Overweight and Obesity

Overweight and obesity affect an increasing portion of the global population, significantly impacting health and quality of life. Here, we provide a comprehensive overview: definition of overweight, BMI classification, causes, consequences, and appropriate treatments. Stay informed to better understand the challenges and available solutions.

Definition of Overweight

Weight is assessed in relation to body surface area (approximated by the square of height). This defines a key parameter: the Body Mass Index (BMI).

BMI = Weight / height²

This parameter allows for the classification of an individual's weight based on a scale established by the NIH (National Institutes of Health, USA) in 1998:

Classification Body Mass Index (kg/m²)
Underweight < 18.5
Normal 18.5 - 24.9
Overweight 25 - 29.9
Obesity class I 30 - 34.9
Obesity class II 35 - 39.9
Severe obesity class III > 40

Epidemiology

Excess weight is steadily increasing worldwide. In 2014, 30% of the global population was overweight or obese, and this number is projected to reach 40% by 2030. In France, ObEpi surveys show a consistent rise in obesity prevalence, which doubled between 1997 and 2012.

Causes

Obesity results from an energy imbalance between intake and expenditure. This imbalance is influenced by:

  • Stomach volume
  • Hormones regulating hunger and satiety (leptin, ghrelin, insulin)
  • Central brain control, especially the hypothalamic centers for appetite

Consequences

Overweight can lead to chronic complications that reduce life expectancy, including:

Cardiovascular Complications

High blood pressure, heart attacks, strokes, thrombosis, and pulmonary embolisms are more common in obese individuals.

Metabolic Complications

Type 2 diabetes and dyslipidemia (high “bad” cholesterol levels) are frequent in those who are overweight.

Other Complications

  • Osteoarthritis in weight-bearing joints
  • Sleep apnea
  • Fatty liver disease (hepatic steatosis)
  • Hormone-related and digestive cancers

Risk Reduction After Weight Loss

Losing 10 kg leads to:

  • 25% reduction in overall mortality risk
  • 40% fewer deaths related to diabetes
  • 40% fewer obesity-related cancer deaths
  • Over 50% reduction in diabetes risk

Treatments for Overweight Individuals

Care typically includes:

  • Nutritional and psychological support
  • Regular physical activity (30 minutes per day, as recommended by HAS – French Health Authority)
  • For severe obesity (BMI > 40)bariatric surgery may be considered to promote lasting changes

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