How bariatric surgery reduces sugar cravings

23 November 2015

How bariatric surgery reduces sugar cravings

This is great news for the true sweetooths amongst you!  Yes, bariatric surgery fixes some of the sugar cravings that tempt you to go for the Anzac biscuit over the carrot stick! This is a true phenomenon as demonstrated by our friends the mice, but one that we have very little idea how or why it happens.  Dopamine seems to be the transmitter in question but how and why the signals occur in the first place is a mystery.  It is nice to know that there are laboratory reasearchers keen to get to the bottom of it and help us all in our quest towards a healthier life.  Bariatric surgery including Gastric Bypass, Sleeve and Lapband surgery are still the best ways we have of dealing with weight problems over the longterm.

Kind regards, Steph


Bariatric surgery curbs the sweet tooth by acting on the brain's reward system, according to a study published in the journal Cell Metabolism. The researchers found that gastrointestinal bypass surgery, reduced sugar-seeking behaviour in mice by reducing the release of a reward chemical called dopamine in the brain. The findings suggest that positive outcomes are more likely if sugary foods seem less rewarding after surgery.

"The problem of how and why bariatric surgery works has been perplexing scientists for years," said senior study author, Dr Ivan de Araujo of Yale University School of Medicine. "By shedding light on how bariatric surgeries affect brain function, our study could pave the way for the development of novel, less-invasive interventions, such as drugs that reduce sugar cravings by preventing sugar absorption or metabolism upon arrival in the gastrointestinal tract."

Previous research has shown how patients have reported a change in the type of food they preferred after weight-loss surgery. Although the different bariatric operations are effective at reversing obesity and diabetes, it is not entirely clear how these surgeries work. It is likely that there are a number of different mechanisms at play. Bariatric surgery is more likely to succeed when patients substantially reduce their caloric intake, and reducing sugary foods is an important part of these behavioural changes.

Building on past studies that showed that the brain dopamine reward system regulates caloric intake as well as findings from his team that nutrient sensing in the gastrointestinal tract stimulates dopamine release in the dorsal striatum, de Araujo set out to test whether bariatric surgery relies on the same brain circuitry to curb sugary food preference. They performed surgery in mice to bypass the first part of the small intestine, directly connecting the stomach to a lower section of the gastrointestinal tract. The same procedure is performed in humans, and it mimics the bypass component of the commonly used Roux-en-Y intervention, but no gastric pouch was constructed to limit food intake.

The gastrointestinal rerouting procedure performed in mice suppressed their sweet tooth by reducing sugar-induced dopamine release in the dorsal striatum, essentially diminishing the rewarding effects of sugar. Due to the addictive properties of sweets, infusions of sugar into the stomach would typically cause mice to persistently lick a spout that released a sugary liquid, despite the sensation of fullness. However, bypass surgery inhibited the sweet-seeking impulse, almost as if it prevented the sugar addiction from taking hold.

This graphic depicts how the duodenal-jejunal bypass surgery curbs sugar cravings by eliminating sugar-induced dopamine release specifically in the dorsal striatum. Credit: Han et al./Cell Metabolism 2015

Moreover, using optogenetics, an advanced neuroscience technique, to directly activate the dopamine neural circuit in free-living animals, the researchers saw a striking increase in sugar consumption, overturning the effects of bypass surgery. Mice that underwent this procedure consumed virtually no sweetener following sugar infusions into the stomach, but optical stimulation of the dorsal striatum caused the mice to plant themselves in front of the sugar spout.

"Our findings provide the first evidence for a causal link between striatal dopamine signalling and the outcomes of bariatric interventions," said de Araujo. "However, we certainly do not want to give the impression that we have an answer for how and why bariatric surgery works. Much more research is needed in this field."

de Araujo plans to directly compare the impact on the brain's dopamine cells produced by different types of bariatric surgeries.

"We hope our work will provide new insights into how different bariatric interventions may lead to a diverse repertoire of behavioural modifications," he added. "However, ultimately we would like to help patients lose weight and reverse their diabetes without going under the knife."

Individuals with type 2 diabetes should exercise after dinner

10 October 2015

Individuals with type 2 diabetes should exercise after dinner

Hi All,

Well this is a quirky one! Who would have thought that your decision on when to exercise could have consequences on the effectiveness of the exercise on a physiological level.  Nice to know, and switching to post-dinner exercise would be a pretty easy change to a daily routine to get the maximum benefits out of your exercise.  We all know that Type 2 Diabetes is closely linked to Obesity, and that significant and long term weight loss can be considered the best chance of bringing about a 'cure' for the diabetes in some people.  Obviously optimising exercise will contribute positively to helping with that weight loss, however, the one thing that diabetics can do that gives them the best chance of weight loss and subsequent cure of their diabetes is to consider weight loss (Bariatric) surgery.  Gastric Banding, Gastric Sleeve and Gastric Bypass surgeries (among others) have been proven to be true in many studies from different parts of the world.  If you want to talk more about these options then a Consultation is the best first step.  Obligation free, but more knowledge can lead to better decisions.  I look forward to seeing you soon!

Steph Ulmer


Type 2 diabetics can lower their risks of cardiovascular diseases more effectively by exercising after a meal, according to researchers at the University of Missouri (UM). Although it is known that exercise can benefit these individuals, little research has explored whether these individuals receive more benefits from working out before or after a meal.

“This study shows that it is not just the intensity or duration of exercising that is important but also the timing of when it occurs," said Jill Kanaley, professor in the MU Department of Nutrition and Exercise Physiology. "Results from this study show that resistance exercise has its most powerful effect on reducing glucose and fat levels in one's blood when performed after dinner."

The study, ‘Post-dinner resistance exercise improves postprandial risk factors more effectively than pre-dinner resistance exercise in patients with type 2 diabetes,’ was published in the Journal of Applied Physiology.

Kanaley and her colleagues studied a group of obese type 2 diabetics and consumed a moderate carbohydrate dinner on the evenings of the study.

On one occasion, participants performed resistance exercises before eating dinner and on a subsequent visit they exercised 45 minutes after eating dinner. Participants performed resistance exercises such as leg curls, seated calf raises and abdominal crunches.

Compared to levels on a non-exercise day, the researchers found that the participants who exercised before dinner were able to only reduce the sugar levels in their blood; however, participants who exercised after dinner were able to reduce both sugar and fat levels.

"Knowing that the best time to exercise is after a meal could provide healthcare professionals with a better understanding of how to personalise exercise prescriptions to optimise health benefits," said Kanaley.

They also found that improvements in participants' blood sugar and fat levels were short-lived and did not extend to the next day. She suggests individuals practice daily resistance exercise after dinner to maintain improvements.

"Individuals who exercise in the morning have usually fasted for ten hours beforehand," Kanaley said. "Also, it is natural for individuals' hormone levels to be different at different times of day, which is another factor to consider when determining the best time to exercise."

In the future, Kanaley said she plans to research how exercising in the morning differs from exercising after dinner and how individuals' hormone levels also affect exercise results.

Success of surgery depends on patients’ support network

6 August 2015

Success of surgery depends on patients’ support network

Hi All,

I love this type of research! It looks at the things that everyone wonders about and turns them into scientific research that can be quoted. I have always wondered about how the nearest and dearest of the people I operate on cope with the changes that my patients go through following life changing surgery such as Gastric Sleeve or Bypass or Banding. There is no denying that everything changes for people who I am privileged enough to operate on... mostly for the better. But that shouldn't be the assumption. It is reassuring to hear that this study backs up the assumption that most changes are positive and with positive spin offs for their support crew as well! It certainly echoes what I hear from my Bariatric surgery patients on a daily basis - this is "the best thing I have ever done" for myself, and "I should have done this years ago". More information is essential and if you think it would help you with the biggest decision you have ever made regarding whether Gastric Bypass, Sleeve or Banding surgery is right for you, then don't hesitate to get in contact with me. Time to quit wondering! Kind regards, Steph.



Bariatric surgery can lead to greater intimacy between patients and their life partners and could impact how successful surgery is, according to a study looking at the experience of couples after one of the partners underwent weight loss surgery. The findings, ‘Following Bariatric Surgery: an Exploration of the Couples’ Experience’, are published in the journal Obesity Surgery.

The study by Mary Lisa Pories and colleagues from East Carolina University is thought to be the first on obesity's impact on relationships since 2000, during which time surgical interventions, methods of support and the knowledge of the general public about bariatric surgery have evolved.

The research team interviewed ten couples about how bariatric surgery had affected the partners that had undergone surgery. All of the patients and their significant others viewed the surgery, and subsequent adjustments that needed to be made, as part of a team effort. They all described ways in which the partners supported and helped the patients care for themselves, including assistance with staying on track with the new routine.

"All of the couples felt their post-operative success was due to a joint effort on the part of both members of the couple," said Pories. She explained that the importance placed on couples' shared experiences of the surgery raises questions about how patients without active support systems manage post-operatively.

Several other themes also emerged. For example, couples highlighted the adjustment that was needed to adapt to their partners' significant weight loss. The couples also had more energy, and needed to adjust to new eating habits.

On an emotional level, the couples reported more positive moods and better self-esteem. They also reported sharing greater intimacy and affection, and being better able to resolve conflict. Their sexual relationships also improved and, in many cases, became more enjoyable.

Pories believes that a better understanding of how bariatric surgery impacts the dynamics of a couple's relationship could help physicians, nurses and social workers to support patients and their partners more effectively.

“This research provides greater insight into the experience of the couple than has been previously reported,” the authors concluded. “The use of qualitative research techniques offer new approaches to examine the biopsychosocial outcomes and needs of bariatric surgery patients. Further research is warranted in order to develop culturally appropriate interventions to improve the patient’s surgical and biopsychosocial outcomes.”


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