Biochemistry: Chapter 9: Weight Management

Front 1

How does being overwt develop (4)?

Back 1

1. During growth, number of fat cells increase

2. When energy intake > expenditure, fat cells increase in size

3. When fat cells reach max size, if [intake > expenditure] continues, the number of cells can increase.

4. With loss of fat, the size of the cell decreases, but not the number.

Front 2

What is LPL?

Back 2

lipoprotein lipase

Front 3

Where is LPL present?

Back 3

In the membranes of fat cells. So more cells = more LPLs. More LPL activity leads to more efficient fat storage.

Front 4

LPL is localized in fat cells. What does this mean for women?

Back 4

Breasts, Hips, and Thighs.

Front 5

LPL is localized in fat cells. What does this mean for men?

Back 5

Abdoment (central obesity)

Front 6

Fat breakdown enzymes is less active where?

Back 6

It is less active in the lower body than in the upper body. This means it is difficult to lose weight in the hips and thighs.

Front 7

What is Set-Point theory?

Back 7

Biochemical/Physiological processes tend to counterbalance changes.
For example:

1. Wt loss leads to an increased synthesis of LPL which leads to more fat storage.

2. Wt loss leads to decreased energy expenditure and this leads to wt gain

3. Wt gain leads to increased energy expenditure and this leads to wt loss.

Front 8

What are the "causes" of obesity?

Back 8

Genetic factors and personal choices.

Front 9

How are genetic factors related to obesity?

Back 9

They may determine or influence susceptibility but do not cause obesity.

Front 10

What does the ob gene code for?

Back 10

Leptin. This suppresses appetite and increases energy expenditure.

Front 11

If there is an increase in body fat what happens to leptin?

Back 11

Leptin is synthesized and its conc. in the blood increases. This results in a suppression of appetite and increases energy expenditure.

Front 12

If there is a loss of body fat what happens to leptin?

Back 12

The concentration of leptin in the blood decreases. This results in increased appetite and decreases energy expenditure.

Front 13

A defective ob gene leads to what?

Back 13

Uncontrolled wt gain.

Front 14

Some, but not most, obese people have a ? ? ?.

Back 14

Some, but not most, obese people have a defective ob gene.

Front 15

One problem with obese people may be that their fat cells are ? to the action of leptin.

Back 15

One problem with obese people may be that their fat cells are resistant to the action of leptin (analogous to Type 2 diabetes)

Front 16

Remember: What is problem in Type II diabetes?

Back 16

Type II has enough insulin but just can't use it.

Front 17

What are leptin effects mediated by?

Back 17

Neuropeptide Y (NPY)

Front 18

What is NPY?

Back 18

A peptide hormone that stimulates the appetite and reduces energy expenditure.

Front 19

What does increased leptin cause?

Back 19

1. Increased leptin decreases appetite and increases energy expended

2. It causes a decrease in NPY

Front 20

What does NPY do to energy expenditure and appetite?

Back 20

increased NPY = increased appetite = decreased en. exp

Front 21

What does leptin do to energy expenditure and appetite?

Back 21

Increased leptin = decreased app = increased en exp

(because it decreases NPY)

Front 22

What does Ghrelin do?

Back 22

It stimulates appetite and promotes efficient energy storage.

Front 23

What causes changes in ghrelin level?

Back 23

PYY, a peptide secreted by GI cells in response to food intake, lowers ghrelin levels.

Front 24

What effects do PPY have?

Back 24

Opposite effects of Ghrelin by acting on Ghrelin. (so it decreases appetite and decreases energy storage)

Front 25

There is a clear correlation between being overwt and what diseases?

Back 25

1. Cardiovascular disease

2. HTN

3. Diabetes

Front 26

What does everyone experience in losing wt?

Back 26

Everyone experiences short-term wt fluctuations. (eg. water weight)

Front 27

What percent of all people who lose wt maintain that loss for at least a year?

Back 27

Only 5%

Front 28

What does "weight-cycling" ("yo-yo") decrease, what does it increase?

Back 28

It decreases the probability of long-term wt loss, and appears to increase the risk of chronic disease (eg, type 2 diabetes)

Front 29

What is better then "weight-cycling"?

Back 29

Stability, even if overweight, is better than cycling.

Front 30

What are the options for losing weight?

Back 30

If a person has clear health problems (like HTN) and a high BMI, depending on the seriousness, the options are:

1. Surgery

2. Medications

3. Diet modification

Front 31

What does one need to be cautious about in the drug treatment of obesity?

Back 31

1. Short-term use : in conjunction with diet-control and exercise, can lose ~10% of wt but regain is common

2. Long-term: risks and benefits not fully understood

Front 32

List 2 Rx medications approved by the FDA for long-term use?

Back 32

1. Sibutramine (Meridia)

2. Orlistat (Xenical)

Front 33

How does Sibutramine (Meridia) work?

Back 33

Suppresses appetite by inhibiting serotonin reuptake (a SSRI)

Front 34

How does inhibiting serotonin reuptake suppress appetite?

Back 34

It is a neurotransmitter, which suppresses appetite and induces fatigue. Low levels are associated with depression. Any agent that prevents its reuptake increases its concentration.

Front 35

Sibutramine (Meridia) should not be used by whom?

Back 35

Anyone with high BP

Front 36

How does Orlistat (Xenical) work?

Back 36

It inhibits pancreatic lipase, blocking fat digestion and absorption.

(this is now available OTC)

Front 37

What is an FDA medication for losing weight approved for OTC use? How does it work?

Back 37

Benzocaine (Diet Ayds, Slim Mint): It anesthetizes the tongue, reducing taste sensation.

Front 38

What is a drug that the FDA has not approved?

Back 38

Phenylpropanolamine (mkted under various names like Dexatrim).

Multiple possible side effects: dry mouth, rapid pulse, nervousness, sleeplessness, htn, irreg heartbeat, kidney failure, seizures, strokes.

Front 39

What is brown fat?

Back 39

When uncoupling allows the body to use energy without producing ATP. A little uncoupling may be OK but a lot is not.

For example DNP is an uncoupler that at too high a concentration is dangerous. It burns energy without ATP so there is no storage and so there is decreased wt but disastrous side effects.

Front 40

What is St. John's wort?

Back 40

An herbal OTC that appears to suppress appetite.

Front 41

What is ephedra/ephedrine?

Back 41

Herbal product that can be alone or with caffeine. Extracted from ma huang ("natural"). Showed promise for obesity tx. It is now implicated in serious problems. The sale is banned by the FDA.

Front 42

In dieting the primary focus must be on what?

Back 42

Health improvement, not just wt loss.

Front 43

How much wt loss can be beneficial?

Back 43

Even a modest wt loss (like 5 lbs) can be beneficial if sustained.

Front 44

What is a reasonable goal recommended for a reasonable and sustainable wt loss?

Back 44

5-10% of total body wt.

Front 45

How long should you give yourself to lose 10% of your body wt?

Back 45

6 months

Front 46

To lose 10% of 200lbs what should you aim to lose weekly?

Back 46

1 lb/week

Front 47

What does 1 lb of fat equal in kcal?

Back 47

3500 kcal

Front 48

What is a reasonable amount of weight to lose a week?

Back 48

1/2 - 2 lb/week

(1750-7000kcal week)
(250-1000 kcal/day)

Front 49

List 7 components of an eating plan to reduce wt.

Back 49

1. Reduce energy intake (eg, by 500kcal/day)

2. Maintain nutritional adequacy

3. Small portions

4. Include complex carbs

5. Minimize fats

6. Minimize "empty calories"

7. Drink plenty of water

Front 50

How might you maintain nutritional adequacy?

Back 50

Make sure you have high nutrient density and never eat less than 1200kcal/day. So you need to keep in 'good' foods (vit., min., and proteins) and cut empty calories.

Front 51

It is important to include complex carbs in any eating plan, esp what kind?

Back 51

Fiber

Front 52

What kind of fats should esp. be minimized in a diet plan?

Back 52

Saturated fats.

Front 53

What are some 'empty calories' that can be minimized in a diet plan?

Back 53

Fats, sugars, and alcohol

Front 54

What kind of fat is primarily decreased by exercise? What cannot be done?

Back 54

Abdominal fat. You cannot target wt loss to other areas by targeting exercise.

Front 55

What is the most effective way for physical activity to help control appetite?

Back 55

Sustained activity of moderate intensity.

Front 56

List 4 psychological factors that may aid wt control.

Back 56

1. Set reasonable (attainable) goals

2. Find reasonably enjoyable ways of reaching these goals

3. Support groups (wt watchers) may help

4. If habits are unchanged, there is a much greater probability of maintaining the wt loss, which should be the goal.

Front 57

What is not as prevalent as overweight in developed countries?

Back 57

Underweight

Front 58

What is the solution to being underwt?

Back 58

Must combine diet and exercise.

Front 59

List 6 components of a diet for underwt individuals?

Back 59

1. Emphasize high energy foods (even fats, esp. mono and polyunsat fat)

2. Regular meals

3. Large portions

4. Extra snacks

5. Juice and milk

6. If exercising more, need to increase caloric intake.