Accurately measuring body fat directly can be challenging. However, the body mass index (BMI) serves as a simple ratio that provides an estimate of relative weight in relation to height and is significantly correlated with total body fat content. BMI is calculated by dividing weight in kilograms by height in meters squared. The World Health Organization (WHO) has categorized BMI into different classifications, including underweight, normal weight, overweight, and obesity, to help assess weight status and associated health risks.
For Adults:
In adults, the WHO defines overweight and obesity as follows:
- Overweight: BMI greater than or equal to 25
- Obesity: BMI greater than or equal to 30
For Children under 5 years of age:
For children under 5 years of age, the WHO uses weight-for-height measurements to determine overweight and obesity:
- Overweight: Weight-for-height greater than 2 standard deviations above the WHO Child Growth Standards median
- Obesity: Weight-for-height greater than 3 standard deviations above the WHO Child Growth Standards median
Causes of Obesity
Obesity can have multiple causes, with both genetic and behavioral factors playing significant roles. Here are some common causes of obesity:
- Genetic Factors: Certain genetic predispositions can contribute to obesity, making some individuals more susceptible to weight gain.
- Unhealthy Diet: Consuming a diet high in calories, saturated fats, sugar, and processed foods can lead to weight gain and obesity.
- Lack of Physical Activity: Sedentary lifestyles with minimal physical activity can result in an energy imbalance, where the calories consumed exceed the calories burned.
- Medications: Certain medications, such as antidepressants, antipsychotics, corticosteroids, and some hormonal medications, can cause weight gain as a side effect.
- Environmental Factors: Factors like easy access to unhealthy foods, food marketing, and sedentary environments can contribute to obesity.
- Age, Sex, and Ethnicity: Age-related changes in metabolism, hormonal factors, and differences in body composition can influence the risk of obesity. There may also be variations in obesity prevalence based on sex and ethnicity.
- Psychological Factors: Emotional eating, stress, and other psychological factors can lead to overeating and contribute to weight gain.
- Specific Medical Conditions: Certain medical conditions like hypothyroidism, polycystic ovary syndrome (PCOS), and hormonal imbalances can increase the risk of obesity.
Understanding these causes can help individuals make informed decisions about their lifestyle choices and seek appropriate interventions for weight management.