Bariatric/metabolic surgery has proven benefits for weight loss, improvement in metabolic/inflammatory state and resolution of medical co-morbidities related to obesity.
With anatomical and neuro-endocrine changes, after surgery there is a combinations of reduction in hunger, increased satiation and alteration in gut microbiota as well as changes in eating behaviour and food preferences.
The Bariatric Analysis and Reporting Outcome System (BAROS) assess health related quality of life, co-morbidities and complications after surgery.
The Bariatric Surgery Registry (BSR) (by volunteering surgeons/hospitals) is a registry/audit of all the bariatric/metabolic surgical procedures performed in Australia and New Zealand to assess weight loss, resolution of T2DM and complications after surgery.
But often these reporting systems does not properly evaluate food tolerances, post op eating habits, diet and lifestyle choices of the patients. A separate food tolerance test questionnaire is needed to assess the tolerance to different food groups and satisfaction with the diet.
There may be a change in taste and smell perception that affect food preferences after bariatric surgery. On the positive side some studies have shown a decreased intake of high fat, high carbohydrate and high sugar foods.
But food intolerances if severe or persist may lead to loss of muscle mass and nutritional deficiencies.
Working with the patients who has undergone restrictive/hypoabsorptive/malabsorptive bariatric procedures (sleeve, one anastomosis, Roux Y gastric bypass, SADI-S or others) it is the role of the dietitian to focus the patient’s attention on:
- Healthy eating (good portion size, good food choices, good eating habits)
- Food tolerances, energy and protein intake
- Adequate vitamin/mineral intake and avoiding micronutrient deficiencies
- Changes in body composition
Successful outcome after bariatric/metabolic surgery should be reported as adequate total body weight loss (%TBWL), resolution of medical co-morbidities, improvement in health related quality of life, reduction in premature cardio-vascular or cancer related mortality, etc plus positive impact on a patient’s dietary changes, eating behaviour and body composition.
Bioelectrical impedance tests can also be done to assess fat free mass, fat mass, muscle mass and FM/FFM ratio.
Exercise is an essential part of the effective weight loss and long-term weight maintenance. Even though morbidly obese post op patients can often safely participate in an exercise program or physical training, most don’t do half as much of the recommended exercise or accumulate over 150 minutes of exercise a week.
Individuals who successfully maintained weight loss over the long term (5 years or more) often report a significant reduction in sedentary activities and active participation in physical activity.
Exercise is necessary to:
- Maintain lean body or skeletal muscle mass
- Positively influence the metabolic rate
- Help to maintain active bone metabolism and bone mineral content
- Improve cardio-vascular function and improved health outcomes
- Exercise also been associated with better eating habits and improved adherence to dietary guidelines
- Positively affects eating behavior, cognitive function and motivation levels
Monitoring for micronutrient deficiencies
After hypoabsorptive/malabsorption surgery, it is recommended that lifelong multivitamin replacements be prescribed and blood test monitoring is necessary at regular intervals.
This is an example, more blood test may be needed for some other patients.
- Iron studies may be tested every 3-6 months in the first year, then once or twice annually.
- Folic acid levels may be tested every 3-6 months in the first year, then once or twice annually.
- Vitamin B12 may be tested every 3-6 months in the first year, then once or twice annually.
- Vitamin D may be tested every 3-6 months in the first year, then once or twice annually.
- Thiamine may be tested every 3-6 months in the first year. It should be tested if the patient has been vomiting.
Annual blood tests should be done for vitamin A, B6, copper, magnesium, selenium and zinc
If there are micronutrient deficiencies detected, replacement doses above daily recommended may be needed and more frequent blood test is mandatory.
Special mention for pregnant ladies after bariatric surgery
Higher doses of folic acid may be needed such as 4-5g a day
Iron and vitamin B12 replacement is almost routinely given
Calcium and vitamin D supplements >50nmol/L is recommended
Caution with vitamin A supplement because it is potentially teratogenic
Fetal growth monitoring with ultrasound at 28, 32 and 36 weeks is a minimum
Blood tests such as HbA1C is performed instead of OGTT
Table 1. Vitamins replacements and deficiencies
|Vitamins and RDI||Food sources||Deficiencies|
|A (retinol) 1500-3000mcg||Green leafy vegetable, carrots, pumpkins Orange, squash, liver||Night blindness, hyperkeratosis|
|B1 (thiamine) 12mg||Eggs, pork, liver Brown rice, vegetables, oat meals, potatoes||Cardiovascular problems (wet Beri-Beri) Nervous system (dry Beri-Beri) Wernicke’s encephalopathy Korsakoff psychosis|
|B2 (riboflavin) 1.3mg||Dairy, bananas, green beans, asparagus||Sore mouth and tongue, ariboflavinosis|
|B3 (niacin) 16mg||Meat, fish, eggs Vegetables, mushroom, nuts||Pellagra|
|B5 (panthothenic acid) 5mg||Meat, broccoli, avocado||Parasthesia|
|B6 (pyridoxine) 1.5 -5 mg||Meat, vegetable, nuts, banana||Dermatitis, glossitis Anaemia, peripheral neuropathy|
|B7 (biotin) 30mcg||Egg yolk, liver Vegetables, peanuts||Dermatitis, enteritis|
|B9 (folic acid) 400-800mcg||Green leafy vegetables, spinach, peanuts Pasta, cereal, bread, beans, liver||Megaloblastic anaemia Neural tube defects|
|B12 (cobalamin) 350- 500mcg||Meat||Megaloblastic anaemia|
|C (ascorbic acid) 90mg||Fresh fruits, vegetables, liver||Gingivitis, scurvy|
|D3 (cholecalciferol) 75mcg or 3000 IU||Fish, eggs, liver, mushroom Sunlight exposure||Rickets, osteomalacia|
|E (tocopherol) 15-20mg||Fruits, vegetables, grains, nuts, seeds||Reduced balance and reflexes|
|K (phylloquinone) 1mg||Green vegetables, gut bacteria||Bleeding disorder|
- Please note: high levels of vitamin B6 may be associated with peripheral neuropathy (numbness, parasthesia, burning sensation in peripheries)
Table 2. Mineral supplements and function
|Sodium||Salt, milk, spinach||For fluid and electrolyte balance, blood pressure control|
|Chloride||Salt||For electrolyte balance, gastric acid secretion|
|Potassium||Legumes, bananas, tomatoes, grains, beans, spinach||For electrolyte balance|
|Calcium||Dairy products, eggs, nuts, seeds, green leafy vegetables||For bone structure integrity|
|Phosphorus||Red meat, dairy products, fish, rice, bread||For bone structure integrity|
|Magnesium||Nuts, soy, vegetables, tomatoes||For cell energy and bones|
|Iron 18mg (45-60mg for young females)||Meat, eggs, grains, beans, vegetable, lentil||For red blood cell synthesis and function|
|Iodine||Iodinized salt, cheese, eggs, strawberry, yoghurt||For thyroid function and immune system|
|Copper 2mg||Green vegetables, mushroom, seeds, nuts||For cell enzyme function|
|Manganese||Grains, beans, rice, berry||For cell enzyme function|
|Selenium||Fish, nuts, mushroom||Anti-oxidant|
|Molybdenum||Tomato, carrot, onion||For cell function|
|Zinc 8-22mg||Oyster, seafood, meat||For skin, hair and nail function, wound healing|
Table 3. Calcium deficiency and osteoporosis
Osteomalacia is defective bone mineralization due to vitamin D deficiency
Osteoporosis is defective bone formation
Bone mineral density (BMD) is measured with a nuclear medicine DEXA scan
|Normal||BMD within 1 SD adult mean (T score > -1)|
|Osteopenia||BMD -1 to -2.5SD below adult mean (T score -1 to -2.5)|
|Osteoporosis||BMD >2.5SD below adult mean (T score below -2.5)|
|Severe osteoporosis||BMD >2.5SD below adult mean with pathological fractures|