Sustainable Weight Loss Flashcards
RYGB
Roux-en-Y bypass - small gastric pouch (15-30mL) on the lesser gastric curvature which is completely divided from the gastric remnant and then anastomoses to the jejunum, get the stomach secretions still
Complication with the RYGB
30 days after the surgery - 4% of patients - bleeding, perforation or leakage - immediate surgical re-intervention
What does RYGB treat? - 3
Not some of the aetiological factors of morbid obesity e.g. obesogenic environment
20-30% long term over 2 years of weight loss and maintenance, >50% of excess body weight
Improvement/remission of many obesity related comorbidities (hypertension, T2D, mellitus, obstructive sleep apnoea and musculoskeletal pain) - 40% of T2D go into remission within days/weeks
What causes the reduced kcal intake after RYGB?
Significantly smaller meal sizes = reduced caloric content
What’s a dominant contributing factor of reduced caloric intake.
Enhanced satiety
Calorie count for post RYGB
Dramatic decrease - 600-700kcal in the first month, then rise to 1000-1800 during the first year.
Changes in behaviour associated with eating after RYGB?
Reported in 1970s using structured interviews that suggested they reached satiety more quickly - common reason of lack of desire for food.
RYGB and endogenous gut hormone responses
Elevated responses for Glucagon like peptide 1, peptide YY respond to mixed meals/oral glucose - may remain high for more than a decade
Why do we think its more than GLP 1 that works after RYGN
Because enhanced GLP 1 signaling is not sufficient to reduce body weight so there should be multiple gut hormone that mediate the increased satiation
Ghrelin and RYGB
Ghrelin deficiency b/c it usually increases after diet induced weight loss
RYGN and neural responses - 2
Reduce hedonic behaviour associated with eating highly palatable and calorie dense foods compared to patients who ha
Selective decrease of reward value of a sweet and fat tastant, but not veggies.
GYFB and total plasma build acids
Pournaras et al - elevated - partly responsible for anorexigenic hormone secretion
What causes the the significant improvement of weight, inflammation and metabolic status after surgery?
Increased bacterial variety
Gut microbiota from GYGB treated mice to non -operated germ free mice
Caused weight loss and reduced fat mass - altered microbial production of short chain fatty acids
hedonic response to high calorie foods compared between RYGB and adjustable gastric banding
lower for RYGBs
Thermogenesis after RYGB - 2
decreased basal metabolic rate but increased meal induced thermosgenesis
RYGB and pancreatic exocrine function
impair it which could contribute to a small amt of fat malabsorption but probably too small to contribute to weight loss
will RYGB result in calorie malabsorption?
not likely
RYGB and unexplained chronic abdominal pain
10%
Iron and RYGB
deficiency due to reduced acid production in the small stomach pouch
B12 and RYGB
deficiency in 70%
folic acid and RYGB
deficiency in 35%
RYGB and hypocalcemia & 25 -hydroxy vit D
hypocalcemia up to 10 % and low serum 25-hydroxy vit D levels in up to half
Major physiological changes that take place after RYGB
exaggerated release of satiety gut hormones with their central and peripheral effects on glycemia and food intake
Understanding the mechanisms of RYGB will
speed up the development of more effective and safer surgical and non-surgical treatments for obesity.
Is the challenge to lose weight?
no its to keep it off
Do diff diets of macros work differently?
no - modest diff in weight loss and metabolic risk factors - little diff in weight and health outcomes in time frames longer than 6 months
National Weight Control Registry looked at adults that have lost more than 13.6 kg of weight and kept it off for a year, tracking 10,000 people their strategies were - 3 +3
formal program 98% diet 94% PA regular meal patterns - prepare and eat at home portion control - limit intake of food and quantity - count calories and food diary weigh in daily
Additional ways of keeping weight off - 12
decrease total energy intake decrease energy density increased dietary fibre decrease fat intake from fast foods fewer sugar sweetened beverages low sugar and low fat foods decreased total alcohol intake increased water intake food diaries increased PA (lifestyle and planned) breakfast everyday behavioural strategies - self monitor, food diary, weigh in, goal setting-fdbk
diet consistency
maintaining same diet regimen across the week and year instead of having cheat days is also important
PA and maintenance of weight loss
essential - less than 10% said they dont engage in PA - lifestyle and planned activities to balance the enery intake and expenditure
how to best use a diet to keep your weight off
Take one that you will find easiest to adhere to long term
How did the Twinkie diet work?
1800kcal cap, 2/3 came from junk food - decreased LDL - increased HDL - decreased body fat multivit everyday
4 treatment options for overweight and obesity
Lifestyle management - diet and PA
Pharmacotheraphy - Liraglutide (GLP-1 agonist) and Orlistat (Xenical)
Metabolic/bariatric surgery - indications: BMI>40, or >35 with diabetes
Not doing anything
What does Orlistat do?
inhibit the breakdown of fat
3 types of bariatric surgery
Roux-en Y gastric bypass
Sleeve gastrectomy
Adjustable gastric band
adjustable gastric band
if you filled the outside thing with saline you can adjust the opening and food wont go down as rapidly
if you reverse the surgery what happens to your weight
Comes back up
adverse effects of bariatric surgery - 6
post operational complications - 4% bleeding, perforations, leakage
mortality 0.1-2%, depending on surgery type
abdominal pain
vit b12, folate, and D deficiency - diff acids
calcium and iron deficiency
bone loss
4 mechanisms of bariatric surgery
increased delivery of food into the midgut
altered appetite and gut satiety hormones
increased thermic effect of food (increased metabolic rate of small bowel)
may be some fat malabsorption
7 altered appetite and gut satiety hormones
increase GLP1 and PYY for years - they dont have to wait for food to get down
ghrelin decreases
altered vagal signaling
altered bile acid signaling - enteroendocrine Lcells and Liver cells (metabolism and more satiety hormones)
modified gut microbiota composition and diversity
conditioned food avoidance due to dumping syndrome (glycemic issues)
reduced hedonic response to palatable food
how many people got bariatric surgery in 2013/14?
6500, increase of 300%
recidivism of weight management
reduced leisure time activity, dietary restraint, self weighing
increased energy intake from dietary fat and increased disinhibition
is our biology broken?
no, we just need to learn to deal with it
