Obesity: causes, danger, treatment options

Medically reviewed: 15, February 2024

Key takeaways

Obesity has emerged as a significant global health concern, posing numerous risks to affected individuals and straining healthcare systems worldwide. Here are three essential takeaways on obesity from a medical perspective:

1. Excessive weight gain increases the risk of developing various chronic diseases and conditions, such as type 2 diabetes, cardiovascular disease (including hypertension and stroke), sleep apnea, non-alcoholic fatty liver disease, osteoarthritis, and certain types of cancer (e.g., breast, colon, endometrial). Moreover, mental health issues, including depression and anxiety, often accompany obesity due to societal stigma and reduced quality of life. Recognizing these potential complications underscores the importance of addressing obesity promptly and effectively.
2. While overconsumption of calories relative to energy expenditure plays a crucial role in obesity development, other contributing factors must be considered when devising prevention and treatment strategies. Genetic predisposition, epigenetic modifications, sedentary behavior, poor diet quality, sleep disturbances, stress, medication use, and environmental influences collectively shape an individual’s likelihood of becoming obese or remaining overweight. Acknowledging this complexity allows healthcare providers to adopt personalized approaches catering to each person’s unique circumstances.
3. Comprehensive obesity management entails implementing evidence-based lifestyle modifications centered on balanced nutrition, regular physical activity, adequate sleep, and stress reduction techniques. In some cases, pharmacotherapy or bariatric surgery may also prove beneficial in achieving substantial weight loss and reducing comorbidities. Crucially, healthcare professionals should foster supportive relationships with patients, encouraging sustained adherence to healthy behaviors and promoting self-efficacy. Furthermore, community-level initiatives targeting education, policy changes, and built environment transformations hold immense promise for combatting obesity epidemics across populations. By integrating multidimensional interventions at both individual and collective levels, meaningful progress toward reversing obesity trends remains attainable.

What is obesity?

Obesity is a heavy accumulation of fat in the body’s fat cells to such a serious degree that it rapidly increases the risk of obesity-associated diseases and mortality. The fat may be equally distributed on the body, on the stomach (apple-shaped) or on the hips and thighs (pear-shaped).

Obesity represents a pressing public health challenge that continues to escalate globally, imposing considerable burdens on affected individuals and healthcare systems alike. Defined as excessive accumulation of body fat, obesity significantly elevates the risk of developing various chronic diseases and diminishes overall quality of life. This introductory chapter aims to provide a thorough understanding of obesity, elucidating its causes, implications, and available therapeutic options.

An excellent method to measure obesity and overweight is the Body Mass Index (BMI). It is calculated as your weight (in kg) divided by your height (in metres) squared. People of average weight are considered to have a BMI between 18.5 and 25 (kg/m2), and people with a BMI of 25 to 30 (kg/m2) are considered overweight, while people with a BMI of over 30 (kg/m2) are considered obese. Test your BMI here.

How common is obesity?

Obesity is found a little more among men than women. Stomach obesity is more frequent and occurs in 30 per cent of adult men and, to a lesser degree, in adult women. Obesity and stomach obesity are rapidly increasing, especially in young people. The occurrence of obesity has increased by five fold since the Second World War.

What are the serious obesity-related diseases?

Most importantly, being overweight and obese may cause several psychological problems like a feeling of inferiority, often caused by discrimination. Furthermore, many physical problems are related to obesity, like difficulties in breathing, personal hygiene, pain in the knees and back and skin problems.

People suffering from obesity more frequently have high blood pressure and diseases related to hardening of the arteries, with blood clots in the heart and the brain.

Excessive adiposity precipitates a cascade of deleterious physiologic processes culminating in increased morbidity and mortality rates among obese individuals. Notably, obesity substantially raises the incidence of:

1. Type 2 diabetes mellitus: Insulin resistance and pancreatic beta-cell dysfunction ensue, necessitating rigorous glycemic control to prevent micro-and macrovascular complications.
2. Cardiovascular disease: Hypertension, hyperlipidemia, coronary artery disease, heart failure, and thromboembolic events frequently afflict obese patients due to vascular remodeling, altered lipid profiles, and proinflammatory milieus.
3. Respiratory disorders: Obstructive sleep apnea, asthma, and pulmonary hypertension arise from mechanical constraints imposed by excess adipose tissue, compromised lung function, and low-grade systemic inflammation.
4. Non-alcoholic fatty liver disease: Hepatic steatosis develops in response to ectopic fat storage, oxidative stress, and hepatocellular injury, potentially progressing to cirrhosis and liver failure if left untreated.
5. Osteoarthritis: Joint degeneration occurs secondary to biomechanical strain, synovitis, and chondrocyte damage, particularly affecting load-bearing regions like knees and hips.
6. Cancer: Increased cellular turnover, chronic inflammation, and hormonal perturbations instigate carcinogenesis, primarily involving reproductive organs, gastrointestinal tract, and thyroid gland.

What causes obesity?

Obesity can be hereditary, hence some people are at increased risk. However, obesity only develops from overeating, irregular meals and lack of daily physical activity. Many people think that when a disease is hereditary, it is inevitable that you will suffer from the condition but this is not true.

The development of obesity arises from an intricate interplay among genetic, epigenetic, behavioral, and environmental factors. Although caloric intake exceeding energy expenditure constitutes a primary driver of weight gain, several additional elements contribute to obesity etiology:

• Genetics: Certain inherited gene variants increase susceptibility to obesity by influencing appetite regulation, metabolism, and fat distribution. However, genetics alone does not account for the rapid rise in obesity prevalence; rather, they interact with environmental stimuli to modulate body composition.
• Epigenetics: Environmental exposures, such as maternal nutrition during pregnancy, early childhood experiences, and sedentary behaviors, can induce persistent alterations in gene expression patterns, thereby augmenting obesity risk.
• Sedentary behavior: Modern societies increasingly embrace sedentary lifestyles characterized by prolonged sitting and insufficient physical activity, which adversely affect energy balance and promote weight gain.
• Diet quality: Consumption of nutrient-poor diets high in refined carbohydrates, saturated fats, and added sugars contributes to positive energy balance while simultaneously increasing inflammation and oxidative stress, further exacerbating obesity-related complications.
• Sleep disturbances: Chronic disruptions in sleep duration and circadian rhythms impair hormonal homeostasis, resulting in increased hunger, decreased satiety, and heightened propensity for weight gain.
• Stress: Psychological stressors activate neuroendocrine pathways that enhance visceral adiposity, insulin resistance, and systemic inflammation, fostering obesogenic environments conducive to weight gain.
• Medications: Several commonly prescribed medications, including antidepressants, antihistamines, corticosteroids, and anticonvulsants, can engender weight gain as secondary effects.
• Environment: Built environments lacking access to affordable, nutritious food options and safe recreational spaces perpetuate unhealthy eating habits and sedentary behaviors, fueling obesity epidemics.

If the people in Europe had grown up in China with plenty of non-fat foods and hard daily work in the rice fields, only a few of them would be overweight or fat. It is lifestyle which determines how the genes develop. The fact that the existence of obesity has increased by five times since the Second World War, is hardly due to a change of our genes. On the contrary, our lifestyles have changed rapidly.

Besides genes, food and physical activity, it is possible that other so far unknown elements may play a part.

When is obesity dangerous?

With a BMI of more than 25, it is advisable to change lifestyles and lose weight, especially if it is stomach obesity (apple-shaped). The waist circumference may be used in order to determine if you are apple-shaped.

Men with a waist circumference of more than 94cm (37in) and women with a waist of more than 80cm (31.5in) should not further increase their weight. An increased risk of obesity-related diseases is present with a waist circumference of more than 102cm (40in) for men and more than 88cm (34.6in) for women.

If your BMI is more than 30, it is required that you lose weight.

How is obesity treated?

A weight loss of 5 or 10kg among obese patients has a very positive effect on the risk of heart and blood-vessel diseases. The weight loss will not only reduce blood pressure and blood-cholesterol, but also have a beneficial impact on obesity-related diseases.

The help of a dietitian can result in weight-loss of 5 to 10kg in more than 90 per cent of patients put on regular diets of, for instance, 1500 to 2000 kilo calories per day, based on calorie-counting. Another option to attain the same result involves changing to an unlimited consumption of low-fat foods.

After losing weight, thorough guidance on shopping and preparation of foods with a fat-energy-percentage of 20 to 25 per cent is of paramount importance, in order to stop the weight being put back on.

Furthermore, it is important to increase daily physical activity. Patients, who do not reach a satisfactory weight-loss on a diet, may be subjected to medical or surgical treatment.

When is medical treatment necessary?

Obviously, not everybody needs medical treatment. If an obese patient loses weight by diet and exercise, there is no need for such treatment. Furthermore, many people do not want to have medical treatment

The main problem is to limit the treatment to persons who actually need it such as:

• those with a BMI of more than 30kg/m2 who have not reduced weight by diet changes, exercise or lifestyle changes.
• those with BMI of more than 28kg/m2 and the presence of risk elements or complications.
• those with BMI of more than 28kg/m2 who have experienced a previous rapid increase of weight.

Medication for obesity is not yet recommended for children as we have no knowledge of possible negative effects on puberty and later eating behavior.

How to maintain your weight after weight loss?

Weight loss is obtained most effectively by diets provided by professionals. However, by far the greater challenge is achieving a way of life that maintains the weight and reduces the chances of putting it back on.

Obesity is a disease that you cannot expect to be cured of or be under clinical control within a few weeks or months. Thus, short-term treatment with medicines should be rare.

Medical treatment must be expected to be necessary for years, possibly your whole life, in order to maintain the weight-loss and reduce illness. However, there is a lack of experience in medical treatment of obese patients for more than two years.

The information concerning efficiency and safety of medicines used in combination with other medicines is very limited.

Until we obtain more knowledge, medical treatment should be reserved for patients with high risk of complications, or patients who already have complications, for whom it is very important to maintain their weight.

Medical treatment of obesity

Medications for obesity treatment contribute to weight loss and increase the number of patients who achieve a weight loss of more than 5 or 10 kg. After the weight loss has been completed, the medicine helps prevent the patient from regaining the weight.

Medicines that reduce appetite help the patient eat less and stick to their diet. They work even without dieting but the loss is larger when there is a combination of the two. This is possibly due to an increased feeling of fullness and the reduction in hunger pangs because of the medication.

Some appetite-reducing medications increase the burning of calories, which intensifies the appetite reducing effect.

Another type of medication reduces the fat absorption from the bowels. It is only active in the bowels and, therefore, doesn’t have the typical side effects frequently seen for appetite-reducing medications. For efficient diets, where patients with a BMI above 35kg/m2 achieve a weight loss of about 15 kg within a period of six months, appetite reducing medications and other medicines to treat obesity may contribute to an extra weight loss of 3 to 6kg.

Medication should only be used in a treatment program including diet, exercise and lifestyle changes.