A healthy weight range for adults is commonly determined by body mass index (BMI), a calculation involving an individual’s weight and height. A healthy BMI is considered to be between 20 and 25. A person with a BMI of 25 or more is considered overweight, while a BMI of 30 or more is considered obese.
Obesity is typically caused by an imbalance between the energy taken in through food and the energy burned off through physical activity, ie, eating too much and moving too little. The body needs a certain amount of energy to function, but in an unhealthy lifestyle where more energy than needed is taken in, the surplus energy will be turned into fat.
Some medical conditions, such as an underactive thyroid gland (hypothyroidism) and Cushing’s syndrome, can also cause obesity.
How is BMI calculated?
BMI is calculated by dividing a person’s weight (in kilograms) by the square of their height (in metres), ie, kg/m2. While BMI is a useful measurement for most adults, it is only an estimate and does not take into account age, ethnicity or gender, or differentiate between body fat and muscle mass. BMI should be considered alongside waist circumference (which helps to assess risk by measuring the amount of fat carried around an individual’s middle) and other risk factors.
How being overweight affects your heart health
Obesity and being overweight is a risk factor for various health conditions, such as heart and cardiovascular conditions like stroke, type 2 diabetes, atrial fibrillation, high blood pressure, certain types of cancer, fatty liver disease, kidney disease, sleep apnoea and osteoarthritis.
A person’s quality of life may also be impacted through obesity stigma. This stigma has been associated with increased depression, anxiety and social isolation.2
Risk factors of obesity
Contributing factors: genetics, diet and lifestyle choices
A range of factors can contribute to being overweight or obese.
- Taking in more energy through food than is used by the body
- Lack of physical activity
- A sedentary lifestyle that includes a large amount of sitting during the day, even if an individual is physically active.
Other factors that can contribute include:
- Genetic factors such as parental overweight or obesity
- Birth factors such as maternal smoking and poor nutrition
- Socioeconomic factors such as having lower levels of education and income.
Positive lifestyle changes
Regular exercise and maintaining a healthy eating plan can help manage the risk of being overweight or obese. HRI has plenty of heart-healthy recipes for inspiration, as well as advice on nutrition and tips for leading a healthy lifestyle.
House of Commons Library, Obesity Statistics. Number 3336, 6 August 2019. https://commonslibrary.parliament.uk/research-briefings/sn03336/
- World Health Organization. Weight bias and obesity stigma. www.euro.who.int/__data/assets/pdf_file/0017/351026/WeightBias.pdf