Since the last Canadian Obesity Guidelines were published in 2006, there is now so much new information to share on this topic in the 2020 Guidelines that fully three chapters are dedicated to this area:


Here are some highlights and interesting points from these three chapters:


Patient selection and preoperative workup:

  • Bariatric surgery is the beginning of a life-long journey. You should educate yourself about the necessary changes required to optimize your long-term outcomes for a healthier life.
  • Remember that a preoperative medical assessment includes screening for sleep apnea – as many as 90% of patients undergoing bariatric surgery have sleep apnea, which has often gone undiagnosed.
  • A nutritional assessment preoperatively is important, and any nutrient deficiencies should be corrected. Mental and functional health status are also important to assess.
  • Because of the risks for postoperative complications associated with smoking tobacco, smoking cessation is mandatory prior to bariatric surgery and must be maintained postoperatively.
  • For people with type 2 diabetes, medications that control blood sugars need to be assessed closely and continuously during the preoperative journey (eg reduction in insulin or other medications with dietary changes or liquid diet; stop SGLT2 inhibitors if on a very low calorie diet due to risk of diabetic ketoacidosis).
  • Blood pressure medications and diuretics (water pills) often need adjustment (reduction) during the preoperative weight loss journey as well.
  • Advanced patient age is not a contraindication (reason not to do) to bariatric surgery. The outcomes and complication rates for patients greater than 60 years of age appear to be comparable to those of a younger population. (note: currently, most bariatric programs have an upper age limit of 60-65)
  • Preoperative weight loss may decrease the difficulty of performing bariatric surgery, minimize blood loss, improved short-term weight loss and short-term complications, as well as decrease operative time. However, longer term studies (4 years) did not show that people who lost weight before surgery did any better with regards to weight loss long term.
  • Because of changes in absorption of some medications after bariatric surgery, you may be asked to change either the type or formulation of your medication that you are currently taking.



Surgery options and outcomes:

  • Bariatric surgery can be considered for people with BMI ≥40 kg/m2 or BMI ≥35 kg/m2 with at least one obesity-related disease to reduce long term overall mortality, to induce control and possibly remission of type 2 diabetes, to improve many obesity related diseases (eg cholesterol issues, hypertension, fatty liver), to induce long term weight loss, and to improve quality of life.
  • Bariatric surgery should be considered in patients with poorly controlled type 2 diabetes despite optimal clinical management and Class I obesity (BMI between 30 and 35 kg/m2)(note: previously, bariatric surgery was only recommended with BMI of 35 or greater)
  • Bariatric surgery may be considered for weight loss and/or to control obesity-associated diseases in patients with Class 1 Obesity (BMI 30-35), for whom optimal medical and behavioural management have been insufficient to produce significant weight loss. (note: previously, bariatric surgery was only recommended with BMI of 35 or greater)
  • The choice of which type of bariatric surgery (sleeve gastrectomy, gastric bypass, or duodenal switch) should be a collective decision including the patient and an experienced multidisciplinary health care team. These surgeries have different levels of effectiveness, as well as differences in potential adverse effects and risks.
  • Adjustable gastric banding should NOT be offered due to unacceptable complications and long-term failure.



Postoperative management:

  • If you have had bariatric surgery, it is important for you to take your nutritional supplements lifelong and to continue to follow the post-bariatric surgical nutrition plan, exercise and any other recommendations given by your original specialist team. By doing this, you will increase your chances of staying healthy and reduce complications that can arise from bariatric surgery.
  • After bariatric surgery, it is possible that there can be a negative impact on mood, relationships, body image, development of addictions, and reduced ability to cope with stress. If you are struggling, discuss this with your original specialist team or, if you have been discharged, with your family doctor.
  • Remember that your lowest weight post surgery will occur between 12 to 18 months. After this, there is a natural increase in weight that occurs. If you are gaining excessive amounts of weight, then discuss this with your bariatric team or primary care provider.
  • If you are 12-18 months post bariatric surgery and are planning a pregnancy, discuss this with your bariatric team, family doctor and obstetrician.
  • We suggest that after a patient has been discharged from the bariatric surgical centre, primary care providers should annually review: nutritional intake, activity, compliance with multivitamin and mineral supplements, weight, assessment of comorbidities, laboratory tests to assess for nutritional deficiencies, and investigate abnormal results and treat as required.
  • We suggest that primary care providers consider referral back to the bariatric surgical centre or to a local specialist for technical/gastrointestinal symptoms, nutritional issues, pregnancy, psychological support, weight regain, or other medical issues.
  • We suggest that bariatric surgical centres provide follow-up and appropriate laboratory tests at regular intervals post-surgery with access to appropriate healthcare professionals (dietitian, nurse, social worker, surgeon, bariatric physician, psychologist/psychiatrist) until discharge is deemed appropriate for the patient. Some patients who have had bariatric surgery may need lifelong follow-up at a bariatric surgical centre.



Be sure to check out the treasure trove of quick reference tables in this chapter including:

  • required vitamin supplements
  • lab monitoring
  • treatment of post op vitamin/mineral deficiencies
  • symptoms that might suggest a nutrient deficiency
  • medications that change in concentration after surgery, and meds not to be crushed


NOTE: This blog is not intended to be a full synopsis of these chapters.  There is a wealth of information in these chapters that are beyond the scope of one blog post. I encourage everyone to read the recommendations and key messages in full, and to dig in to the entire chapters!


Stay tuned for much more on the Obesity Guidelines in coming weeks!


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