Morbid Obesity
Are you a suitable candidate for Bariatric Surgery?

  • Over 1.3million people in the UK are considered morbidly obese and could be considered for bariatric surgery
  • Bariatric surgical procedures include laparoscopic gastric banding, laparoscopic gastric bypass, laparoscopic duodenal switch and laparoscopic sleeve gastrectomy
  • In classifying morbid obesity the Body Mass Index (BMI) is the most commonly used as a guide as to whether someone is obese. It is a ratio of weight and height (kg/m2)


        o BMI = weight (kg) ÷ height (m) ÷height (m)

        o For example, weight 126kg (19.5 stone), height 1.60m (5’4”),
          126kg ÷ 1.60m ÷1.60m = 49

BMI Calculator

Please enter your weight and height (in imperial or metric) in the boxes below, then press the "Calculate BMI" button

Weight  st  lb =  kg
Height  ft  in =  m
Your BMI = 0
[With thanks to Dr Ian Sidwell, Somerset Obesity Service]

BMI range

Weight class

Health risk

BMI 20-25

Normal weight 


BMI 25-30


Moderate health risk

BMI 30+

Clinically obese

High health risk

BMI 40+ 

Morbidly obese

Very high health risk

BMI 50+ 

Super obese

Extremely high health risk

  • A BMI over 40 is considered morbidly obese or a BMI over 35 along with other obesity related conditions such as those mentioned in table below
  • Another way to calculate being overweight is by your waist measurement. Risks increase with a waist measurement of over 40 inches (102cm) in men and over 35 inches (88cm) in women

Health risks associated with obesity

Greatly increased risk
Moderately increased risk
Slightly increased risk
Type 2 diabetes Heart disease Some cancers
Gallbladder disease Hypertension Reproductive abnormalities
Insulin resistance Osteoarthritis Polycystic Ovary Syndrome
Breathlessness Gout Impaired fertility
Sleep apnoea   Low back pain
High cholesterol   Anaesthetic complications

                                                                                                  (Department of Health 2006)

If you are thinking about bariatric surgery, calculate your BMI using the BMI calculator above, and see whether you fall into the morbidly obese category.

If you are eligible for surgery, then the next step is to consider the type of bariatric surgery that may be right for you, a laparoscopic gastric band, laparoscopic gastric bypass, laparoscopic duodenal switch or a laparoscopic sleeve gastrectomy. The majority of people choose to have either the laparoscopic gastric band or laparoscopic gastric bypass.