DIetary Treament Of Obesity Flashcards
Describe the low fat diet used to treat obesity?
Simply reduce amount of fat in the diet.
But weight loss is much more complicated than this. Because firstly, we get the instinctive feeling that if an advice is simple, it may not be a good one. Second, over-consumption of any other foods that are low in fat, is still going to slow down the weight loss or even lead to weight gain. E.g many companies label their product as low fat. However, it has its reason of cutting out fat as it is very energy dense, so elimination means cutting out fairly large amount of energy, potentially leading to energy deficit. But cautions needed.
Low CHO diets?
- Ketogenic: diets such as dr Atkin’s diet (30g of CHO) a day. Promotes production of Ketone bodies. Either through high fat moderate carbohydrate or the other way around. Some very low energy intake.
Other moderate carbohydrate diets include the wellness diet, the zone diet and Mediterranean diet.
Decreased diet variety?
Decreased diet variety promotes weight loss because individuals gets sick of the limited food they can consume. So they stop eating and it contributes to calorie deficit. Increased variety leads to over-consumption so energy excess.
Manipulation of energy density?
Energy density refers to how much energy measured in kj or kcal are contained in certain amount of food items. If we consume lower energy density foods, we will feel satiated without too much calorie consumption, so better limit of our intake. (Studies shown that regardless of percentage of an energy dense macro i.e fat, as long as energy density is the same, then calorie intake remains the same–> we can potentially eat high fat food, as long as energy intake is limited, we will lose weight)
Fundamentally: calorie deficit most important
Low GI？
Low glycemic index food is associated with higher satiety since the food is slowly digested and its glucose is slowly and steadily released into the blood. Which makes blood glucose remain at higher level constantly than high GI. Also, more satiety then leads to reduced food intake, so is good for weight loss.
On the other hand, high GI food means that the food is quickly digested resulting in a peak in blood glucose. So that the body need to bring it back down to normal level by releasing a lot of insulin at once. But this brings the glucose down too much, resulting in a higher glucose level after all because counter-regulatory hormone responses happen i..e too much glucagon released to release the stored glucose.
To be corrected..
Dairy intake?
Shown to help with weight loss. Possible mechanisms include increasing fat excretion in fasces as Ca2+ forms fatty acid soaps i.e. There is 350 kj of energy excreted. Other mechanisms include lipolysis, lipid oxidation and energy expenditure.
Gut biota?
Yes. Studies including swapping gut biota from a fat rat to a skinny rat, the skinny rat later gained weight.
What is the trend of weight loss and metabolic changes shown in the biggest loser?
Immediate result of the competition: significant weight loss, and large proportion of fat loss compared to lean mass loss.
Metabolic adaptation: more reduction in basic metabolic rate than those after surgical intervention. This is a factor influencing long term weight loss. Because with lower BMR, same level of exercise results in less total energy expenditure, so may increase difficulty of maintaining the lost weight.
After 6 years, many regained 87% of their lost weight back.
Intermittent fasting?
How it works: consume normal foods including treats during 5 days a week, 2 days of fasting with significant calorie reduction i.e. Females 500 kcal, and 600 kcal.
Why it could work: calorie reduction in 2 days, appetite regulation ( can survive on lower calories and wholesome foods), less burden so more compliance, eating real foods than discretionary foods, less reduction of BMR compared to chronic restriction.
What does the study say? No significant effect. No difference compared to chronic calorie deficit.
What are the rationale of high protein and low carbohydrate diet ?
2 major reasons this works (supported by studies):
1) High protein diet is more satiating. So easier to eat less and reach/stay in calorie deficit.
2) Reach protein ‘set point’ more quickly. I.e. Feel more satisfied instead of keep on eating food low in protein, exceed calorie limit until the set point is reached. “ protein leverage hypothesis”
Who are the main population to treat in terms of obesity?
Those with BMI over 27, and co-morbidities or metabolic syndromes such as hypertension, insulin resistance and dyslipidaemia.
Other treatments for obesity than diets?
Drugs, surgery, psychological therapies such as cognitive behavioural therapy, mindfulness and motivational interviewing, weight loss centers, gut microbiota?
Goals of obesity treatments?
Reduction in weight, has to be reasonable and in stages
Improvement of psychological and social aspects of individual lives
Reduction of requirement of medication and surgeries
Reduction of co-morbidities
Achievement of individual goals for example fitting into certain clothing sizes
Increased mobility, and increased cv fitness
