How obesity impacts cardiovascular health
Written in association with:
Cardiologist
Published: 14/01/2025
Edited by: Jessica Wise
In this article, leading consultant cardiologist Dr Teresa Castiello explains the relationship between obesity and cardiovascular health.
What is obesity, and how do we define it?
‘Obesity’ is an uncomfortable word. It is often misunderstood and stigmatised or, conversely, underestimated in its primary value, which is medical.
Obesity is more than just a cosmetic concern and certainly has nothing to do with ‘body shaming’. Medical advice is not judgmental but aims to achieve both mental and physical health.
Obesity is a complex, chronic disease characterised by an excessive accumulation of body fat which poses significant health risks. While we may picture someone visibly overweight, it's important to remember that obesity is a spectrum.
To classify weight status, Body Mass Index (BMI), a calculation based on height and weight, is typically used. A BMI between 18.5 and <25 is considered a healthy body weight, between 25 and <30 falls within the overweight range; a BMI of 30 or higher generally falls within obesity, where 40 and over is severe obesity, with the highest health risk.
However, BMI alone does not take into account body composition, and failing to distinguish between muscle from fat or water content. It's also crucial to consider other factors like waist circumference, as fat concentrated around the abdomen is particularly harmful. In that regard, a body composition analysis, which measures the proportion of fat to muscle, can provide a more accurate assessment of an individual's health risks.
Why would cardiologists be concerned about obesity?
I will answer this question, sharing what the European Society of Cardiology, the largest cardiology society in the world, has recently declared about obesity:
Obesity is now a pandemic and has doubled since 1990 – almost 1 in 4 European adults (23%) living with obesity. 7% of total national budgets across the EU is spent on non-communicable diseases associated with obesity - a large proportion of this related to cardiovascular disease (CVD). People living with obesity have a 50%–100% increased risk of death from all causes compared to normal-weight individuals, and most of this increased risk - 67.5% - is due to CVD. Governments and healthcare systems have failed to effectively curb the obesity pandemic, leading to a significant increase in preventable deaths from CVD. Obesity is highly prevalent among patients with CVD and significantly impacts both the course and prognosis of the condition. It is essential for cardiologists to actively engage in the management of obesity as an integral part of comprehensive patient care. While non-pharmacological measures remain first course of action, new drugs have recently become available that can significantly lower body weight; some of these drugs have been shown to improve cardiovascular prognosis yet expense and availability is an issue in all countries. Beyond its recognition as a high-risk condition that is causally linked to multiple chronic illnesses, many medical societies and health professionals consider obesity as a disease itself, resulting in impaired quality of life and reduced life expectancy.
What are the main health risks associated with obesity?
Obesity is a serious public health concern with wide-ranging consequences for individuals and healthcare systems. It significantly elevates the risk of cardiovascular diseases, including coronary artery disease (leading to angina, heart attacks, and necessitating interventions like angioplasty or bypass surgery), heart failure, cardiomyopathy, stroke, high blood pressure, and abnormal heart rhythms.
Beyond its impact on the cardiovascular system, obesity disrupts metabolic processes, increasing the likelihood of developing type 2 diabetes and metabolic syndrome.
Furthermore, obesity is linked to an increased risk of certain cancers, including colon, breast, endometrial, and kidney cancer. It can also lead to liver disease with fat buildup in the liver, which can lead to liver damage and cirrhosis, and kidney disease. Pregnancy complications are also more common in obese individuals.
Obesity is also linked to sleep apnoea, a condition where breathing repeatedly stops and starts during sleep. The extra weight can put stress on your joints, contributing to osteoarthritis, a degenerative joint disease. And the impact extends beyond physical health; obesity can also take a toll on mental well-being, increasing the risk of depression and anxiety. The latter is also linked to low-grade but chronic inflammatory processes.
In essence, obesity acts as a catalyst for a multitude of health problems, compromising various bodily systems and overall quality of life. Recognising the seriousness of obesity and its far-reaching consequences is crucial for promoting effective prevention and management strategies.
What are the primary causes of obesity?
The word "obesity" has its etymological origins in "esum," the past participle of the verb "edere" (to eat), and "ob," a causal prefix (for, because of).
In short, the Latins attributed the cause of obesity to excessive eating. Which is true, but food is only one component of a much broader and more complex problem.
Obesity, a growing global health concern, arises from a complex interplay of factors that ultimately lead to an energy imbalance – where we take in more calories than we burn. While our individual susceptibility to weight gain is influenced by genes and biological processes, the alarming rise in obesity rates worldwide is largely fuelled by the environment we live in and the societal norms that shape our choices.
The modern food environment, with its abundance of inexpensive, highly processed foods laden with calories, unhealthy fats, and added sugars, encourages overconsumption and weight gain. Our increasingly sedentary lifestyles, characterised by limited physical activity and reliance on cars and public transport, further contribute to this energy imbalance by reducing calorie expenditure. Marketing and advertising also play a powerful role by influencing our dietary habits with persuasive campaigns for unhealthy food choices and sugary drinks. Moreover, urban environments often lack green spaces and recreational facilities, discouraging physical activity, while socioeconomic factors like poverty and food insecurity can limit access to healthy food options.
While environmental and societal factors are major drivers, our biology and genetics also contribute. Some individuals may be genetically predisposed to gain weight more easily or store fat in certain areas. Hormonal imbalances can disrupt appetite regulation and metabolism, making it harder to control weight. Even the composition of bacteria in our gut can influence how we process food and store energy. Sleep deprivation and certain medications can also tip the scales towards weight gain. Psychological factors, such as stress, emotional eating, and mental health conditions, further complicate the picture by influencing our eating habits and motivation for physical activity.
Addressing this complex issue requires a multi-pronged approach that tackles both individual behaviours and the broader environmental and societal influences that shape our choices.
What is the link between obesity and inflammation?
The link between obesity and inflammation is a crucial one to understand, as it underpins many of the health risks associated with excess weight. Essentially, obesity triggers a chronic, low-grade inflammatory state throughout the body, and this ongoing inflammation acts as a driving force behind various diseases, particularly cardiovascular disease.
Adipose tissue dysfunction: Fat tissue, also known as adipose tissue, isn't just a storage depot for excess calories. It's an active endocrine organ that releases hormones and signalling molecules. In obesity, fat cells become enlarged and dysfunctional. They start producing an excess of pro-inflammatory molecules (like cytokines) and reduce the production of anti-inflammatory ones. Immune system activation: This imbalance in signalling molecules triggers a chronic inflammatory response, with immune cells infiltrating the fat tissue. Macrophages, a type of immune cell, accumulate in the fat and release further inflammatory mediators. Systemic inflammation: This inflammation isn't confined to fat tissue. It spills over into the bloodstream, affecting other organs and systems throughout the body. This chronic, low-grade inflammation contributes to the development of insulin resistance, leading to type 2 diabetes; atherosclerosis, plaque buildup in the arteries, increasing the risk of heart attack and stroke, endothelial dysfunction (impaired function of the blood vessel lining, contributing to high blood pressure and blood clots) and heart failure.Inflammation and obesity become intertwined in a vicious cycle. Inflammation can worsen insulin resistance, further promoting fat accumulation and weight gain. This, in turn, perpetuates the inflammatory state, creating a self-reinforcing loop.
What are the most effective ways to treat obesity?
Obesity is a complex health condition requiring a comprehensive and individualized approach to treatment.
Lifestyle interventions form the cornerstone of obesity treatment and should always be the first line of attack.
This includes dietary modification to create a sustainable calorie deficit, ideally 500-1000 kcal per day to allow for gradual and long-lasting weight loss, focusing on whole foods like fruits, vegetables, and lean protein while limiting processed foods, refined sugar, and saturated fats. The dietary styles with the strongest evidence for achieving and maintaining a healthy body weight are the Mediterranean diet, the DASH diet, and the low-carbohydrate diet. These 3 diets prioritize whole grains, fruits, and vegetables while limiting processed foods and added sugars. The Mediterranean diet emphasizes healthy fats like olive oil and fish, while the DASH diet focuses on low-fat dairy and limits sodium for blood pressure control. Low-carbohydrate diets restrict carbohydrates, leading to potential benefits for weight loss and blood sugar control, but long-term cardiovascular effects require further research.
Regular physical activity is also crucial, with at least 150 minutes of moderate-intensity exercise per week recommended, along with efforts to increase daily movement.
It is also important to work on a psychological level, given the well-known association between food and the emotional sphere, and often obesity is associated with emotional distress that can also lead to depression. Behavioural therapy, such as cognitive behavioural therapy (CBT) and mindful eating techniques, can help individuals identify and modify unhealthy thoughts and behaviours related to eating and exercise.
When should we consider a medical intervention to treat obesity and what are the options? We have all heard about 'semaglutide'...
It's important to emphasise that medical interventions should always be used in conjunction with lifestyle modifications and should never be considered a stand-alone therapy. We should not aim for immediate results, but for lasting ones with long-term effects. It's great if the drug facilitates and accelerates weight loss safely, but it should always be combined with a radical change in lifestyle.
However, for some individuals, medications can be a valuable complement to lifestyle changes. These are typically considered for people with a BMI ≥30 kg/m² or ≥27 kg/m² with obesity-related complications.
New drugs are now available, such as semaglutide and liraglutide, which act as GLP-1 receptor agonists. By mimicking a natural hormone, they regulate appetite and blood sugar levels, and are rapidly replacing pre-existing options (such as orlistat, which reduces fat absorption but has a modest effect and unknown data on cardiovascular outcomes).
In cases of severe obesity (BMI ≥40 kg/m² or ≥35 kg/m² with complications) where lifestyle changes and medication have not been effective, bariatric surgery may be an option. Common procedures include gastric bypass, sleeve gastrectomy, and adjustable gastric banding. These surgeries can lead to significant weight loss and improvement in obesity-related health issues. However, semaglutide can achieve weight loss comparable to surgery (20%) if combined with exercise and healthy nutrition.
Obesity management often involves a multidisciplinary team of healthcare professionals, including physicians, dieticians, psychologists, and exercise specialists, working together to provide comprehensive care. Ultimately, successful obesity management requires ongoing support and a long-term commitment to lifestyle changes.
Can we discuss in more detail the role of GLP-1 receptor agonists in treating obesity and reducing cardiovascular risk?
GLP-1 receptor agonists are a relatively new class of drugs that are showing great promise in the treatment of obesity and related conditions. Originally developed for type 2 diabetes, these medications have shown remarkable success in helping individuals achieve significant weight loss and improve their heart health. They mimic a natural hormone called GLP-1, which plays a key role in sugar metabolism and insulin secretion.
By activating GLP-1 receptors, these drugs help to decrease appetite, increase feelings of fullness, improve blood sugar control, and slow gastric emptying. This leads to reduced food intake, weight loss, and better blood sugar management.
Beyond their metabolic effects, GLP-1 receptor agonists also offer impressive cardiovascular benefits.
Currently, semaglutide, known by the brand names Ozempic and Wegovy, is the only weight loss intervention with proven outcomes in patients with cardiovascular disease and without diabetes. A major clinical trial called SELECT has shown that semaglutide not only helps people lose weight, but also significantly reduces the risk of heart attacks, strokes, and cardiovascular death in those who already have heart disease. It also has the added benefit of improving blood pressure, cholesterol levels, and blood sugar control. Another drug in this class, liraglutide (Saxenda, Victoza), has demonstrated a strong safety profile in cardiac patients, but is currently approved for patients with concomitant diabetes. Tirzepatide (Mounjaro), a new obesity drug that acts by mimicking two natural hormones (GLP1 and GIP), is also under study, but official data on cardiovascular effects are not yet published.
These new drugs offer a promising new approach to improving both metabolic and cardiovascular outcomes, addressing a critical need in the fight against obesity and its associated health consequences. However, we must be very careful not to convey the message of a ‘magic pill’ and a ‘one-fits-all solution’.
What are the risks and the side effects of this class of medications? Can any patient with obesity take them?
While generally safe and well-tolerated, GLP-1 receptor agonists, like all medications, can have potential side effects: the most common are gastrointestinal in nature , like nausea, vomiting, and diarrhoea, which usually subside over time. Less common but more serious side effects include pancreatitis and gallbladder problems.
It is crucial to emphasize that these drugs are not suitable for everyone and must be taken under strict medical supervision, exclusively for the indications for which they have been studied and approved.
These medications are contraindicated in individuals with a history of pancreatitis, type 1 diabetes, medullary thyroid carcinoma, or multiple endocrine neoplasia type 2 syndrome. They should also be avoided during pregnancy and breastfeeding.
Self-medication is strongly discouraged. A careful medical evaluation is essential to determine if the benefits outweigh the risks in each specific case.
What are some of the challenges in treating obesity?
Treating obesity can be challenging for several reasons. One of the biggest hurdles is weight regain after initial weight loss, especially if it's a sudden loss not associated with substantial lifestyle changes. Our bodies have a natural tendency to defend a certain weight, making it difficult to maintain weight loss in the long term. This is another reason why it's essential to talk about lifestyle and a holistic approach rather than just medications or diets. Moreover, in severely obese individuals, drastic weight loss, especially if not accompanied by physical exercise, leads to excess skin tissue, which may then require corrective plastic surgery.
Another challenge is the stigma associated with obesity. People with obesity often face discrimination and negative stereotypes, which can make it harder to seek help and make positive changes. The economic aspect should not be underestimated either: healthy foods are often more expensive than processed foods, making them less accessible to low-income families. Access to care can also be an obstacle, as not everyone has the same resources and support necessary for effective weight management
What can be done to prevent obesity at the individual and societal levels?
Preventing obesity requires a multi-pronged approach that addresses both individual behaviour and the environment in which we live. At the individual level, promoting healthy lifestyle habits from a young age is crucial. This includes encouraging healthy eating, regular physical activity, and adequate sleep. At the societal level, we need to create environments that support healthy choices. This could involve policies that promote access to healthy foods and safe places to be active, as well as regulations on the marketing of unhealthy foods. Addressing the root causes of obesity will require a collaborative effort from individuals, families, communities, and policymakers.
It is a serious condition, but treatable and reversible, and it needs to be addressed in a personal, collective, scientific, and empathetic way.
If you are experiencing chest pain and would like to consult with Dr Castiello, you can do so via her Top Doctors profile.