endoscopists are already successful at treating obese patients , who are more at risk of gastrointestinal ( gi ) diseases such as cancer than the general population , and assessing their gi condition before bariatric surgery .
they are also increasingly efficient when helping with postoperative complications such as leaks , stenosis , or weight regain after various bariatric procedures .
moreover , it seems today that they may claim a role in primary treatments of obesity , while purely endoscopic methods are available and upgraded on a regular basis . as recently stated by the american society for gastrointestinal endoscopy ( asge ) ,
endoscopic bariatric therapies offer a viable , safe alternative for patients who have been unsuccessful at weight loss with diet and exercise
. they may also be appropriate for patients who are not suitable for , or are unwilling to undergo , a more invasive surgical procedure .
if bariatric endoscopy may be viewed as a competitor to bariatric surgery , current trends suggest the development of combined strategies as well as mutual assistance when it comes to procedures that require both endoscopic and surgical skills .
although expanding , the array of bariatric techniques does not meet the current needs of morbidly obese patients ( class ii to iii obesity ) .
resources for spreading this type of surgery are lacking , while more basic and general procedures are not even available throughout the world . besides
, they are often disregarded by a majority of patients because they are deemed  excessive . 
somehow , futile quarrels and surgical discrepancies are abundant , for example : should we do a hiatal hernia repair in the mean time as a sleeve gastrectomy ? should we only do the regular roux - en - y gastric bypass or can we afford the omega - loop bypass ? in the meantime , and paradoxically , bariatric surgery claims to expand its boundaries , for instance taking on class i obesity ( international federation for the surgery of obesity and metabolic disorders [ ifso ] statement , 2014 ) .
several issues have been raised : should minimally invasive procedures take over ? when and how should this happen ?
typical surgical concepts as well as new ones are valuable assets because they make it possible to establish benchmarks and fruitful combinations .
one may cite new concepts like digestive neuro - stimulation ( theoretically adaptable endoscopically ) , new operations ( e.g. , laparoscopic greater curve plication , a debatable procedure , but with highly relevant endoscopic applications ; sleeve gastrectomy associated with ileal transposition ) .
new technical approaches are on the spot as well ( e.g. , single incision laparoscopic surgery , robotic adjunction ) . three - dimensional and/or enhanced imagery
last but not least , research is being carried out regarding operations in - between surgery and endoscopy , typically the natural orifice transluminal surgery procedures , e.g. , gastro - jejunal anastomosis through stents or magnets . on the other hand , other fields will contribute to any bariatric procedure , such as patient monitoring ( smartsensing ) results from the rapidly progressing field of internet on things business .
although in its infancy , the possibility to continuously monitor several health parameters could find potential applications in obese patients , before or after any kind of weight - loss procedure .
coaching tools are not to be ignored in a time when the importance of physical activity is stressed more often ( e.g. , vibrating platforms ) .
so far , no drug has challenged the results of surgery , but some are currently being tested and even drugs that have been discarded have been proven useful in combination with bariatric techniques . moreover , fundamental research has benefited from surgery and could contribute to weight - loss by itself ; for instance , microbiota transplantation or brown tissue manipulation .
none of them has yet fulfilled the requirements of a typical bariatric treatment , with sustained weight - loss and regression of comorbidities in the long run .
understandably , they may act as a bridge to more complex surgical procedures and/or attract patients who are not eligible for surgery .
countless procedures have been initiated , but so far very few have met efficacy criteria with published results .
( 1 ) intra - gastric balloons : the initial prototypes were not satisfactory , but since the early nineties one may consider that these devices are reliable .
they are usually implanted for 6 months . only the orbera balloon ( apollo endosurgery inc .
, austin , tx , usa ) has been thoroughly reviewed , and was recently analyzed by the asge , with a systematic review and meta - analysis using diagnostic and therapeutic thresholds established in 2012 as a part of its preservation and incorporation of valuable endoscopic innovations initiative .
based on a meta - analysis of 17 studies including 1,638 patients , the % excess weight loss ( ewl ) at 12 months was 25.44% ( 95% confident interval [ ci ] , 21.47 to 29.4 ) , with three randomized control trials ( rcts ; difference in % ewl of 26.9% in favor of balloon over control ) .
while mostly deemed a safe procedure , one must not forget the adverse events that may occur with a balloon ( fig .
this can be achieved through refilling the balloon , for instance with the spatz balloon ( spatz fgia inc . , jericho , ny , usa ) , or designing a double - balloon volume ( duo - shape balloon ; reshape , san clemente , ca , usa ) .
perhaps the most interesting devices will be the ones that can be swallowed without endoscopy and anesthesia ( obalon ; obalon therapeutics , carlsbad , ca , usa ) , and even possibly self - excreted ( allurion - elipse , unpublished data ; allurion technologies , el segunto , ca , usa ) .
( 2 ) gastric partitioning achieved by endoscopic means is a new concept that might be the most promising .
theoretically a fully stapled pouch such as achieved by surgical means can be transposed through endoscopy .
this has even been performed with a device that no longer exists ( toga ; satiety inc , palo alto , ca , usa ) . for the time
being , the most promising technique seems to be gastric plication , with two competing devices : usgi - pose ( usgi inc .
, san clemente , ca , usa ) and apollo - overstitch ( apollo endosurgery inc . ) .
the first one ensures a partial plication with separated transmural stitches and anchors placed along the upper part and the antrum ( fig .
the second uses several full - thickness stitches in a triangular pattern , cinched together and repeated along the fundus six to eight times ( fig .
both have been initially tested as re - do procedures for weight - regain after gastro - jejunal bypass , reducing the size of a gastric pouch , and/or gastro - jejunal anastomosis .
while the first entails deep and reliable plications , the second ensures a more global shrinking of the lumen with few gaps , and thus may be compared to a bariatric surgical plication ( fig .
the most recent and significant experiences with primary cases have been reported by espinos et al .  
lopez - nava et al .   reported 50 patients , 13 with a follow - up of more than 1 year .
( 3 ) the metabolic field : these techniques aim at mimicking the metabolic effect of the surgical gastric bypass on type 2 diabetes , which relies mostly on duodenal exclusion from food passage .
duodeno - jejunal bypass - sleeve ( djbs ) , also called endo - barrier ( fig .
5 ) , has been the most studied of the new devices for the past few years , and has also elicited a comprehensive report from the asge .
it consists of a 60 cm jejunal tube that is anchored to the proximal duodenum and retrieved 12 months later .
three studies including 105 patients have shown a % ewl of 35.3% at 12 months , and four rcts showed a difference in % ewl of 9.4% in favor of djbs .
( 4 ) other devices can be mentioned but have not yet generated enough data : the endo - aspire consists of an endoscopically - placed gastrostomy tube and siphon assembly . the food is conveniently stored and then flushed .
patients aspirate gastric contents 20 minutes after meal consumption , removing about 30% of ingested calories .
trans - pyloric materials are also being experimented with , as well as various intra - luminal restrictive devices .
typical surgical concepts as well as new ones are valuable assets because they make it possible to establish benchmarks and fruitful combinations .
one may cite new concepts like digestive neuro - stimulation ( theoretically adaptable endoscopically ) , new operations ( e.g. , laparoscopic greater curve plication , a debatable procedure , but with highly relevant endoscopic applications ; sleeve gastrectomy associated with ileal transposition ) .
new technical approaches are on the spot as well ( e.g. , single incision laparoscopic surgery , robotic adjunction ) . three - dimensional and/or enhanced imagery
last but not least , research is being carried out regarding operations in - between surgery and endoscopy , typically the natural orifice transluminal surgery procedures , e.g. , gastro - jejunal anastomosis through stents or magnets . on the other hand , other fields will contribute to any bariatric procedure , such as patient monitoring ( smartsensing ) results from the rapidly progressing field of internet on things business .
although in its infancy , the possibility to continuously monitor several health parameters could find potential applications in obese patients , before or after any kind of weight - loss procedure .
coaching tools are not to be ignored in a time when the importance of physical activity is stressed more often ( e.g. , vibrating platforms ) .
so far , no drug has challenged the results of surgery , but some are currently being tested and even drugs that have been discarded have been proven useful in combination with bariatric techniques . moreover , fundamental research has benefited from surgery and could contribute to weight - loss by itself ; for instance , microbiota transplantation or brown tissue manipulation .
none of them has yet fulfilled the requirements of a typical bariatric treatment , with sustained weight - loss and regression of comorbidities in the long run .
understandably , they may act as a bridge to more complex surgical procedures and/or attract patients who are not eligible for surgery .
countless procedures have been initiated , but so far very few have met efficacy criteria with published results .
( 1 ) intra - gastric balloons : the initial prototypes were not satisfactory , but since the early nineties one may consider that these devices are reliable .
, austin , tx , usa ) has been thoroughly reviewed , and was recently analyzed by the asge , with a systematic review and meta - analysis using diagnostic and therapeutic thresholds established in 2012 as a part of its preservation and incorporation of valuable endoscopic innovations initiative .
based on a meta - analysis of 17 studies including 1,638 patients , the % excess weight loss ( ewl ) at 12 months was 25.44% ( 95% confident interval [ ci ] , 21.47 to 29.4 ) , with three randomized control trials ( rcts ; difference in % ewl of 26.9% in favor of balloon over control ) .
while mostly deemed a safe procedure , one must not forget the adverse events that may occur with a balloon ( fig .
this can be achieved through refilling the balloon , for instance with the spatz balloon ( spatz fgia inc . , jericho , ny , usa ) , or designing a double - balloon volume ( duo - shape balloon ; reshape , san clemente , ca , usa ) . perhaps the most interesting devices will be the ones that can be swallowed without endoscopy and anesthesia ( obalon ; obalon therapeutics , carlsbad , ca , usa ) , and even possibly self - excreted ( allurion - elipse , unpublished data ; allurion technologies , el segunto , ca , usa ) .
( 2 ) gastric partitioning achieved by endoscopic means is a new concept that might be the most promising .
theoretically a fully stapled pouch such as achieved by surgical means can be transposed through endoscopy .
this has even been performed with a device that no longer exists ( toga ; satiety inc , palo alto , ca , usa ) . for the time being , the most promising technique seems to be gastric plication , with two competing devices : usgi - pose ( usgi inc .
, san clemente , ca , usa ) and apollo - overstitch ( apollo endosurgery inc . ) .
the first one ensures a partial plication with separated transmural stitches and anchors placed along the upper part and the antrum ( fig .
the second uses several full - thickness stitches in a triangular pattern , cinched together and repeated along the fundus six to eight times ( fig .
both have been initially tested as re - do procedures for weight - regain after gastro - jejunal bypass , reducing the size of a gastric pouch , and/or gastro - jejunal anastomosis .
while the first entails deep and reliable plications , the second ensures a more global shrinking of the lumen with few gaps , and thus may be compared to a bariatric surgical plication ( fig .
the most recent and significant experiences with primary cases have been reported by espinos et al .  
reported 50 patients , 13 with a follow - up of more than 1 year .
( 3 ) the metabolic field : these techniques aim at mimicking the metabolic effect of the surgical gastric bypass on type 2 diabetes , which relies mostly on duodenal exclusion from food passage .
duodeno - jejunal bypass - sleeve ( djbs ) , also called endo - barrier ( fig .
5 ) , has been the most studied of the new devices for the past few years , and has also elicited a comprehensive report from the asge .
it consists of a 60 cm jejunal tube that is anchored to the proximal duodenum and retrieved 12 months later .
three studies including 105 patients have shown a % ewl of 35.3% at 12 months , and four rcts showed a difference in % ewl of 9.4% in favor of djbs .
( 4 ) other devices can be mentioned but have not yet generated enough data : the endo - aspire consists of an endoscopically - placed gastrostomy tube and siphon assembly . the food is conveniently stored and then flushed .
patients aspirate gastric contents 20 minutes after meal consumption , removing about 30% of ingested calories .
trans - pyloric materials are also being experimented with , as well as various intra - luminal restrictive devices .
companies and physicians alike have to overcome numerous barriers , which are present throughout the development process . regarding endoscopic devices , these barriers are particularly important .
many events are in a position to kill an innovative device : if the market has not been clearly identified , or is too small , sales will not meet the expectations ; likewise if the device is too complex , or too expensive for its application .
many interesting devices can be stalled if investors do not want to finance inevitable delays or if regulatory bodies request additional trials .
the adoption of a new device can take longer than anticipated , and training for experienced physicians might be complicated .
last but not least , any startup can be purchased by a major company in order to eliminate competition .
for instance , hormonal studies are already available , which suggest more or less strong metabolic effects that could match those of surgery .
have shown that after 24 weeks of implantation of the endo - barrier , patients had lost 12.71.3 kg ( p<0.01 ) , while hemoglobin a1c had improved from 8.4%0.2% to 7.0%0.2% ( p<0.01 ) .
both fasting glucose levels and the postprandial glucose response were decreased at 1  week after implantation and remained decreased at 24  weeks . in parallel , the glucagon , glucagon - like peptide 1 , and glucose - dependent insulinotropic hormone responses decreased and insulin levels did not change significantly .
mathus - vliegen and de groot   have studied the effects of a balloon in 42 patients . in group 1 ,
basal cholecystokinin ( cck ) levels decreased but meal - stimulated responses remained unchanged after 13 weeks of sham treatment . in group 2 ,
basal and meal - stimulated cck levels decreased after 13 weeks of balloon treatment . at the end of the second 13-week period , when group 1 had their first balloon treatment , they duplicated the initial 13-week results of group 2 , whereas group 2 continued their balloon treatment and reduced meal - stimulated cck release .
both groups showed reduced meal - stimulated pancreatic polypeptide ( pp ) secretions at t1 and t2 compared to t0 .
( 3 ) one may consider techniques that are ready but require additional studies , e.g. , endo - barrier , endoplication , and endo - aspire . on the other hand , some are not yet available ( or not anymore ) but they could become a priority provided research is carried out , e.g. , endo - rings ( teris device ; barosense , menlo park , ca , usa ) , endo - stapling ( ace method ; boston scientific corporation , natick , ma , us ) , transpyloric shuttle ( baronova , goleta , ca , usa ) , the satisphere method , and duodenal resurfacing ( fractyl , unpublished data ; fractyl , waltham , ma , usa ) .
( 4 ) facing the criticism of those in favor of  surgery for everyone is not the least important issue ! the current and most common position from the bariatric surgical community states that the efficacy , durability , and long - term clinical utility of endoscopic procedures remain to be established .
although essentially true , this statement overlooks the fact that a majority of obese patients eligible for surgery reject these procedures and/or do not have access to them .
companies and physicians alike have to overcome numerous barriers , which are present throughout the development process . regarding endoscopic devices , these barriers are particularly important .
many events are in a position to kill an innovative device : if the market has not been clearly identified , or is too small , sales will not meet the expectations ; likewise if the device is too complex , or too expensive for its application .
many interesting devices can be stalled if investors do not want to finance inevitable delays or if regulatory bodies request additional trials .
the adoption of a new device can take longer than anticipated , and training for experienced physicians might be complicated .
last but not least , any startup can be purchased by a major company in order to eliminate competition .
for instance , hormonal studies are already available , which suggest more or less strong metabolic effects that could match those of surgery .
have shown that after 24 weeks of implantation of the endo - barrier , patients had lost 12.71.3 kg ( p<0.01 ) , while hemoglobin a1c had improved from 8.4%0.2% to 7.0%0.2% ( p<0.01 ) .
both fasting glucose levels and the postprandial glucose response were decreased at 1  week after implantation and remained decreased at 24  weeks . in parallel , the glucagon , glucagon - like peptide 1 , and glucose - dependent insulinotropic hormone responses decreased and insulin levels did not change significantly .
mathus - vliegen and de groot   have studied the effects of a balloon in 42 patients . in group 1 ,
basal cholecystokinin ( cck ) levels decreased but meal - stimulated responses remained unchanged after 13 weeks of sham treatment . in group 2 ,
basal and meal - stimulated cck levels decreased after 13 weeks of balloon treatment . at the end of the second 13-week period , when group 1 had their first balloon treatment , they duplicated the initial 13-week results of group 2 , whereas group 2 continued their balloon treatment and reduced meal - stimulated cck release .
both groups showed reduced meal - stimulated pancreatic polypeptide ( pp ) secretions at t1 and t2 compared to t0 .
( 3 ) one may consider techniques that are ready but require additional studies , e.g. , endo - barrier , endoplication , and endo - aspire . on the other hand , some are not yet available ( or not anymore ) but they could become a priority provided research is carried out , e.g. , endo - rings ( teris device ; barosense , menlo park , ca , usa ) , endo - stapling ( ace method ; boston scientific corporation , natick , ma , us ) , transpyloric shuttle ( baronova , goleta , ca , usa ) , the satisphere method , and duodenal resurfacing ( fractyl , unpublished data ; fractyl , waltham , ma , usa ) .
( 4 ) facing the criticism of those in favor of  surgery for everyone is not the least important issue ! the current and most common position from the bariatric surgical community states that the efficacy , durability , and long - term clinical utility of endoscopic procedures remain to be established .
although essentially true , this statement overlooks the fact that a majority of obese patients eligible for surgery reject these procedures and/or do not have access to them .
a breakthrough from the basic research field is highly anticipated , and could come from any biological / drug research .
the implementation of stepwise strategies , making use of new and old techniques , some endoscopic , some surgical , represents what is actually done for the time being .
conceptual similarities are useful when figuring out such strategies . likewise , adjacent technologies ( e.g. , smartsensing for monitoring , or the development of robotic platforms useful for endoscopy and surgery alike ) could be proven instrumental .
could be enough in the near future , i.e. , the success of a single endoscopic device among those that are currently being tested .
this could come from one of the available tools . among the devices presented above or under development , we feel entitled to select three that are particularly promising : ( 1 ) the new balloons , e.g. , swallowable ones ; ( 2 ) the endoscopic plication ; and ( 3 ) the metabolic asset sleeve endobarrier .
( 1 ) the ethical frame should be kept in mind all along . according to the american society for metabolic and bariatric surgery
, the implementation of such new devices should be limited to clinical trials and peer - reviewed protocols .
( 2 ) for the time being , most of the current techniques that fit into this description have rather short - term effects , which are strongly influenced by external factors in a much more important way than regular bariatric surgeries .
atypical weight - loss trajectories may be observed more often in minimally invasive methods that achieve less important weight - loss .
short - term effects may be described under the term  micro - trajectories  : 3- to 6-month periods are commonly analyzed in this field versus 1 year - period in typical surgical procedures .
the existence of an  on - off  pattern ( the device being active or not for a variable duration ) makes it more complex to analyze weight - loss curves .
such an effect can be observed in typical surgical procedures as well ( e.g. , gastric banding , gastric neuro - stimulation ) . paradoxically , weight - loss may be de - connected to the  on - off  pattern in some cases ; for instance , some patients continue losing weight when a balloon has been removed .
can we define the causes of atypical trajectories ( possibly control effects , center effects , or behavioral effects ) ?
caution is in order when evaluating the benefits of a given technique and its safety profile , and when designing the methods for rcts of obesity treatment .
most minimally invasive or endoscopic techniques for obesity treatment are not ready for prime time and require more observational or randomized studies , at least concerning primary procedures . however , they are already being successful as re - do procedures in cases of surgical failure .
a time - frame for step - strategies can be defined , allowing better long - term results and a favorable risk / benefit ratio .
one must advise caution and warn that re - do after endoscopic techniques might be more difficult than anticipated . keeping in mind a  bariatric schedule  and the necessity of experimenting with combinations , we assume that one success among some of the current devices that are being developed and tried could change our expectations , and attract investors .
 endoscopic procedures have been well - documented in the obesity field , but have not yet reached a sufficient level of evidence as stand - alone methods for treating obesity . 
 it is unclear if they should take over . 
 although expanding , the array of bariatric surgical techniques does not fully meet the current needs , and there are not enough resources for increasing surgery . 
 surgery is avoided by a majority of patients , so that less aggressive procedures are necessary . for the time being , relevant endoscopic methods include intra - gastric balloons , gastric partitioning ( endo - plication ) , and the metabolic field ( endo - barrier ) . 
 surgical novelties and basic research are also important contributors owing to their potential combination with endoscopy . 
 conditions have been listed for implementation of bariatric endoscopy , because innovation is risky , expensive , and faces ethical challenges . 
 a scientific background is being built ( e.g. , hormonal studies ) . 
 some techniques require additional study , while others are not ready but should be priorities . 
 steps and goals include the search for conceptual similarities and the respect of an ethical frame . 
 minimally invasive bariatric techniques are not ready for prime time , but they are already being successful as re - do procedures 
 . a time - frame for step - strategies can be defined , and more investments from the industry are mandatory . 