IASM Case 2: Healthy diet Flashcards
Importance of health diet
- Maintain caloric balance as fuels
- Maintain dietary requirements as building blocks for biosynthesis
- Provide specific nutrients for staying healthy
- Regular supply of essential amino acids, essential fatty acids, minerals, water and nitrogen balance
***Normal glucose metabolism in fed state
- Insulin from pancreatic beta cells after high carbohydrate meal
—> uptake of glucose into hepatocytes and adipose cells - hepatic glycolysis stimulated —> excess glucose —> pyruvate —> Acetyl CoA
- Excess Acetyl CoA —> fatty acid synthesis
- Increased fatty synthesis —> increased TAG production
- TAG synthesised in liver (major site) packaged in VLDL —> uptake by adipose tissue and stored as fat
***Normal fat metabolism after fasting
- TAG in adipose tissue broken down into glycerol and FA
- Glycerol transported to liver —> gluconeogenesis
- FA —> generate energy in muscle, kidney, other tissues
- FA —> Acetyl CoA by β oxidation —> TCA cycle —> ATP
- 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
- Reduce risk of hypertension, coronary heart disease, stroke , diabetes, depression, breast and colon cancer
- Bone and functional health
- 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
Advantage:
- easy, cheap, non-invasive
- early understood
- effective used as screening
- widely used, enabling comparisons between populations
Disadvantage:
- 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
Advantage:
- easy, cheap, non-invasive
- easily understood
Disadvantage:
- 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
- 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 - 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
Salt:
- <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
- 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 - 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 - 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
- Estimated hospitalisation cost of obesity related risk factor is high
- Signicant amount of money spent by public on obesity self-management of no proven benefit
- Cost of loss in productivity
- Stigmatisation
