9 - Restricted Diets

Question 1

What are restricted diets?

Answer 1

Diets that require a component in the food to be kept within certain limits

Question 2

What is a calorie restriction (CR) diet?

Answer 2

A diet that restricts calorie intake (most are about 30% less) but adequate essential nutrients

Subjects are normal and without any medical conditions

Found to increase lifespan in rodents, fish, dogs and yeast

Question 3

Does calorie restriction (CR) result in longevity in humans?

Answer 3

Some studies suggest that CR in primates did not increase longevity. Genes and healthy diet may matter more
Other studies suggest the ratio of macronutrients plays a more important role
Another study suggests that CR increases lifespan but affects the brain

Question 4

What is the purpose of diet restriction?

Answer 4

Changing eating habits to reduce risk of disease or manage disease

Question 5

What are some medical conditions that need restricted diets?

Answer 5

Obesity - weight management
Cardiovascular diseases - healthy fat diet
Diabetes
High blood pressure
Phenylketonuria (PKU)

Question 6

How can abdominal fatness be defined?

Answer 6

Using waist to hip ratio (WHR). >1.0 for men, >0.85 for women

Question 7

What are some obesity-related trends in the Singapore population (18-69y)?

Answer 7

10. 8% obese (BMI > 30kg/m^2)
11. 1% male, 9.5% female
12. 0% Malay, 16.9% Indian, 7.9% Chinese
13. 0% are high risk (BMI > 27.5 kg/m^2)

Question 8

What are the health risks associated with obesity?

Answer 8

Cardiovascular disease
Diabetes
Atherosclerosis
Inflammation
Some cancers

Question 9

What are the causes of obesity?

Answer 9

Increased calories
Genetic susceptibility
Reduced physical activity

Question 10

What are some weight loss strategies?

Answer 10

Exercise regularly
Small changes to diet (300-500 kcal reduction from usual intake)
Ensure nutrient adequacy by taking foods with high nutrient density but low energy density
Consume lower fat foods (=<30% of total kcal)
Use less cooking oil
Reducing % protein helps reduce fat intake and high energy density foods
Increasing % carbohydrate helps increase fibre and low energy density foods

Question 11

How to maintain weight loss?

Answer 11

Increase high fiber food - promote satiety, lower energy density, high nutrient density
Increase water intake - increase fullness, help in coping with high fiber diet
Avoid empty calories e.g., sweetened drinks and alcohol

Question 12

What are some precautions for weight loss strategies?

Answer 12

Do not compromise on nutrient adequacy
Diet should be well balanced
Nutrient supplements may be required
Lower calories should not lead to feelings of starvation - which may lead to irresistible urge
Beware of fad diets
Beware of weight loss products

Question 13

Why do weight loss products and services thrive?

Answer 13

Success rate is low in retaining weight loss
Social pressure to maintain normal weight
People are willing to try a quick-fix solution
People believe that if a product sells, it must be effective
Some evidence in animal models
Explanation sounds good

Question 14

What are cardiovascular diseases, and some examples?

Answer 14

Diseases of heart and blood vessels

Coronary heart disease (CHD) - blood flow to heart affected, leads to heart attack
Stroke - blood supply to brain is affected

> 30% of total deaths in Singapore is due to cardiovascular diseases

Question 15

What are the functions of LDL and HDL?

Answer 15

LDL transport triglycerides, cholesterol and phospholipid to cells of all tissues
HDL transport cholesterol back to the liver for disposal

Question 16

What is a healthy fat diet?

Answer 16

For weight loss or maintenance

Reduce LDL level and obtain blood lipid balance

Question 17

Healthy fat diet:

What is the recommendation for saturated fat intake?

Answer 17

Total fat 20-35% of energy
Limit saturated fat to 7% total energy - taking lower fat food, cut off fats from meat, reduce cream and butter, replace with carbohydrate

Question 18

Healthy fat diet:

What is the recommendation for cholesterol?

Answer 18

Limit to 200mg
Sources - animal fats

Cholesterol is not essential. Dietary cholesterol has little effect on blood cholesterol

Question 19

Healthy fat diet:

What is the recommendation for trans fatty acid intake?

Answer 19

Avoid trans fatty acid (small quantities are found naturally in meat and milk)

Question 20

Healthy fat diet:

What is the recommendation for unsaturated fatty acids intake?

Answer 20

n-6 polyunsaturated fatty acids (linoleic acid) 5-10% energy
n-3 polyunsaturated fatty acids (α-linolenic acid) 0.6-1.2% energy
Approximately 10% of total can come from longer chain n-6 or n-3 fatty acids

Replace meat with fish - low in saturated fat, suppress inflammation, blood clotting, lowering triglyceride levels

Question 21

What are fat replacers and what are some precautions when using them?

Answer 21

Replace the function of fats in foods (taste, texture and/or cooking properties) with zero or lower calories
Do not contribute to hyperlipidemia (high blood cholesterol)
Can be carbohydrate, protein or fat based

Precaution - fat based fat replacers is able to reduce the absorption of fat soluble vitamin
Avoid deficiency of essential fatty acids

Question 22

What are some examples of fat replacers?

Answer 22

Fat replacers obtained from food components are GRAS (generally recognised as safe)

• Avicel
• Splendid
• Simplese
• Benefat

Fat replacers which are not natural occurring are tested vigorously for safety before it is approved for use
- Olean - can cause diarrhoea and oily stool if consumed in large quantities

Question 23

What is type 1 diabetes?

Answer 23

Insulin dependent diabetes mellitus
Damage of pancreatic cells - unable to produce insulin
5-10% of cases

Question 24

What is type 2 diabetes?

Answer 24

Insulin resistant, not responding to insulin

90-95% of cases

Question 25

What are the problems associated with diabetes?

Answer 25

Cells suffer from lack of sugar (starvation)
Fat used for energy instead, resulting in ketoacidosis in type 1 diabetes
Insulin in type 2 diabetes inhibit fat breakdown, ketoacidosis is less severe, gluconeogenesis results in dehydration
High blood sugar (hyperglycemia) may affect vision, delay wound healing, heart disease, kidney failure, stroke, loss of limbs etc.

Question 26

What are the usual body weights of type 1 and 2 diabetics?

Answer 26

Type 1 - normally not overweight
weight gain may be the side effect of insulin treatment

Type 2 - normally overweight
Overweight can worsen insulin resistance

Question 27

What are some principles of diet management in diabetes?

Answer 27

Balance diet with essential nutrients
Maintain ideal weight
Meet energy needs
Prevent blood sugar variation and keeping it close to normal level
Decrease blood lipid levels, if elevated

Question 28

How can nutrition management in diabetes be achieved?

Answer 28

Consistent carbohydrate content in meals at timed intervals to maintain blood sugar level
Overall calories eaten must be controlled to manage weight over long term
Consumption of carbohydrate must not be lower than 130g per day
Consume low GI foods
Fiber rich foods are encouraged and may improve glycemic control
Healthy fat diet is recommended due to high risk of cardiovascular disease
Protein 15-20% of total
Alcohol - minimise, consume with food to avoid hypoglycemia, may increase triglyceride level

Question 29

GI does not give extent to which blood glucose is raised by a consumption of a particular amount of a food. What does?

Answer 29

Glycemic load (GL) represents blood-glucose-raising potential of specific amount of food consumed

GL = GI x mass of carbohydrate in food / 100

Question 30

What are exchange lists for diabetes?

Answer 30

Exchange lists can be set up for each food group
Foods in the same group should have approximately similar number of calories, composition and effects on blood glucose levels

Question 31

How is blood pressure measured for hypertension?

Answer 31

Systolic (heart beat) pressure/diastolic (heart relax) pressure

Normal - systolic < 120 mmHg, diastolic < 80
Prehypertension - systolic 120-139, diastolic 80-89
Hypertenstion - systolic >= 140, diastolic >= 90

Question 32

How much sodium is there in 1000mg of salt?

What does excess sodium in hypertension cause?

Answer 32

400mg

Na+ causes dehydration of cell and increase in blood pressure

Question 33

What is a DASH diet?

Answer 33

Dietary Approaches to Stop Hypertension - people with cardiovascular disease and high blood pressure, reduce asthma symptoms, help with migraine, gastritis and ulcers

Reduce intake of sodium which is related to chronic diseases

Question 34

How to reduce salt and sodium?

Answer 34

Choose fresh or frozen food, no salt added/rinse salt from food
Choose processed food carefully
Choose low salt versions of soy sauce, teriyaki sauce
Smoked, corned, pickled food may have added salt
Many snack foods also contain added salt

Question 35

Gluten restricted diet - who is affected, what foods to avoid?

Answer 35

People with celiac sprue

Foods to avoid - all wheat, rye, oats, barley and buckwheat products
Hidden gluten e.g., sausage soy sauce, sauce and gravy mixes

Create an exchange list for each food category

Question 36

Lactose restricted diet - who is affected, what foods to avoid?

Answer 36

Lactose intolerant

Foods to avoid - foods with lactose, casein, whey, non-fat dry milk solids
Foods containing low level of lactose is possible for the less sensitive e.g., yoghurt, aged-cheese, buttermilk

Caution - lack of Ca2+, can consider adding lactase in milk