Food addiction - craving may be hard-wired in the brain
14 January 2016
This study backs up something that I observe in my clinic regularly. Some of my patients tell me they don't have an 'off switch' when it comes to eating and they feel hungry all the time! This does suggest that there is a brain 'overdrive' going on and contributing to their increased calorie intake. The interesting thing is that following bariatric surgery in the majority of patients, this feeling goes away. Very few patients wake up saying that they feel hungry! Appetite suppression is a well known phenomenon following bariatric surgery and is likely to do with the removal of a large amount of the stomach derived hormones that stimulate appetite. The brain, however, also has a role and this study is investigating that. Imagine if in the future we have a treatment that can assist with weight loss by stimulating or suppressing parts of the brain. The potential for future developments of treatment of obesity are endless but still futuristic. The fact still remains that Bariatric surgery including Lap band, Gastric Sleeve and Bypass operations are the best treatments we have for obesity. But watch this space..!
An international group of researchers have found that food craving activates different brain networks between obese and normal weight patients, indicating that the tendency to want food may be 'hard-wired' into the brain of overweight patients, becoming a functional brain biomarker. The mechanisms associated with the desire to eat are poorly understood, although recent studies are beginning to suggest that the brain mechanisms underlying obesity may be similar to those in substance addiction, and that treatment methodologies may be approached in the same way as other substance addictions, such as alcohol or drug addiction.
"There is an ongoing controversy over whether obesity can be called a ‘food addiction’, but in fact there is very little research which shows whether or not this might be true,” said lead researcher, Oren Contreras-Rodríguez from Bellvitge Hospital, Bellvitge, Spain. “The findings in our study support the idea that the reward processing following food stimuli in obesity is associated with neural changes similar to those found in substance addiction. This still needs to be viewed as an association between food craving behaviour and brain changes, rather than one necessarily causing the other. However, these findings provide potential brain biomarkers which we can use to help manage obesity, for example through pharmacotherapies and brain stimulation techniques that might help control food intake in clinical situations."
Presenting their paper, ‘Brain correlates of the desire to food predict body mass index change in excess weight adults’, at the European College of Neuropsychopharmacology's annual conference in Amsterdam, the researchers from the University of Granada, Spain, and Monash University in Australia, looked for the functional connectivity differences in brain reward systems of normal-weight and obese individuals. In particular, it examined the association between the functional connectivity of the reward-based striatal brain networks during rest and the desire to high calorie food in excess relative to normal weight individuals, and whether such brain correlates predict weight increases in the excess weight individuals.
The study involved 81 participants (participants with overweight/ obesity = 39; normal-weight participants = 42) aged 33.34 years (46.9% women). Ventral and dorsal striatal connectivity were investigated using a validated seed-based multiple regression method. The resulting connectivity maps were compared between the study groups using two-sample models. Moreover, connectivity maps were explored in relation with the desire to consume high-calorie food-items, previously tasted in a previous buffet, and BMI change after a three-months diet using correlation and regression analyses, respectively.
The researchers gave buffet-style food to 39 obese and 42 normal-weight individuals. Later, they were put into functional MRI brain scanners and shown photographs of the food to stimulate food craving. The functional MRI scans showed that food craving was associated with different brain connectivity, depending on whether the subject was normal-weight or overweight.
They found that in obese individuals, the stimulus from food craving was associated with a greater connectivity between the dorsal caudate and the somatosensory cortex, implicated in reward-based habits and the coding of the energetic value of foods, respectively. However, with normal weight individuals, food craving was associated with a greater connectivity between different parts of the brain - between the ventral putamen and the orbitofrontal cortex.
The researchers then measured BMI three months afterwards and found that 11% of the weight gain in the obese individuals could be predicted by the presence of the increased connectivity between the dorsal caudate and the somatosensory cortex areas of the brain.
The researchers say the findings may point the way to using brain scans to diagnose the way some people respond to food, and new drug or brain stimulation treatments for obesity.
Access to surgery would improve health of thousands
7 January 2016
Happy New Year to you all! As a Bariatric Surgeon this type of article is music to my ears! These are the types of studies that should start to ring bells with those in charge of health funding allocation. Not only in the public health sector but also for the private medical insurance providers. In the long run, the financial pros and cons would have to weigh in favour of bariatric surgery as money well spent. As the article describes, bariatric surgery including gastric sleeve, gastric bypass and gastric banding, is "unrivalled" as the most effective treatment for hypertension and type 2 diabetes (and a lot of other medical conditions that occur directly related to being over weight). This is not news to me - I see it everyday in my rooms at BetterLife Surgery. The happiest patients I come across are my Gastric Sleeve patients who are finally getting control over their eating and drinking and consequently their weight. It is something we see often but it never fails to give me goose bumps. It is not the easy way out but it certainly gives you a push in the right direction towards a healthier life! If you would like to hear more, make an appointment to see me.
Bariatric surgery can reduce the risk of developing serious health conditions such as heart attacks and type 2 diabetes, as well improve existing conditions, according to a study published in PLOS Medicine. The paper, ‘Bariatric Surgery in the United Kingdom: A Cohort Study of Weight Loss and Clinical Outcomes in Routine Clinical Care’, is the result of the largest comprehensive study of longer-term outcomes post-surgery in the UK, and the paper suggests that widening the availability of bariatric surgery could boost the health prospects for thousands of people who are severely obese (BMI>40).
The research, led by the London School of Hygiene & Tropical Medicine in partnership with UCL and the UCLH Bariatric Centre for Weight Management and Metabolic Surgery, London, UK, states that bariatric surgery could potentially be used to prevent and/or resolve tens of thousands of cases of hypertension and type 2 diabetes, as well as prevent other obesity-related illnesses among the estimated 1.4 million morbidly obese people in the UK.
"Bariatric surgery is safe and produces unrivalled health benefits that are life-changing for patients and cost-saving for the NHS,” said study co-author, Professor Rachel Batterham, Head of the UCLH Bariatric Centre for Weight Management and Metabolic Surgery and the UCL Centre for Obesity Research. “Unfortunately, less than 1% of the patients who could benefit from this surgery currently receive surgery. This represents a major missed opportunity in terms of improving health and economic savings. Action is now needed to remedy this situation."
Using primary care records, the researchers compared weight, BMI and obesity-related illnesses between 3,882 bariatric surgery patients and similar control patients who did not have surgery, over an average period of three and a half years. They found that weight-loss surgery can significantly improve existing type 2 diabetes and reduce abnormally high blood pressure.
They also applied the findings to estimate that if the 1.4 million people believed to be morbidly obese in the UK had bariatric surgery, it could prevent;
- 80,000 cases of hypertension
- 40,000 cases of type 2 diabetes, and;
- 5,000 heart attacks over a four year period
They also report that 110,000 people with type 2 diabetes and 13,000 people with hypertension could significantly improve their condition.
"Obesity is one of the biggest health problems of our generation. Rates of cardiovascular disease, although slowly declining, are still alarmingly high while type 2 diabetes is on the rise, affecting 3.5 million people in Britain. Finding effective ways to tackle the obesity crisis is therefore a key public health strategy,” said lead author, Dr Ian Douglas from the London School of Hygiene & Tropical Medicine. “Whilst effective prevention is clearly needed, our findings show that as well as helping patients substantially lose weight, bariatric surgery improves serious obesity-related illnesses as well as reducing the risk of developing them. People having weight-loss surgery were 70% less likely to have a heart attack, and those with type 2 diabetes were nine times more likely to see major improvements in their diabetes. We also found positive effects on angina and the debilitating condition obstructive sleep apnoea.”
They also found that gastric bypass and sleeve gastrectomy were associated with greater weight loss than gastric band, with estimated four year weight loss of 38kg for gastric bypass, 31kg for sleeve gastrectomy and 20kg for gastric banding.
“Although we acknowledge that not all patients are suitable for bariatric surgery, it appears that better access to bariatric surgery, where appropriate, could lead to a considerable reduction in the burden of disease and substantial cost savings for the health system,” the authors write. “…Resolution of T2DM and hypertension was more common in people receiving gastric bypass or sleeve gastrectomy than in those undergoing gastric band surgery. For other outcomes, there was little evidence of differential associations by surgery type.”
How bariatric surgery reduces sugar cravings
23 November 2015
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.
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."
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