The Body Mass Index (BMI) is the standard way to measure whether someone is overweight or obese. It takes into account a person’s height and weight and generally is correlated with that individual’s excess body fat. There are some exceptions to this such as body builders or pregnant women.

BMI is calculated with the following formula:
Weight in kilograms divided by Height in meters squared (BMI = kg/m2)
So, for example
There are many BMI calculators on the internet such as this link from the Heart Foundation website

Obesity is associated with a large number of health problems including: high blood pressure, high cholesterol, diabetes or glucose intolerance, sleep apnoea, gastro-oesophageal reflux, arthritis or joint problems.

Many of these problems can be improved or sometimes completely eliminated with weight loss.

Diet and Lifestyle – there are many diet programs available which include combinations of low-fat and low-carbohydrate. They have some success in the short-term, but maintenance of weight loss in the longer-term can be difficult with this approach alone.

Bariatric surgery is the most effective treatment for obesity. It achieves long-term sustained weight loss, improvement in obesity-related illnesses, and reduces overall mortality.

There are three procedures which are most commonly performed:

Laparoscopic gastric sleeve
Laparoscopic roux-en-Y gastric bypass
Laparoscopic adjustable gastric band

These procedures work by a process of either restriction, malabsorption, or a combination of both.

Restriction is due to a reduction in the size of the stomach where food enters. The smaller stomach therefore fills up more quickly and leads to the sensation of feeling full after eating only a small amount of food.

Malabsorption is when the absorption of food (and therefore calories) by the gut is reduced, by re-plumbing the gut so that food bypasses a long segment of intestine.