stay. Therefore risk remained significant until the advent of laparoscopic surgery in the late 1990’s.

Laparoscopic Gastric Bypass

The gastric bypass, initially performed as an open operation, was increasingly performed laparoscopically in the early 2000’s. Throughout the decade with further developments in training and technology, including high definition monitors, advanced stapling devices and advances in thermal dissection technology the safely of the bypass improved. A procedure that we knew to be effective in the long term, with good long term follow up data from the open era of surgery, could now be performed with significantly decreased pain and morbidity, leading to a much faster recovery.

Laparoscopic Sleeve Gastrectomy

The sleeve gastrectomy has risen to become currently the most commonly performed bariatric procedure worldwide having recently superseded the laparoscopic gastric bypass in popularity. The sleeve procedure has seen a meteoric rise in popularity considering that it was rarely being performed only 5 years ago.

sleeveThe procedure is simple to understand and relatively easy to perform compared to the gastric bypass. Both patients and surgeons like this simplicity.

Performed laparoscopically the stomach is stapled and separated. The division of the stomach begins in the antrum and continues in parallel to the lesser curvature (the right sided concave border) to the lower oesophageal sphincter area. A new tube shaped stomach is created to replace the old cavernous stomach, reducing its capacity from approximately 2,000cc to 300cc. The redundant stomach is removed.The early (2 year) results for sleeve gastrectomy as far as weight loss and resolution of obesity related co-morbidities are comparable to the gastric bypass. These outcomes may be a surprise if the sleeve is considered to be purely a restrictive procedure, reducing the stomach capacity, however this procedure also works to change appetite and satiety drives. The resection of the body and the fundus of the stomach removes the mayor ghrelin secreting area from the GI tract. This is the hormone that leads to a voracious appetite in response to caloric restriction. Removal of this part of the stomach nullifies this appetite response.  In addition, the reduced capacity of the stomach encourages faster delivery of nutrients into the small bowel, stimulating an early and exaggerated PYY response from this area and producing an early feeling of satiety. With early delivery of nutrients to the small bowel comes a GLP-1 response similar to that seen in the gastric bypass and explaining the sleeve gastrectomies excellent effect on glycaemic control in type II diabetics.

What are the risks of bariatric surgery?

When deciding on any operative intervention, including bariatric surgery, surgeons must use their knowledge and experience to decide whether they are truly benefiting the patient with their intervention. They must calculate the risk (of significant complications) versus the benefit (improvements in health and quality of life).

The risks of surgery are dependent on several factors. These include; patient factors, the type of procedure performed and the expertise of the unit.


Benefits of bariatric surgery

Following gastric bypass or sleeve gastrectomy surgery patients routinely report that their lives have been transformed. After decades of struggles with dieting and yo-yo weight fluctuation their weight loss is maintained.

A good estimate of weight loss following either of these procedures is at least 70% excess weight lost.  For example man of average height (1.75m, 5 foot 9 inches) weighing 120kgs (18 stone 12 lbs) would expect to reset his weight to 89kgs (14 stone 1lb), or lower, within a year of surgery. This level of weight loss is generally maintained long term if patients are give appropriate lifestyle and dietetic education.


As well as good weight loss the sleeve and bypass procedures have an excellent effect on metabolic syndrome. Over 60% of diabetic patients will be off medication following surgery and the remainder will have better glycaemic control. The majority of patients with hypertension, dyslipidaemia and sleep apnoea will have resolution or significant improvement in their symptoms.

For women of reproductive age, fertility will improve following weight loss through bariatric surgery, pregnancy will be safer and there will be less chance of emergency caesarean section.

In addition to weight loss and better health, quality of life scores improve dramatically following gastric bypass and sleeve gastrectomy.




Risks Mortality <1 in 2000Complications

Early 1 in 100

Late 1 in 4

Mortality 0.7%. Low risk patients mortality 0.2%

Early complications 1 in 20

Late complications 1 in 20

Hospital Stay 1 night

2 nights

Recovery 1-2 weeks

2-3 weeks

Average Weight Loss 50% excess weight loss 70% excess weight loss 70-80% excess weight loss
Resolution or Improvement in co-morbidities T2DM 47%HT 43%

Cholesterol 59%

OSA 95%

T2DM 70% T2DM 90%HT 60-73%

Cholesterol 96%

OSA 94%



Obesity, and its associated problems, can now be safely treated by bariatric surgery. The risks of surgery have significantly reduced following the introduction of new procedures, new techniques and new technology. In appropriately selected patients treated by a specialist team in a large specialist centre the risks of bariatric surgery can now be equated to the risk of gallbladder surgery. In addition the rapid and sustained benefits of bariatric surgery are now being understood. The metabolic effects of surgery on appetite and satiety driving gut peptides and on metabolism have improved our understanding of obesity as a disease.

If a medical intervention that had such a dramatically beneficial effect on weight, health and quality of life and at such a low risk were discovered, it would be proclaimed the ‘trillion dollar pill’ by the pharma industry. For now, whilst we await this discovery bariatric surgery remains our only effective treatment for obesity.







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The Banded Gastric Bypass – Is it an improvement on the traditional bypass?

The gastric bypass is a procedure that my patients love. This procedure is known amongst surgeons as the gold standard because of its great results in really changing around peoples lives. I have performed several hundred laparoscopic gastric bypasses and I can report that almost all patients are extremely happy with the outcome, certainly in the short and medium term.
On average patients will lose 75% of their excess weight. The weight loss is seamless and easy because the procedure works to switch off the normal appetite response that is seen during dieting. Therefore weight loss is accompanied by a blunted appetite and not a voracious appetite.

However, some studies that looked at the outcome of the gastric bypass in the long term, ie after 5 or 10 years, have reported that a proportion of patients, maybe 10-20% of them, report a slow and inexorable weight regain. Many of the older American surgeons who have been performing gastirc bypass surgery for 20 years will concur with these studies. They will say that appetite returns to normal levels and that patients report being able to eat much larger volumes of food in one sitting. These factors, allied with patients reverting to old bad eating habits lead to weight regain.
Therefore the gastric bypass for all its impressive results in most patients does have a potential weakness in the long term.
fobi ring copyA new development in the bypass aims to prevent long term weight regain by ensuring that the restriction to eating too much too fast is maintained.
The procedure is called the banded gastric bypass. It is a simple addition to the bypass procedure and taked only a few minutes longer of operation time and confers minimal risk. The surgeon will place a small ring or band around the top of the stomach pouch (see figure). The ring is designed to sit comfortably around the small new stomach without causing any compression. Therefore in the short term a patient with a ring will have exactly the same felling of restriction as a patient without a ring. The message is it is not restrictive.

The ring will start to work only in those patients who are at risk of regaining weight. These are patients who typically would have been quite big before surgery, typically BMI greater than 50kg/m2. Once appetite returns and the honeymoon period of weight loss is over some patients start trying to overeat again. At first food may get partially stuck and things may be uncomfortable. However if this behaviour is continued then eventually the small stomach and the opening between the stomach and intestine will stretch. band3Over time the whole of the upper stomach can dilate up to be able to accommodate a large volume of food in a short time. The designer of the first ring, an American surgeon called Mal Fobi, calls this the ‘hot dog stomach’ because these patients can consume a hot dog in a couple of minutes.

band4It is only in these patients who attempt to overeat that the ring has an effect. By sitting as a guard around the stomach. Not compressing it but preventing stretching and long term stomach dilation.

band2Results for studies comparing banded gastric bypass to standard gastric bypass do indeed show that there is a real and significant improvement in long term outcome with the ring band.

I really like the gastric bypass as a procedure. It tick all of the right boxes. Great weight loss, change in appetite, resolution of diabetes, change in food preferences etc etc, the list goes on. However it does have this one potential weakness of long term weight regain in some patients. It is for this reason that I will be offering the banded bypass, also known as the Fobi ring, to patients in London who I think may benefit from this small improvement on a great procedure.



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The Obalon – A new advance in balloon technology

As you may have seen from the section of my website entitled novel procedures I do not think that the traditional intragastric balloon is a good and cost effective option for weight loss.

The traditional balloons have a volume of 600cc and are filled with fluid, making them quite heavy in the first place. They sit at the bottom of the stomach (the antrum) weighing it down and causing a partial blockage to gastric emptying. balloon In addition to this their sheer size causes a sustained and substantial reaction within the muscular wall of the stomach. The stomach is designed to grind and massage down any food particles so you can imagine the quite powerful contractions of the stomach wall as it reacts to the presence of such a large body within it. Patients will commonly report feelings of extreme nausea or pain and quite often require very early removal of the balloon (with no refund the their weight loss investment). Most of my colleagues do not offer the balloon for this very reason however there are still some surgeons and gastroenterologists and companies who still sell this service.

The Obalon is a new and novel type of balloon and I think that it may be less onerous for patients in terms of side effects whilst still having a good effect on weight loss.

The first advantage is that is does not require an uncomfortable endoscopy to be placed in the stomach. The subject swallows the balloon as a small capsule.capsule The capsule is attached to a micro catheter which is used to inflate it into a balloon once it has reached the stomach.

The second advantage is that the balloon is inflated with nitrogen gas (ie the gas that makes up most of the atmosphere that we breath). This means that it is weightless and floats to the top of the stomach.

Third, the balloon is much smaller than the traditional heavy balloon with a volume of 250cc compared to 600cc.

obalonThe small size of the balloon and the fact that it floats to the top of the stomach mean that there are far fewer side effects as far as nausea and stomach cramps are concerned. Also when the stomach is naturally full of food the upper part, ie the part where the Obalon sits, is stretched and produces a natural sense of satiety. Therefore this new balloon may work much more by the production of a pleasant full sensation rather than working to produce weight loss by inducing profound nausea.

Finally, and maybe crucially, the Obalon balloon system can adapt to naturally small or large stomachs by the insertion of a second balloon or sometimes even a third balloon until comfortable weight loss is produced.

The balloon, or balloons are removed (by endoscopy) at 3 months rather than 6 months and if allied to a sensible eating pattern will produce good weight loss.

The crucial factor for all balloons though is what happens when they are removed? The simple answer is that invariably people will slowly regain the pounds they have lost over time, just like if they had lost weight on a diet. Its depressing but if patients are not aware that lifestyle change is the crux of sustained healthy weight maintenance then inevitably there will be no long term effect.

I will talk in more detail about how to maintain weight loss in future posts.


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Welcome to my blog

The field of surgery is fast changing with many new and exciting developments. Particularly in the field of surgery to treat obesity and diabetes.

There are many exciting topics that I plan to discuss on this blog. It is designed to help patients understand and interpret some of the information out there in the press, in the scientific journals and even on the street.

If you have any comments or questions that you would like me to address on this blog please feel free to email these to me on


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