Obesity is a major international problem and the British are rapidly becoming amongst the heaviest people in the world. Obesity is associated with many medical problems, most of which improve with weight loss.

In no particular order, obesity increases the risk of the following:

• Type 2 diabetes mellitus
• Hypertension (high blood pressure)
• Reduced life expectancy
• Coronary heart disease
• Polycystic ovary syndrome
• Colon and prostate cancer in men
• Uterine and gallbladder cancer in women
• Gallstones
• Osteoarthritis
• Abnormal blood lipids
• Stroke
• Sleep apnoea
• Gout
• Fertility problems

For people suffering with obesity, weight loss then becomes of paramount importance. Since long-term weight loss is so difficult to achieve, particularly via dieting, it is important to have as much information and support from the start.

Nobody should embark on a weight loss programme without advice from a doctor or health professional - they can help you choose the most appropriate treatment for you, monitor your progress and provide you with appropriate advice and encouragement. Avon Obesity Service exists to help patients considering surgery.

Body Mass Index

Body mass index, or BMI, is the most common measure of an individual's weight relative to his or her height. The Body Mass Index (BMI) is a common measurement in evaluating overweight and obesity.

In scientific terms, BMI is the ratio of a person's weight to the square of their height (both in metric units). Your body weight is then categorised as follows:

• A BMI below 19.5 is classified as underweight
• A BMI between 19.5 and 25 is classified as normal/desirable
• A BMI between 25 and 30 is classified as overweight
• A BMI between 30 and 40 is classified as obese
• A BMI over 40, or over 35 and you have weight-related problems, is classified as morbidly obese