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Bariatric Surgery Reduces Response to Food Cues?

One of my favourite sayings to patients asking me about bariatric surgery is, “If you think surgery is a quick fix – don’t do it”.

That said, one of the consistent messages I hear from patients, who have undergone successful surgery, is about how it appears to affect their appetite, cravings and response to food.

This is particularly impressive, when you hear patients tell you how their previous obsession and desire to eat (many liken this to a addiction) before surgery, has been replaced with a surprising disinterest, not to say, indifference to foods that they previously found most tempting and rewarding.

This anecdotal report from post-surgical patients may well have a sound biological basis, according to a study by Christopher Ochner and colleagues from St. Luke’s Roosevelt Hospital, New York, NY, published in a recent issue of the Annals of Surgery.

The researchers used functional magnetic resonance imaging (fMRI) and verbal rating scales to assess brain activation and desire to eat in response to high- and low-calorie food cues in 10 female patients 1-month pre- and post-Roux-en-Y bypass surgery.

Following surgery, there was a distinct decrease in the activation of key areas of the brain known to be involved in the mesolimbic reward pathways in response to high-caloric highly palatable food cues (pepperoni pizza, fudge sundae).

These changes in brain imaging were mirrored by the participant’s subjectively reduced desire to eat in response to these cues, suggesting that the surgery may have resulted in substantial changed in the neuronal response mechanisms to such cues.

Thus, this study provides further evidence that bariatric surgery owes its success to neuronal (and hormonal?) mechanisms that go beyond simplistic notions of ‘restriction’ or ‘malabsorbtion’.

Indeed, as the authors point out, these findings are in stark contrast to previous findings in patients losing similar amounts of weight without surgery, who regularly report an increase rather than a decrease in their appetite and desire for highly palatable foods.

Clearly, as the researchers conclude, elucidation of exactly how gastric bypass surgery affects the brain’s reward system, may point to novel pharmacological targets that could lead to new medications that may ultimately reduce (or completely abolish?) the need for obesity surgery.

I would certainly be curious to hear from my readers how, in their experience, bariatric surgery affected their (or their patients’) appetite and cravings for highly palatable foods.

Edmonton, Alberta

Ochner CN, Kwok Y, Conceição E, Pantazatos SP, Puma LM, Carnell S, Teixeira J, Hirsch J, & Geliebter A (2011). Selective reduction in neural responses to high calorie foods following gastric bypass surgery. Annals of surgery, 253 (3), 502-7 PMID: 21169809


  1. I experienced that lack of interest in food and it was a godsend. It completely amazed me. However, it went away after the “honeymoon period”–for me, about 18 months. After that, the appetites and desires for certain kinds of food came raging back. Luckily for me, eating some of those foods in any significant amount (certain sugars and fats) resulted in horrific cramps and nausea (the dumping syndrome), so it became a form of aversion therapy. But the appetite did come back.

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  2. Bariatric surgery saved my life. Traditional dieting always resulted in losing tons of weight followed by rapid exponential gains. No matter what diet I was on (tried them all), I ALWAYS felt hungry. Not so with bariatric surgery. I opted for lap-band surgery. 3 years ago I was at circus freak proportions and weighed close to 600 lbs. I now weigh 290 lbs. I am NEVER hungry. I still get cravings for food that is not good for me, but when I indulge, it is in moderation. (a few bites of 1 piece of KFC chicken as opposed to an entire super sized bucket which I used to eat in one sitting and still feel I could eat more). My provincial government refuses to pay for lap-band. They consider it “cosmetic”. They will, however, pay for stomach stapling – a far riskier procedure in my opinion. In any event, I will reach my ideal weight in about 2 more years. The weight loss has been gradual and effortless.

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  3. I belong to a bariatric-surgery support website, and I’d say Wendy’s remarks are pretty typical for gastric bypass patients. I see a lot of them who report NO interest in food for the first several months, then a pronounced return of appetite.

    I had a different form of bariatric surgery, the Duodenal Switch. Pre-op, I was ALWAYS hungry—literally ALWAYS. However, since my surgery nearly eight years ago, I’ve always had what I think of as ‘normal’ appetite—I get hungry about 4 times a day, and I’m satisfied by normal portions.

    Due to how the DS is configured, there’s no dumping syndrome, and a very high malabsorption of fat (around 80% simply passes through the gut), so I do eat a high-protein, high-fat diet. This allows me to effortlessly maintain a loss of 170 pounds—AND have a satisfactory eating style.

    I’d love to see a long-term study done on appetite in the post-op patients with all four of the forms of weight-loss surgery—after all, if it IS possible to control appetite successfully through medication rather than surgery, wouldn’t that be wonderful?

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  4. I’m sure this is a really crude way of putting it, but it seems likely that the body knows that its digestive system is damaged and therefore tries to minimize eating while the injury heals. Once a new balance is reached – things have healed as well as they can – I’ll bet that appetite returns. Wendy’s experience seems to support that idea.

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  5. Of course people will have a depressed response to food cues at one month post-op. But that would be true following most operations. I had a bowel obstruction and lost only two feet of intestines, and during recuperation (several months), pizza was not my priority. Moreover, one month pre-op for bariatric surgery, when patients are preparing psychologically to NEVER eat the same again, it would make sense that they’re response to food cues would show heightened sensitivity. I’d like to see a study comparing one year pre- (or simply a control group) to one month post-op, then six months post-op, then one year, then 18 months, then two years, then two and a half, and so on. As Wendy points out, there is likely a honeymoon, after which surgery patients and non-surgical weight loss maintainers are on more equal footing, hormonally speaking. It would be good to know the range that this honeymoon period may take.

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  6. While we’re at it, let’s look at the hormone progression of people losing weight the “more traditional” way. I’m sure a scientific team could find fat volunteers, who have yo-yoed in the past and know how to lose great quantities of weight, who would participate.

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  7. I experienced the total lack of appetitie after surgery too. This lasted, for me, for just over a year. A warning to all, though – the appetite DOES return. For me it was almost like having a switch flipped. I can clearly remember wondering why I felt so hungry again. You truly do have to utlilze all the good habits you have built up until that time to avoid gaining weight back. I am now 4 years post op and have gained about 15 pounds back, but through working my program have not gained more.

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  8. I agree with DeeLeigh’s assessment, in part, that through the healing process, the body is focused elsewhere and the rewards of foods previously regarded as rewarding diminished. If a person’s life also becomes more “rewarding” (ie less stigma and alienation as they are “rewarded” for losing weight — maybe also taking on activities they previously felt were beyond their reach) — that too can help with rewiring. I think that once the brain perceives deprivation is at play, those reward centers are likely to get going again, that is, once the stomach has healed sufficiently to attempt to digest those foods again. The negative reinforcement of nausea, vomiting and other symptoms also plays a role, to be sure.
    I’m interested in knowing how to prevent the need for surgery in a holistic way. I think dieting leads people to be much heavier than they otherwise would be, as the body interprets it as a famine period and responds accordingly with no account to the current level of fatness the body has.
    I believe that dieting and stigma are the primary drivers of people gaining weight above and beyond where they would be, size-wise, were they to be eating and moving in balance with their environment and genetics. Some people would “naturally” just be larger, and could maintain a far better health at that “naturally larger state” than they would being driven by stigma to diet, and then driven by dieting to gain upwards of where they would otherwise be. Painfully, this starts for most “naturally larger” folks in childhood, and the struggle becomes a lifelong one.
    Our current food environment and physical activity-deprived setting sure doesn’t help matters, but I think that is true for all people, not only fat people.

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  9. Hi, Dr. Sharma 🙂

    I was wondering if this has ever been done before: Where doctors take a severely obese person give them a DEXA scan before their surgery , then many, many months after their bariatric surgery , another DEXA scan to determine how effective it was for pure fat loss . ( e.g. the precise level of adiposity is clearly shown as opposed to “weight” loss). Also comparing how much muscle and other solid mass was lost compared to fat tissue itself.

    I am wondering about that. It seems to be reasonable way of accessing the success.

    On another note, I enjoy your blog a lot because the quality information on it completely discredits the many Internet frauds out there scamming people writing diet books based on their own personal ectomorphic physiques.

    Here is an example for you of how nature plays the strongest role: Take Mike Tyson and Randall Cunningham for instance . Mike is an endomorph, Randall a pure ectomorph. They are WORLD’s apart. They only slighty enhance their natural builds a bit more by working out. If Mike lifts he will get thicker easier and gain weight. If Randall runs he will be even leaner a bit.

    Also, Randall would have a much harder gaining weight, whereas Mike Tyson would gain weight exceedingly easily. He also has a family history of obesity.

    Nature wins out over nurture ultimately of the two.

    Take care,


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  10. I have not had bariatric surgery. I have lost 33 lbs by diet. I find when I eat a mostly lean protein + veg diet I am only hungry before mealtimes, which is normal. When I eat a high carb diet, I find the more I eat the hungrier I get. Literally, I get restless and constantly hungry and I snack and eat all the time and I feel more and more unsatisfied. I do a day or two of eating only homemade beef and veggie (no potatoes) soup, and I can get over my cravings and then I can resume my lean protein/veg diet.
    I wonder if the lessening of hunger after Bariatric surgery might be related to the different food intake after surgery. A way to test this would be to have a control group of patients follow the same diet as a post bariatric surgery patient. Of course, they’d need medical supervision and nutrition supplements. They’d have to have the same food experience as the bariatric surgery patients (preparation, pre-op, fasting to mimic the food restrictions on the day of surgery and post-op, and then the tiny portions of specific foods.)
    I’m still morbidly obese. According to my recent physical I have no medical problems.
    I’d volunteer for an experiment like that.

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  11. I did have the sleeve back in Oct 2008 and for the first 6 month I couldn’t even tolerate the smell of chocolate or anything sweet (and I have a sweet tooth) …. then it slowly came back over the next 18 months and by around my second anniversary I could eat & tolerate 1/2 choc bar at a time (50g) if I had appropriate protein beforehand. Of course I had to try and see where my boundaries are 😉 but now I know and try not to push it but I definitely have days when I crave sweets. It is almost like circles …. once I am on the “sweet trip” it’s hard to get off and I have to cut out all my carbs for a couple days and the cravings are gone and I can slowly re-introduce a very low carb count and keep it in check for several weeks, sometimes a couple months until the carb intake increases and then the sweet trip starts again. I am now aware of it and can deal with it but it was scary when it happened the first few times.

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  12. Hi Dr. Sharma:

    I have a feeling that too many people who diet cut too many calories from there diet and once they stop actually trying not eat less they go back to eating too much. I feel this way because once I started to watch what I eat and how much I cut back to about 1600 calories and have beeen loosing 1 pound a week and do not feel restricted. There is a variation of 1600 to 1800 with a few days up at 2600 calories–those 2600 days are bad days.

    I try to keep regular meat to one serving per day to keep fat and calories down, and when I do want something like Fish and Chips or other do not go there foods I will have s set date for when I can indulge Like Sundays after the Kingdom Hall meeting or the next time I spend a day in Edmonton and eat in a restaurant for the day. It is not saying “no you can not eat that” it saying this ro that would be a better day to eat that. If I want a sweet treat I will only only by one versus at a store that sells only one versus buying 1/2 dozen at a budget store–because I know that if 1/2 dozen are in my home I will eat them at a time that is not weight managment proper.

    I do decide what I will eat long before I get to the restaurant and most of the time follow through, even though I have tough time following through on my meal plan. This is most likely an area affected by the symptoms of ADHD that I have.

    I enyoy both your blog and the feedback of other readers–sometimes I get annoyed at what they comment and I an sure that that is a two way street.

    Thank you very much

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  13. I have been able to maintain my body between 56-59 kgs for past 8 years. It fluctuates to 59 when I don’t behave interms of calories in and out. I feel key to weight maintenance is watching quality and quantity you eat. BTW I don’t deprive myself of any food that I like by just watching the quantity.

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  14. My gut instinct on reading this was, ‘I bet it’s got something to do with GLP-1!’

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  15. Dr. Sharma, I noticed this study was at 1 month post-op. I had RYGB in late June last year, with complications. Yes, my hunger was diminished greatly, initially at zero. My husband had to prompt me to eat. Now, one year later, I can’t say I get that feeling of extreme hunger, but my old habits are returning. I am fine all day long until I have dinner. The food I eat triggers something making me want more, especially after dinner. In the evening at TV time I need to munch on something as long as I am awake. To make matters worse I seem to always chose high calorie foods.

    I am feeling upset with myself. I can’t seem to stop myself from this horrible habit of munching after dinner. And it is on the sneek from the eyes of my family. I am beside myself and returning to bulima to avoid weight gain.

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