Introduction

Obesity has emerged as one of the most significant global public health challenges of the 21st century. According to the World Health Organization (WHO), more than 1.9 billion adults worldwide are overweight, and over 650 million are classified as obese. This means that nearly one-third of the global population carries excess body weight. Alarmingly, obesity is no longer limited to adults: 41 million children under the age of five and more than 340 million children and adolescents aged 5 to 19 are overweight or obese.

In Spain, the situation mirrors global trends. Approximately 53% of the adult population weighs more than recommended, while childhood obesity affects 14% of children, with an additional 12% classified as overweight. These figures underscore that obesity is not an isolated issue but a widespread chronic disease with serious health, social, and economic consequences.

Far from being a purely aesthetic concern, obesity is a complex, multifactorial medical condition associated with increased morbidity, premature mortality, and rising healthcare costs. Globally, obesity contributes to an estimated 2.8 million deaths per year, while in Spain alone, obesity-related treatments account for nearly 7% of total healthcare spending.

This article provides a comprehensive, research-based overview of obesity, covering its medical definition, root causes, associated health risks, and evidence-based management strategies. It also highlights available support and treatment resources for individuals seeking care, including localized options for residents of Milwaukee.

Medical Definitions: What Do Overweight and Obesity Mean?

Body Mass Index (BMI) as a Diagnostic Tool

Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. Clinically, these conditions are most commonly assessed using the Body Mass Index (BMI), a screening tool that relates a person’s weight to their height.

Weight (kg) ÷ Height² (m²)

BMI is calculated as:

The standard BMI classifications for adults are:

  • Underweight: BMI below 18.5

  • Normal weight: BMI 18.5–24.9

  • Overweight: BMI ≥ 25

  • Obesity (Class I): BMI 30–34.9

  • Obesity (Class II): BMI 35–39.9

  • Obesity (Class III): BMI ≥ 40

Limitations of BMI

While BMI is widely used in clinical and epidemiological settings, it has limitations. It does not distinguish between fat mass and muscle mass, nor does it account for fat distribution. For this reason, healthcare professionals may also consider waist circumference, body fat percentage, and metabolic markers when assessing obesity-related health risks.

Root Causes of Overweight and Obesity

Obesity does not result from a single cause. Instead, it develops through the interaction of biological, behavioral, environmental, and socioeconomic factors.

Genetic and Familial Factors

Research shows that genetics can account for 40–70% of an individual’s susceptibility to obesity. Certain genetic variations influence appetite regulation, fat storage, and energy expenditure. Additionally, family environments often reinforce shared dietary patterns and activity levels, further contributing to weight gain.

Hormonal and Metabolic Influences

Hormones play a critical role in body weight regulation. Conditions such as insulin resistance, leptin resistance, and imbalances in appetite-regulating hormones like ghrelin can promote excessive calorie intake and fat accumulation. Endocrine disorders, including hypothyroidism and polycystic ovary syndrome (PCOS), may also contribute to weight gain when left untreated.

Lifestyle and Behavioral Factors

Modern lifestyles have significantly altered eating and activity patterns. High consumption of ultra-processed, energy-dense foods, combined with low intake of fiber-rich fruits and vegetables, increases caloric intake. At the same time, sedentary behaviors—such as prolonged screen time and desk-based work—reduce daily energy expenditure.

Sleep deprivation, chronic stress, and smoking cessation are additional behavioral factors associated with weight gain.

Socioeconomic and Environmental Determinants

Environmental factors strongly influence obesity risk. Limited access to healthy foods, unsafe neighborhoods that discourage physical activity, and aggressive marketing of unhealthy products all contribute to rising obesity rates. Lower socioeconomic status is consistently associated with higher obesity prevalence, highlighting the role of social determinants of health.

Associated Health Risks of Obesity

Obesity is a major risk factor for numerous chronic diseases, affecting nearly every system in the body.

Cardiovascular Disease and Hypertension

Excess body fat increases blood volume and vascular resistance, forcing the heart to work harder. Over time, this can lead to high blood pressure, left ventricular hypertrophy, coronary artery disease, and an increased risk of heart attack and stroke.

Type 2 Diabetes

Obesity is the leading risk factor for type 2 diabetes mellitus, a metabolic disorder characterized by chronic hyperglycemia due to insulin resistance. Persistent high blood glucose levels can result in complications affecting the kidneys, eyes, nerves, and cardiovascular system.

Musculoskeletal Disorders

Excess weight places additional stress on joints, particularly the knees and hips, increasing the risk of osteoarthritis and chronic pain. Reduced mobility often further exacerbates weight gain.

Respiratory and Liver Conditions

Obesity is closely linked to obstructive sleep apnea, a condition marked by repeated breathing interruptions during sleep. It is also a primary driver of non-alcoholic fatty liver disease (NAFLD), which can progress to cirrhosis if untreated.

Cancer and Mental Health Effects

Scientific evidence associates obesity with increased risk of several cancers, including breast, colorectal, and endometrial cancer. Beyond physical illness, obesity can negatively affect mental health, contributing to depression, anxiety, low self-esteem, and social stigma.

Evidence-Based Treatment Options for Obesity

The management of obesity must be individualized, taking into account the patient’s BMI, comorbidities, and overall health status. Treatment is typically guided by a multidisciplinary healthcare team.

Lifestyle Interventions

The foundation of obesity treatment involves sustainable lifestyle changes. This includes adopting a balanced, calorie-appropriate diet, improving food quality, and increasing physical activity. International guidelines recommend at least 150–300 minutes of moderate physical activity per week for adults.

Behavioral therapy, nutritional counseling, and long-term support are essential for maintaining weight loss.

Medical Management

For individuals who do not achieve adequate results through lifestyle changes alone, prescription weight-loss medications may be considered. These medications work through various mechanisms, such as appetite suppression or improved glucose regulation, and must be prescribed and monitored by a qualified physician.

Surgical Treatment

In cases of severe obesity or obesity accompanied by serious comorbidities, bariatric surgery may be recommended. Procedures such as gastric bypass or sleeve gastrectomy can result in significant and sustained weight loss, as well as improvement in obesity-related diseases. However, surgery requires lifelong medical follow-up and adherence to nutritional guidelines.

Obesity Treatment and Support Resources in Milwaukee

For individuals living in Milwaukee, a range of professional resources is available to support obesity management. These include medical weight-loss clinics, bariatric surgery centers, registered dietitians, and community-based wellness programs. Local public health initiatives also promote nutrition education and physical activity to help reduce obesity rates at the population level.

Consulting with a primary care physician or endocrinologist is the first step toward accessing appropriate treatment and support.

Conclusion

Obesity is a chronic, relapsing disease driven by complex biological and environmental factors. Its impact extends far beyond appearance, significantly increasing the risk of chronic illness, mental health disorders, and premature death. Addressing obesity requires a comprehensive, evidence-based approach that combines prevention, early intervention, and personalized treatment.

Through informed medical care, lifestyle modification, and supportive health systems, individuals and communities can reduce the burden of obesity and improve long-term health outcomes.

Medical Disclaimer

This article is for informational purposes only and does not replace professional medical advice. Diagnosis and treatment of obesity should always be guided by a qualified healthcare professional.