Obesity

Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. A crude population measure of obesity is the body mass index (BMI), a person’s weight (in kilograms) divided by the square of his or her height (in metres). A person with a BMI of 30 or more is generally considered obese. A person with a BMI equal to or more than 25 is considered overweight.

Overweight and obesity are major risk factors for a number of chronic diseases, including diabetes, cardiovascular diseases and cancer. Once considered a problem only in high income countries, overweight and obesity are now dramatically on the rise in low- and middle-income countries, particularly in urban settings.

What causes obesity and overweight?

The fundamental cause of obesity and overweight is an energy imbalance between calories consumed and calories expended. Globally, there has been:

• an increased intake of energy-dense foods that are high in fat; and 
• an increase in physical inactivity due to the increasingly sedentary nature of many forms of work, changing modes of transportation, and increasing urbanization. 

Changes in dietary and physical activity patterns are often the result of environmental and societal changes associated with development and lack of supportive policies in sectors such as health, agriculture, transport, urban planning, environment, food processing, distribution, marketing and education.

What are common health consequences of overweight and obesity?

Raised BMI is a major risk factor for noncommunicable diseases such as:

• cardiovascular diseases (mainly heart disease and stroke), which were the leading cause of death in 2012;
• diabetes; 
• musculoskeletal disorders (especially osteoarthritis - a highly disabling degenerative disease of the joints); 
• some cancers (endometrial, breast, and colon).

The risk for these noncommunicable diseases increases, with an increase in BMI. 

Childhood obesity is associated with a higher chance of obesity, premature death and disability in adulthood. But in addition to increased future risks, obese children experience breathing difficulties, increased risk of fractures, hypertension, early markers of cardiovascular disease, insulin resistance and psychological effects. 

How can overweight and obesity be reduced?

Overweight and obesity, as well as their related noncommunicable diseases, are largely preventable. Supportive environments and communities are fundamental in shaping people’s choices, making the healthier choice of foods and regular physical activity the easiest choice (accessible, available and affordable), and therefore preventing obesity.

At the individual level, people can:

• limit energy intake from total fats and sugars; 
• increase consumption of fruit and vegetables, as well as legumes, whole grains and nuts;
• engage in regular physical activity (60 minutes a day for children and 150 minutes per week for adults). 

Individual responsibility can only have its full effect where people have access to a healthy lifestyle. Therefore, at the societal level it is important to: 

• support individuals in following the recommendations above, through sustained political commitment and the collaboration of many public and private stakeholders; 
• make regular physical activity and healthier dietary choices available, affordable and easily accessible to all - especially the poorest individuals. 

The food industry can play a significant role in promoting healthy diets by: 

• reducing the fat, sugar and salt content of processed foods; 
• ensuring that healthy and nutritious choices are available and affordable to all consumers; 
• practicing responsible marketing especially those aimed at children and teenagers; 
• ensuring the availability of healthy food choices and supporting regular physical activity practice in the workplace.

source: who.int