A scientific study led by Universidad Carlos III de Madrid (UC3M) and partly funded by the European Research Council (ERC) has determined that the size and composition of our social support networks directly influence how we perceive our body image. The findings could help us in treating conditions such as body dysmorphic disorder, anorexia, and other eating disorders.
Published in iScience, the study involved over 100 participants and used the “Footsteps Illusion,” an experiment in which the sounds of a person’s footsteps are modified in real time to simulate those of a lighter or heavier body. These auditory changes shift people’s perception of their own weight and trigger behavioral, emotional, and physiological variations, demonstrating how malleable body image is to sensory input.
Participants were asked to walk while listening to three types of footstep sounds: one unmodified, one with footsteps that sounded as if they were produced by a lighter body, and one with footsteps that sounded as if they were produced by a heavier body. In addition, participants answered questionnaires about their body image, possible symptoms of eating disorders, and the breadth of their social support networks.
The results of this experiment showed that people with larger and more diverse social networks were generally less influenced by the sound illusion and tended to be more satisfied with their body image and have fewer symptoms of eating disorders. Conversely, the modified effects of the steps were more intense in people with smaller social networks, leading to the conclusion that body perception and its malleability not only depend on immediate sensory stimuli but are also influenced by the social structure in which the person is integrated.
‘The implications of our study are that your circle of friends influences how you perceive your own body. If you have a wider circle of friends, you perceive your body in a more positive way,’ says Anxo Sánchez, a researcher in the Department of Mathematics at UC3M. ‘People would think that self-perception depends on oneself, but in reality it depends on the number of people who support you and surround you,’ explains another of the study’s authors, Amar D’Adamo, a researcher in the Department of Computer Science at UC3M.
These findings show that having broad and diverse social support reinforces the stability of body self-perception and protects against the influence of external signals that could distort it. This discovery, in turn, opens the door to new social interventions that serve to promote a more positive body image and mitigate the effects of weight-related stigma.
In addition, the team proposes the use of mobile applications to help people who may suffer from disorders associated with a negative self-perception of their own body: ‘At the i_mBODY Lab, we develop sensory technologies that allow us to change the perception of the body. We are also very focused on applications because we want to understand how we can use these technologies to support people,’ explains Ana Tajadura, head of the i_mBODY Lab, researcher at the Department of Computer Science at UC3M and ERC grantee.
Underweight patients may face higher risk of poor outcomes after surgery
Source: Pixabay CC0
Higher BMI is not linked to increased risk of death or other complications following shoulder replacement surgery, according to a new study by Epaminondas Markos Valsamis from the University of Oxford, UK, and colleagues publishing November 20th in the open-access journal PLOS Medicine.
Joint replacement surgeries – including hip, knee and shoulder replacements – can significantly improve quality of life. Many patients with obesity are denied these procedures despite a lack of formal recommendations from national organisations. Evidence on the risks of joint replacement surgery in patients with obesity is limited and mixed.
In this study, researchers analysed more than 20 000 elective shoulder replacement surgeries performed across the UK and Denmark to see whether BMI was associated with death or other complications.
Compared to patients with a healthy BMI (21.75 kg/m2), patients with obesity (BMI 40 kg/m2) had a 60% lower risk of death within the year following surgery. Those considered underweight (BMI <18.5 kg/m2) had a slightly higher risk of death. The study does not support restricting patients with a high BMI from having elective shoulder replacement surgery, contrary to evidence that some hospitals are starting to restrict patients.
One main limitation of this study was the small sample size of the underweight population (131 for the UK data, 70 for the Denmark data). However, this was a large study that consistently showed a lower risk of death and complications in patients with obesity undergoing shoulder replacement surgery across multiple outcomes and two countries. The results can help patients, surgeons, and policymakers make informed decisions about who should be considered fit for these surgeries.
Lead author Epaminondas Markos Valsamis says, “Shoulder replacements offer patients the opportunity for excellent pain relief and improved quality of life. Our research shows that patients with a higher BMI do not have poorer outcomes after shoulder replacement surgery.”
Senior author Professor Jonathan Rees adds, “While BMI thresholds have been used to limit access to joint replacement surgery, our findings do not support restricting higher BMI patients from accessing shoulder replacement surgery.”
The ratio of a person’s waist measurement compared to their height is more reliable than body mass index (BMI) at predicting heart disease risk, according to new research from UPMC and University of Pittsburgh physician-scientists.
This finding, published out now in The Lancet Regional Health—Americas, could reshape how clinicians and the public assess cardiovascular risk, especially for people who don’t meet the classic definition of obesity.
The team analysed data from 2721 adults who had participated in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). The individuals had no cardiovascular disease at baseline and were followed for more than five years.
“Higher BMI, waist circumference and waist-to-height ratio at baseline were all associated with higher risk of developing future cardiovascular disease – until we adjusted for other classic risk factors, such as age, sex, smoking, exercise, diabetes, hypertension and cholesterol,” said lead author Thiago Bosco Mendes, clinical instructor of medicine at Pitt and obesity medicine fellow at UPMC. “When we did that, only waist-to-height ratio held as a predictor.”
Much of that predictive power is concentrated among individuals with a BMI under 30, which is below the classic threshold for obesity, who may not realise they are at risk for cardiovascular disease.
BMI doesn’t account for fat distribution or distinguish between harmful, visceral fat and protective, subcutaneous fat. By contrast, waist-to-height ratio (WHtR), calculated by dividing waist circumference by height, directly reflects central obesity, which is more closely linked to heart disease. That means that people with a BMI lower than 30, but a WHtR over 0.5, may be at higher risk of future coronary artery calcification, a key marker of cardiovascular disease, even in the absence of other risk factors.
“Using waist-to-height ratio as a cardiovascular screening tool could lead to earlier identification and intervention for at-risk patients who might otherwise be missed,” said senior author Marcio Bittencourt, associate professor of medicine at Pitt and cardiologist at UPMC. “It’s a simple and powerful way to spot heart disease risk early, even if a patient’s weight, cholesterol and blood pressure all seem normal.”
Authors of a recent Lancet report argue that obesity should not just be seen as a risk factor for other diseases – but in some cases, should be seen as a disease itself. The position could change how we treat obesity globally. In the first of this two-part Spotlight series, we break down the debate around the issue, and its implications for health policy.
In 1990, just 2% of all young people around the world aged 5 to 24 were living with obesity. By 2021, this figure had more than tripled to over 6%. This is according to a recent study, which relied on Body Mass Index (BMI) data from 180 countries and territories around the world. It estimates that the rise in obesity among children and young people will only continue in the coming decades.
South Africa certainly isn’t immune to the crisis. A survey conducted in 2021/2022 found that 16% of all children aged 6 to 18 were “severely overweight”. Meanwhile, World Health Organization (WHO) data suggests that about 30% of all adults in South Africa are living with obesity, meaning a BMI of over 30, which is almost double the global level.
BMI, which simply looks at a person’s weight in relation to their height, is a crude measure of obesity. For instance, a person may have a high BMI simply because they have a lot of muscle rather than fat. But while it is agreed that BMI is a flawed indicator at the individual level, many experts recommend using it as a rough proxy for “health risk at a population level”.
For instance, a study which collected data on nearly three million people found that those who had very high BMI levels were, on average, more likely to die at an early age. The study also found that this was true of people with very low BMI levels (those who were underweight). In this context, the above figures paint a concerning picture.
Given the rising rates, experts argue that we need health systems to be able to track and respond to obesity urgently. But, according to a Lancet Commission published in January, health systems around the world may struggle to do this, because of a failure to accurately conceptualise and measure what obesity actually is.
The Lancet commission was developed by 58 experts from different medical specialties and though it has been the subject of debate, it has since been widely endorsed as a new way to understand obesity. Spotlight takes a look at what it concluded.
Delaying treatment for no reason
Obesity is often regarded as a risk factor for other diseases, for instance, type 2 diabetes. But according to the commission, there are certain cases in which obesity is not just a risk factor, but a disease itself – one that should be immediately treated.
One of the reasons for this is that obesity not only contributes to the emergence of other conditions but sometimes leads to clinical symptoms directly. For example, the cartilage that protects the joints in a person’s knees can sometimes become eroded when adults carry too much weight. In this case, a person could suffer from joint pain, stiffness and reduced mobility where obesity is clearly the cause.
Take another example. If fat deposits build up in the abdomen, this may limit how much the lungs can expand, causing breathlessness. Similarly, a build-up of fat around the neck can narrow a person’s upper airways, which can cause sleep apnoea.
Thus, obesity is not simply something which increases the risk of developing a separate disease in the future – but something which can directly (and presently) affect the functioning of organs.
More broadly, the commission argues that by hindering a person’s “mobility, balance and range of motion” obesity can in certain cases “restrict routine activities of daily living”. In these instances, obesity is a disease by definition, according to the commission. This is given that it defines disease as a “harmful deviation from the normal structural or functional state of an organism, associated with specific signs and symptoms and limitations of daily activities”.
But why does this conceptual debate matter?
Because at present, people often have to wait for other diseases to crop up before insurers or public health systems cover them for weight loss drugs or bariatric surgery – a procedure to help with weight loss and improve obesity-related health conditions. And when they do cover these services, it is often only after severe delay. Because obesity is only considered to be a risk factor, it isn’t typically treated with the same urgency as life-threatening diseases, according to the authors of the commission.
Professor Frances Rubino, the lead author of the commission, details how this problem manifests in the healthcare system.
“I’ve been doing bariatric surgery for 25 years in four different countries; in America, Italy, France and the UK,” he tells Spotlight, “In all of those countries, to meet the criteria for surgery people very often have to undergo six to 12 months of weight monitoring before their surgery is covered. So systematically you delay treatment”.
He continues: “Someone who has clinical obesity and has heart failure as a result of it is waiting for a year for what reason? That condition will only worsen and if the patient is still alive, the treatment [is] going to cost the same amount to the payer but it’s going to be less effective.”
Can’t people just diet?
One of the reasons that some academics have historically been reluctant to classify obesity as a disease is because of a fear that this may reduce people’s agency – instead of taking proactive steps to diet and exercise, people with obesity may simply view themselves as afflicted by a disease.
The belief that people with obesity can simply diet their way out of their situation is in fact partially why Rubino’s patients were forced to wait long periods of time before receiving bariatric surgery.
Rubino explains: “In America, many private payers [i.e. medical insurance schemes] have required weight monitoring programmes, where patients do nothing else other than see a dietician for 12 months, and if they skip one appointment, they have to start all over again. I think that in some cases, this has been misguided by the idea that you want to see if obesity can be reversed by somebody going on a diet.”
This, according to him, is a “misconception”, arguing that if someone faces such severe levels of obesity that they require surgery, diet is unlikely to offer a solution.
Indeed, research has shown that it’s very rare for people with obesity to lose large amounts of weight quickly without surgery or medication. For instance, a study on over 176 000 patients in the UK found that among men with “simply obesity” or a BMI of 30-34.9, only 1 in 210 were able to achieve a “normal” weight level within a year. Among men with morbid obesity or BMI of 35 or more, the chance was less than 1 than in 1000. Chances for women were roughly twice as good as men’s – so still exceedingly small.
Thus, if someone is severely obese and their excess weight is causing life-threatening symptoms, putting them on a diet for a year is unlikely to result in the urgent changes that may be required for them to get better. In fact, Rubino argues that they may simply die of their condition in the interim.
Taking a medical approach more quickly is easier now than ever before due to the regulatory approval of GLP-1 agonists like semaglutide and tirzepatide – Spotlight previously reported on the availability of these new diabetes and weight loss medicines in South Africa. An article by WHO officials from December states that because of the approval of these medicines “[h]ealth systems across the globe now may be able to offer a treatment response integrated with lifestyle changes that opens the possibility of an end to the obesity pandemic”.
Not all people with obesity are ill
There is a more scientific argument against categorising obesity as a disease. This is that while obesity can sometimes result in the negative health symptoms discussed above (like respiratory issues or reduced mobility) it doesn’t always do this.
In fact, the commission acknowledges that some people with obesity “appear to be able to live a relatively healthy life for many years, or even a lifetime”. One of the reasons for this is that excess fat may be stored in areas that don’t surround vital organs. For instance, if fat is stored in the limbs, hips, or buttocks, then this may cause less harm than if it is stored in the stomach.
Since obesity doesn’t always cause health problems, it isn’t always a disease. In order to deal with this conceptual hurdle, the commission classifies obesity into two categories – clinical and preclinical obesity.
If a person has pre-clinical obesity, this means they have a lot of excess fat, but no obvious health problems that have emerged as a result. In this case, obesity is not classified as a disease, though it may still increase the chance of future health problems (depending on a range of factors, like family history).
For a person to have clinical obesity, they must have a lot of excess fat as well as health problems that have already been directly caused by this. It is this that the commission defines as a disease.
This classification system, according to Rubino, ensures not only that we urgently treat people living with clinical obesity, but also that we don’t overtreat people – since if a person falls into the pre-clinically obese group, then they may not need treatment.
But if we’re going to treat clinical obesity as a disease, we’ll need clear methods of diagnosing people. Since BMI is deeply flawed and provides little information about whether a person is ill at the individual level, health systems will need something else. In part 2 of this Spotlight special series, we’ll discuss the options offered by the commission, and how this all relates to the situation in South Africa.
Risk of mortality during cancer treatment in relation to BMI. For non-small cell lung cancer treatment, immunotherapy seems to pose less risk for persons under a certain BMI, while conventional chemotherapy appears optimal for persons who might be overweight or obese. Credit: Osaka Metropolitan University
While being overweight increases the risk of developing lifestyle-related diseases, there is a phenomenon known as the obesity paradox where a decreased risk of death has been seen during cancer therapy. However, that paradox might not hold true for all cancer therapies, an Osaka Metropolitan University team reports in JAMA Network Open, a publication of the American Medical Association.
Led by graduate student Mr Yasutaka Ihara and Professor Ayumi Shintani of the Graduate School of Medicine’s Department of Medical Statistics, the team used a Japanese administrative claims database of more than 500 000 lung cancer patients and examined the relation between body mass index (BMI) and the risk of mortality during immunotherapy and conventional chemotherapy.
Focusing only on patients with advanced non-small cell lung cancer, the team found that the higher the BMI, the lower the risk of mortality when undergoing both immunotherapy and chemotherapy, though it does a U-turn around a BMI of 24. Patients with a BMI under 28 showed lower risk of mortality when undergoing immunotherapy compared to conventional chemotherapy, but for those at or over that figure, the risk increases with immunotherapy while it continues to get lower with chemotherapy.
“Immunotherapy might not always be the optimal treatment method for obese patients with advanced non-small cell lung cancer, so the use of conventional chemotherapy should also be considered,” Mr. Ihara stated. “In addition to BMI, age, hormones, and gut microbiota have been reported as factors that influence the effectiveness of immunotherapy. Evaluation of whether immunotherapy or conventional chemotherapy improves survival in the presence of these factors is expected to contribute to the development of precision medicine.”
In a study published in Arthritis & Rheumatology, people with hand osteoarthritis, higher body mass index was associated with greater pain severity in the hands, feet, knees, and hips.
Osteoarthritis is one of the most debilitating joint disorders worldwide, affecting up to 10% of men and 13% of women. Osteoarthritis is characterised by a progressive onset of joint damage, commonly associated with pain. Joints commonly affected include the knee, hip and hand. Various stressors, risk factors and genetics may predispose an individual to developing osteoarthritis in a particular joint.
In a study of 281 patients, researchers noted that observed associations of body mass index with hand pain and total body joint pain seemed to involve certain inflammatory markers (leptin and high-sensitivity C-reactive protein, respectively).
The researchers suggest that systemic effects of obesity, measured by leptin, could have a larger mediating role for pain in hands than in lower extremities. Low-grade inflammation, measured by hs-CRP, may contribute to generalised pain in overweight or obese individuals.
“Our results highlight the complexity of pain in hand osteoarthritis. Obesity is not only leading to pain through increased loading of joints in the lower extremities, but seems to have systemic effects leading to pain in the hands and overall body,” said lead author Marthe Gløersen, MD, of Diakonhjemmet Hospital, in Norway.
