Weight loss following bariatric surgery varies greatly.  A weight loss of 50-70% excess weight can be expected 18 months after surgery, but it can vary a lot depending on surgery type, physical activity and dietary habits. The term ‘excess weight’ refers to how much extra weight a person has over a healthy BMI (25 kg/m2).  Achieving a BMI of 25kg/m2 and below is not a realistic goal for the majority of people who undergo bariatric surgery, but they can still achieve clinically significant benefit to their health.

An example of excess weight and weight loss is shown here:

Weight at surgery: 127kg, height: 1.66m, BMI: 46kg/m2
Weight at BMI 25kg/m2: 69kg
Excess weight: 127-69= 58kg
Weight today: 90kg, BMI 32.7kg/m2
Weight lost: 127-90 = 37kg
% excess weight loss: 37÷58 x100 = 63.8%

18-24months after surgery weight loss is expected to slow and stabilise. Sometimes some weight will be re-gained (6-12kg) and then plateau, for others a gradual increase can continue. If weight regain continues, it can be useful to refer the patient for additional support from services such as:

  • Local community dietitians
  • Weight management programmes
  • Specialist tier 3 weight management services
  • Exercise on referral