Does Glycemic Response to Food Really Affect Appetite?

A popular narrative by proponents of low-glycemic index foods is the notion that high-glycemic index foods lead to a surge in plasma glucose, which in turn stimulates a spike in insulin levels, resulting in a rapid drop in blood glucose levels and an increase in appetite (“crash and crave”). While this narrative is both biologically plausible and has been popularised by countless low-GI diets and products, the actual science of whether this story really holds true is less robust that you may think. Now, a study by Bernd Schultes and colleagues, published in Appetite, seriously challenges this narrative. The study was specifically designed to test the hypothesis that inducing glycemic fluctuations by intravenous glucose infusion is associated with concurrent changes in hunger, appetite, and satiety. Using a single blind, counter-balanced crossover study in 15 healthy young men, participants were either given an i.v. infusion of 500 ml of a solution containing 50 g glucose or 0.9% saline, respectively, over a 1-h period. On each occasion, the infusions were performed one hour after a light breakfast (284 kcal). I.v. glucose markedly increased glucose and insulin concentrations (peak glucose level: 9.7 vs. 5.3 mmol/l in the control group); peak insulin level: 370 vs. 109) followed by a sharp decline in glycaemia to a nadir of 3.0 in the glucose study vs. 3.9 mmol/l at the corresponding time in the control condition. Despite this wide glycemic fluctuation in the glucose infusion condition, the subjective feelings of hunger, appetite satiety, and fullness did not differ from the control condition throughout the experiment. Clearly, these findings speak against the conventional narrative that fluctuations in glycemia and insulinemia represent major signals in the short-term regulation of hunger and satiety. Or, as the authors put it, Our findings might also challenge the popular concept of low glycemic index diets to lose body weight. Advocates of this dietary approach often argue that large glycemic (and concurrent insulinemic) fluctuations induced by the intake of high glycemic index foods can trigger feelings of hunger and, thus, on the long run favor weight gain. Our results argue against this notion since the sharp drop in circulating glucose after the end of the glucose infusion remained without effect on hunger ratings, at least within the time period covered by our experiment. As they further note, these findings may explain why, “…several clinical dietary intervention trials have failed to show an advantage of low glycemic index dietary approaches for weight loss in overweight/obese subjects… Read More »

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Arguments For Calling Obesity A Disease #8: Can Reduce Stigma

Next, in this miniseries on arguments for and against calling obesity a disease, I turn to the issue of stigma. One of the biggest arguments against calling obesity, is the fear that doing so can increase stigma against people living with obesity. This is nonsense, because I do not think it is at all possible for anything to make stigma and the discrimination of people living with obesity worse than it already is. If anything, calling obesity a disease (defined as excess or abnormal body fat that impairs your health), could well serve to reduce that stigma by changing the narrative around obesity. The current narrative sees obesity largely as a matter of personal choice involving poor will power to control your diet and unwillingness to engage in even a modest amount of regular physical activity. In contrast, the term ‘disease’ conjures up the notion of complex biology including genetics, epigenetics, neurohormonal dysregulation, environmental toxins, mental health issues and other factors including social determinants of health, that many will accept are beyond the simple control of the individual. This is not to say that other diseases do not carry stigma. This has and remains the case for diseases ranging from HIV/AIDS to depression – but, the stigma surrounding these conditions has been vastly reduced by changing the narrative of these illnesses. Today, we are more likely to think of depression (and other mental illnesses) as a problem related to “chemicals in the brain”, than something that people can pull out of with sheer motivation and will power. Perhaps changing the public narrative around obesity, from simply a matter of motivation and will power, to one that invokes the complex sociopsychobiology that really underlies this disorder, will, over time, also help reduce the stigma of obesity. Once we see obesity as something that can affect anyone (it can), for which we have no easy solutions (we don’t), and which often requires medical or surgical treatment (it does) best administered by trained and regulated health professionals (like for other diseases), we can perhaps start destigmatizing this condition and change the climate of shame and blame that people with this disease face everyday. @DrSharma Edmonton, AB

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Arguments For Calling Obesity A Disease #3: Once Established It Becomes A Lifelong Problem

Continuing in my miniseries on arguments that support calling obesity a disease, is the simple fact that, once established, it behaves like a chronic disease. Thus, once people have accumulated excess or abnormal adipose tissue that affects their health, there is no known way of reversing the process to the point that this condition would be considered “cured”. By “cured”, I mean that there is a treatment for obesity, which can be stopped without the problem reappearing. For e.g. we can cure an ear infection – a short course of antibiotics and the infection will resolve to perhaps never reappear. We can also cure many forms of cancer, where surgery or a bout of chemotherapy removes the tumour forever. Those conditions we can “cure” – obesity we cannot! For all practical purposes, obesity behaves exactly like every other chronic disease – yes, we can modify the course or even ameliorate the condition with the help of behavioural, medical or surgical treatments to the point that it may no longer pose a health threat, but it is at best in “remission” – when the treatment stops, the weight comes back – sometimes with a vengeance. And yes, behavioural treatments are treatments, because the behaviours we are talking about that lead to ‘remission’ are far more intense than the behaviours that non-obese people have to adopt to not gain weight in the first place. This is how I explained this to someone, who recently told me that about five years ago he had lost a substantial amount of weight (over 50 pounds) simply by watching what he eats and maintaining a regular exercise program. He argued that he had “conquered” his obesity and would now consider himself “cured”. I explained to him, that I would at best consider him in “remission”, because his biology is still that of someone living with obesity. And this is how I would prove my point. Imagine he and I tried to put on 50 pounds in the next 6 weeks – I would face a real upward battle and may not be able to put on that weight at all – he, in contrast, would have absolutely no problem putting the weight back on. In fact, if he were to simply live the way I do, eating the amount of food I do, those 50 lbs would be back before he knows it. His body is just waiting to… Read More »

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Arguments For Calling Obesity A Disease #2: It Is Driven By Biology

Continuing in my miniseries on reasons why obesity should be considered a disease, I turn to the idea that obesity is largely driven by biology (in which I include psychology, which is also ultimately biology). This is something people dealing with mental illness discovered a long time ago – depression is “molecules in your brain” – well, so is obesity! Let me explain. Humans throughout evolutionary history, like all living creatures, were faced with a dilemma, namely to deal with wide variations in food availability over time (feast vs. famine). Biologically, this means that they were driven in times of plenty to take up and store as many calories as they could in preparation for bad times – this is how our ancestors survived to this day. While finding and eating food during times of plenty does not require much work or motivation, finding food during times of famine requires us to go to almost any length and risks to find food. This risk-taking behaviour is biologically ensured by tightly linking food intake to the hedonic reward system, which provides the strong intrinsic motivator to put in the work required to find foods and consume them beyond our immediate needs. Indeed, it is this link between food and pleasure that explains why we would go to such lengths to further enhance the reward from food by converting raw ingredients into often complex dishes involving hours of toiling in the kitchen. Human culinary creativity knows no limits – all in the service of enhancing pleasure. Thus, our bodies are perfectly geared towards these activities. When we don’t eat, a complex and powerful neurohormonal response takes over (aka hunger), till the urge becomes overwhelming and forces us to still our appetites by seeking, preparing and consuming foods – the hungrier we get, the more we seek and prepare foods to deliver even greater hedonic reward (fat, sugar, salt, spices). The tight biological link between eating and the reward system also explains why we so often eat in response to emotions – anxiety, depression, boredom, happiness, fear, loneliness, stress, can all make us eat. But eating is also engrained into our social behaviour (again largely driven by biology) – as we bond to our mothers through food, we bond to others through eating. Thus, eating has been part of virtually every celebration and social gathering for as long as anyone can remember. Food is celebration, bonding, culture, and identity – all… Read More »

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Arguments Against Obesity As A Disease #6: Stigmatizes People Living With Obesity

Continuing in my miniseries on arguments I often hear against calling obesity a disease, I will now deal with the issue of stigma and discrimination, namely that declaring obesity a disease stigmatizes people who may be healthy. I have already dealt with the issue of not using the terms “obesity” to describe people of size, who are perfectly healthy. Thus, using the actual WHO definition of obesity (the accumulation of excess or abnormal body fat that impairs health), this term should not used to describe people who do not experience health problems from their body fat. That said, how exactly does obesity stigmatize people who actually have obesity (using the above definition and not simply BMI)? No doubt, obesity is a highly stigmatised condition, but so are numerous other diseases including depression, addictions, HIV/AIDS and many others. While much has been achieved in destigmatizing these conditions, obesity still lags far behind. This problem cannot be addressed by refusing to call obesity a disease – it can only be addressed by getting people (including friends and family) to understand the complex and multi-factorial nature of this disorder and the rather limited treatment options that we currently have available for people living with this disease. It is not calling obesity a disease that promotes weight bias and stigma, rather, it is the fairy tale of “choice” and the overly simplistic “eat-less move-more” propaganda that stigmatises people living with excess weight by promoting discriminatory stereotypes and the notion that they are simply not smart or motivated enough to change their slovenly ways. In contrast, acknowledging that obesity is a disease with a complex psychosociobiology, if anything, can actually help move us towards destigmatising obesity in the same way that depression has been destigmatised by reframing the issue as a matter of “chemicals in the brain” (which incidentally would also apply  to most of obesity). Thus, not only should calling obesity a disease help reduce stigma but also hopefully go a long way in reducing wight-based discrimination in everything from access to care to disability legislation. @DrSharma New Orleans, LA

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