Key Facts:

According to World health Organization (WHO)-

  • Worldwide obesity has nearly tripled since 1975.
  • In 2016, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 650 million were obese.
  • 39% of adults aged 18 years and over were overweight in 2016, and 13% were obese.
  • Most of the world’s population lives in countries where overweight and obesity kills more people than underweight.
  • 41 million children under the age of 5 were overweight or obese in 2016.
  • Over 340 million children and adolescents aged 5-19 were overweight or obese in 2016.
  • Tenfold increase in childhood and adolescent obesity in four decades: as per a new study by Imperial College London and WHO
  • Obesity is preventable!!

Overweight and obesity

These are defined as abnormal or excessive fat accumulation that may impair health.

Body Surface Area (BSA)

In physiology and medicine, the body surface area (BSA) is the measured or calculated surface area of a human body. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass.

Body surface area (BSA) plays a key role in several medical fields, including cancer chemotherapy, transplantology, burn treatment and toxicology. BSA is often a major factor in the determination of the course of treatment and drug dosage.

A number of different formulas have been developed over the years to calculate the body surface area and they give slightly different results. The most commonly used formula now is that of Mosteller, published in 1987 in The New England Journal of Medicine.

BSA(m²)=+(√Height(cm) * weight(kg))%60

Other influential factors include the age and gender of the individual. The average adult BSA is 1.7 m² (1.9 m² for adult males and 1.6 m² for adult females). This number is used to calculate dosages for cytotoxic anticancer agents.

BSA is also used to provide more precise measures of hemodynamic parameters such as cardiac index (CI = cardiac output divided by BSA), stroke volume index (SVI = stroke volume divided by BSA), systemic vascular resistance index (SVRI = systemic vascular resistance divided by BSA) and pulmonary vascular resistance index (PVRI = pulmonary vascular resistance divided by BSA). In addition, BSA is used to adjust creatinine clearance when comparing it with normal values to assess for the presence and severity of kidney disease.

Basal metabolic Rate (BMR):

Basal metabolic rate (BMR) is the total number of calories that your body needs to perform basic, life-sustaining functions. These basal functions include circulation, breathing, cell production, nutrient processing, protein synthesis, and ion transport.

In 1926, Raymond Pearl, American biologist, regarded as one of the founders of biogerontology, proposed that longevity varies inversely with basal metabolic rate (the “rate of living hypothesis”). Support for this hypothesis comes from the fact that mammals with larger body size have longer maximum life spans (large animals do have higher total metabolic rates, but the metabolic rate at the cellular level is much lower, and the breathing rate and heartbeat are slower in larger animals).

According to Harris-Benedict equation BMR for men can be calculated as-

BMR(cal % day)=66.5+((13.5*weight(kg))%1 + ((5.003*Height(cm))%1 – (6.755 * Age(years)%1)

To lose weight, it is helpful to calculate the BMR. It can either be found using a formula designed by scientists, or you can get it tested in a lab, or you can use an online calculator. No method is perfectly accurate, but a lab test will probably give you the best estimate.

Body mass index (BMI)

It is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults. It is defined as a person’s weight in kilograms divided by the square of his height in meters (kg/m2).

BMI=Weight(kg) % Height(cm)²

For adults, WHO defines overweight and obesity as follows-

  • Overweight is a BMI greater than or equal to 25
  • Obesity is a BMI greater than or equal to 30

BMI provides the most useful population-level measure of overweight and obesity as it is the same for both sexes and for all ages of adults. However, it should be considered a rough guide because it may not correspond to the same degree of fatness in different individuals.

Raised BMI is a major risk factor for non-communicable 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 (including endometrial, breast, ovarian, prostate, liver, gallbladder, kidney, and colon).

The risk for these non-communicable diseases increases, with increases 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, and early markers of cardiovascular disease, insulin resistance and psychological effects.