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Flashcards in IASM Case 2: Healthy diet Deck (13)
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Importance of health diet

1. Maintain caloric balance as fuels
2. Maintain dietary requirements as building blocks for biosynthesis
3. Provide specific nutrients for staying healthy
4. Regular supply of essential amino acids, essential fatty acids, minerals, water and nitrogen balance


***Normal glucose metabolism in fed state

1. Insulin from pancreatic beta cells after high carbohydrate meal
—> uptake of glucose into hepatocytes and adipose cells
2. hepatic glycolysis stimulated —> excess glucose —> pyruvate —> Acetyl CoA
3. Excess Acetyl CoA —> fatty acid synthesis
4. Increased fatty synthesis —> increased TAG production
5. TAG synthesised in liver (major site) packaged in VLDL —> uptake by adipose tissue and stored as fat


***Normal fat metabolism after fasting

1. TAG in adipose tissue broken down into glycerol and FA
2. Glycerol transported to liver —> gluconeogenesis
3. FA —> generate energy in muscle, kidney, other tissues
4. FA —> Acetyl CoA by β oxidation —> TCA cycle —> ATP
5. Some FA converted into ketone bodies —> Acetyl CoA in tissues


Balance in diet and physical activity in maintaining healthy body weight

***Daily energy expenditure = Resting metabolic rate + Physical activity + Diet-induced thermogenesis

RMR: energy required to maintain life
- lean body mass / metabolically active tissue mass
- gender (male > female)
- body temperature (increase with body temperature)
- ambient temperature (increase in cold climate)
- hormone (hyperthyroidism)
- body status (pregnancy / lactation)

RMR measurement: Direct calorimetry / Indirect calorimetry (estimate from O2 consumption)

Physical activity: 30% of RMR for sedentary person, 60-70% of RMR for 2 hours moderate exercise / day

DIT: Thermic effect of food, Energy required to process food (digest, absorb, distribute, store), 10% of energy ingested


Importance of regular exercise for weight control

1. Reduce risk of hypertension, coronary heart disease, stroke , diabetes, depression, breast and colon cancer

2. Bone and functional health

3. Key determinant of energy expenditure, fundamental to energy balance and weight control


BMI (body mass index)

- Anthropometric measure to assess weight
- kg/m^2
- ***WHO standards:
- <18.5 underweight
- 18.5-24.9 normal,
- 25-29.9 overweight, 23-27 in HONG KONG
- 30-34.9 obese class I, >27 in HONG KONG
- 35-39.9 obese class II
- >40 obese class III

- easy, cheap, non-invasive
- early understood
- effective used as screening
- widely used, enabling comparisons between populations

- muscular individuals have high BMI
- does not indicate distribution of body fat
- Asians have higher body fat % than Caucasian (cut-offs for Asians are lower)


WHR (Waist-to-hip ratio)

- Anthropometric measure to assess fat distribution
- method to assess adiposity —> indication of abdominal (central/visceral) adiposity with increased risk for CVD, diabetes, hypertension, cancers
- measuring waist circumference / waist-to-hip circumference ratio

- Waist circumference: just above uppermost lateral border of right ilium (end of expiration)
- Hip circumference: level of maximum circumference of hips/buttocks

Threshold for increased CVD risk
Male: WHR >=0.9
Female: WHR >=0.85

- easy, cheap, non-invasive
- easily understood

- emphasis on abdominal adiposity, not informative enough to use in screening
- pregnant women
- recently liposuction of waist / hips
- recently had a meal


Long term complication of obesity

- CVD: Ischaemic heart disease
- Type II Diabetes
- Stroke
- Osteoarthritis
- Obstructive sleep apnea
- Social stigmatisation
- Hypertension
- Hypercholesterolaemia
- Gastroesophageal reflux disease


Adverse health effects of consuming food with high sugar and salt

1. High sugar intake
- obesity (unhealthy weight gain)
- poor nutrition
- less filling than solid forms —> continue to feel hungry despite high calorie value
- alters Ghrelin (hunger hormone) —> consume more food even full
- tooth decay

2. High salt intake
- Water retention —> increased blood volume —> increase cardiac workload, more pressure on vessels
- Stiffen blood vessel —> high blood pressure —> increase CVD risk
—> heart attack
—> hypertension
—> stroke
—> heart failure
—> renal failure
—> oedema
—> osteoporosis (increase Ca loss through urine with more salt intake)


***WHO recommendation of sugar and salt intake

Free Sugar:
- <10% total energy intake (50g / 12 teaspoons) (for daily 2000 kcal intake)
- <5% for additional benefits

- <5g of salt (1 teaspoon) / day
- use iodised salt
- not enough K
- people often unaware of amount of salt consumed (processed foods)


Potential strategies to promote healthy eating and reduce Na and sugar in HK

1. Coherence in national policies and investment plans:
- Increase incentives for retailers to grow, use and sell fresh fruits and vegetables
- Reduce incentives for production of processed food with saturated fats and sugars
- WHO recommendations marketing of food and non-alcoholic beverages to children
- Faster healthy dietary practice (healthy safe and affordable food in institution)
- Food labelling policies
- Taxation, subsidies

2. Encourage consumer demand for healthy food
- promote consumer awareness
- school policies to encourage children to adopt healthy diet
- education about nutrition and healthy diet
- encourage culinary skills
- food labelling that ensures comprehensible information
- nutrition and dietary counselling

3. Appropriate infant and child feeding
- International code of marketing of breast-milk substitutes
- protection of working mothers
- support breastfeeding


Regulation by Tax on added sugar and salt compared to regulation of alcohol

Sugar should be regulated in same way
- Unavoidability, pervasive in society
- Toxicity: high fructose corn syrup —> liver toxicity
- Potential for abuse
- Increase risk of chronic disease —> negative impact on society

On the other side:
- Violate principle of free trade
- Difficulty in law enforcement


Socioeconomic impact of obesity in HK

1. Estimated hospitalisation cost of obesity related risk factor is high
2. Signicant amount of money spent by public on obesity self-management of no proven benefit
3. Cost of loss in productivity
4. Stigmatisation