Nutritional Factors

1
Nutritional Factors

• Influencing Body Composition

2
Overconsumption

• The government recommends 1600 calories a day for
  the average sedentary woman and 2200 for men.
• In 2000, our reported per capita daily caloric
  consumption was 1877 for women and 2618 for men.

3
Nutrition and Exercise

• Where do we get the energy for movement?
• What should we eat to insure optimal health and
  fitness?

4
Nutrition and Exercise

• Energy for movement comes from the food we eat.
• The three sources of energy are
• Carbohydrates
• Fats
• Proteins

5
Nutrition and Exercise

• General Recommendations
• CHO 55-65
• CNS
• Primary fuel source
• Only anaerobic fuel source
• Required for fat metabolism
• Required for protein metabolism

6
Nutrition and Exercise

• Fat 20-30
• Major fuel source for endurance activity
• Essential component of cell membranes and nerve
  fibers
• Insulation
• Shock absorption
• Hormone production
• Fat soluble vitamins

7
Nutrition and Exercise

• Fat
• High in kcal per weight
• Low fat lt20
• Read labels - for something to be low fat, there
  should be no more than 1 gram of fat for every 50
  kcals.
• 100 kcals 2 g fat 18 fat (9 kcals per gram
  of fat)

8
Nutrition and Exercise

• Protein 10-15
• Growth and maintenance of lean tissue
• Repair of damaged tissue
• Fuel source during starvation

9
Old Food Guide Pyramid
10
Food Guide Pyramid

• Key Points (2004)
• At least 3 one-ounce servings of whole grains
  each day (instead of refined sugars and white
  bread)
• Whole grains contain more fiber which has been
  shown to reduce the risk of heart disease and
  diabetes
• Increase daily intake of fruits and vegetables,
  whole grains, and nonfat or low fat milk and milk
  products

11
Food Guide Pyramid
www.mypyramid.gov
12
Nutrients

• CHO
• Fat
• Protein
• Water
• Vitamins
• Minerals

13
Vitamins

• Fat Soluble
• A D E K
• Water Soluble
• B Complex
• C

14
Free Radicals and Antioxidants

• Free-radical generation increases after acute
  exercise and potentially causes oxidative tissue
  damage.
• May lead to cancer.
• Consuming antioxidants (e.g., vitamin E and
  ß-carotene) can trap free radicals and prevent
  this action.

15
Minerals

• Calcium
• Phosphorus
• Magnesium
• Iron
• Potassium
• Sodium

16
Calcium

• RDA for most adults 1000 mg
• For teenagers 1300 mg
• For those over 50 1200 mg
• Highest food sources are dairy and
  calcium-fortified orange juice.

17
Iron

• RDA 8 mg for men and postmenopausal women
• 18 mg for pre-menopausal women
• 27 mg for pregnant women
• Upper limit 45 mg or stomach upset can occur.

18
Zinc

• RDA 11 mg for men, 8 for women
• Upper limit 40 mg
• More can block absorption of another vital
  nutrient, copper.

19
Water

• Important before, during, and after physical
  activity.
• 2.5 liters per day.
• Major factor limiting exercise performance.
• Thirst.

20
Dieting

• Starvation diets will cause weight loss.
• However, they also cause physiologic dysfunction
  and potentially death.
• In addition to fat loss, you lose muscle mass,
  bone mass, and water volume.

21
Yo-Yo Dieting

• The more you diet, the fatter you become.
• When you lose, you lose muscle, fat, water, and
  bone.
• When you return to your normal lifestyle, you add
  on fat and water, but unless you increase
  activity levels drastically, you dont add bone
  or muscle mass.

22
Fad Diets

• Why are they so popular?
• They give the false impression that you can eat
  what you like, in the quantities that you want,
  without having to exercise, and still lose
  weight.
• Very seductive message.

23
Low Carb

• Hype
• Carbs are not healthy
• Carbs negatively impact blood sugar levels
  through high glycemic index raising insulin
  levels
• Low blood sugar leads to hunger
• Invented concept of Net Carbs

24
Low Carb

• Facts
• Low blood sugar hasn't been directly linked to
  hunger.
• Unless you have diabetes, blood sugar remains
  generally stable anyway.
• When you stop eating carbohydrates, your brain
  stops regulating serotonin, a chemical that
  elevates mood and suppresses appetite.

25
Low Carb

• Facts
• Only carbohydrate consumption naturally
  stimulates production of serotonin.
• When serotonin is made and becomes active in your
  brain, its effect on your appetite is to make you
  feel full before your stomach is stuffed and
  stretched.
• The brain makes serotonin only after a person
  consumes sweet or starchy carbohydrates.

26
Low Carb

• Facts
• The kicker is that these carbohydrates must be
  eaten in combination with very little or no
  protein.
• This can explain why people may still feel hungry
  even after they have eaten a 20-ounce steak.
• Their stomachs are full but their brains may not
  be making enough serotonin to shut off their
  appetites.

27
Low Carb

• August 1st, 2005 Atkins Nutritionals declares
  bankruptcy

28
Body Composition Questions

• Why do low-carbohydrate diets produce such a
  rapid weight loss?
• Diets that limit or totally exclude CHO produce a
  rapid weight loss.
• When CHO intake is low, muscle glycogen stores
  are depleted rapidly.

29
Body Composition Questions

• For every gram of CHO, 3 grams of H20 are stored
  in the body.
• When glycogen stores are depleted, the loss of
  water leads to a dramatic weight loss because
  each liter of water weighs approximately 2 lbs.

30
Body Composition Questions

• The weight is regained rapidly, however, when CHO
  intake returns to normal.

31
Protein Power

• 850-1,100 kcal/d
• High protein

32
The Zone

• 1,300 kcal/d for women and 1,700 kcal/d for men
• Follow the 40-30-30 rule
• No foods are off limits, but they claim some
  foods are better than others
• Example broccoli, celery, and grapes good
• Cereal, bagels, and bananas bad
• No real justification for these classifications

33
Sugar Busters!

• 1,200 kcal/d with 28 of total energy intake from
  fat
• 33 of total energy intake from protein

34
South Beach Diet

• Steer clear of bread and beer (maltose)
• No fruit, bread, sugary snacks, potatoes, pasta,
  or rice
• No scientific support for these recommendations,
  but at least allows whole grains, some fruit
  (later), and cuts back on saturated fat

35
Nutrition Questions

• Why are low carbohydrate diets unsafe?
• Low CHO intake may lead to fatigue, hypoglycemia,
  and ketosis.

36
Nutrition Questions

• Low carb diets are detrimental to anaerobic work
  capacity because of reduced muscle glycogen
  stores and decreased rate of glycolysis.

37
Nutrition Questions

• Many of the fad diets (Atkins Diet Revolution,
  Sugar busters, the Zone) result in weight
  reduction primarily because they are low calorie
  diets.

38
Nutrition Questions

• Low carb diets are high in fat, saturated fat,
  and cholesterol.

39
Nutrition Questions

• The nature of low carb diets is a diet low in
  fruits, vegetables, grains, and beans.
• These foods are all high in health promoting and
  disease preventing properties.

40
Nutrition and Exercise

• Do we need to consume large amounts of protein if
  we exercise and wish to increase muscle mass?

41
Nutrition and Exercise

• Recommended Levels of Protein Consumption
• RDA Sedentary Endurance Strength
• g/kg/day 0.8 1.2 - 1.4 1.4 - 2.0

42
Nutrition and Exercise

• No valid evidence exists supporting the notion
  that protein intake exceeding 1.8 - 2.0 will
  provide additional advantage
• International Journal of Sports Nutrition

43
Nutrition and Exercise

• The recommended levels may be reached within the
  total protein percentage recommendations of
  10-15 of all calories consumed daily
• International Journal of Sports Nutrition

44
Nutrition and Exercise

• Example
• 220 lbs male 100 kg
• excessive intake 2.0 (g/kg/day)
• daily need 200 grams
• typical consumption 6000 kcals
• 10-15 of 6000 kcal 600 -900 kcal of protein
• divided by 4 kcals per gram
• 150-250 grams of protein.

45
Amino Acids and Protein

• In all but a few exceptional cases, the maximal
  contribution of protein as an energy source
  during exercise ranges between 2 and 10 of the
  total energy expended.
• (Gibala Hargreaves, and Tipton, 2000)

46
Amino Acids and Protein

• In theory, amino acids could contribute to
  carbohydrate metabolism during exercise, but
  there is no hard evidence that this occurs or has
  any bearing on sport performance.
• (Gibala Hargreaves, and Tipton, 2000)

47
Amino Acids and Protein

• Supplementation of the athletes diet with
  branched-chain amino acids apparently does not
  benefit exercise performance.
• (Gibala Hargreaves, and Tipton, 2000)

48
Amino Acids and Protein

• The most important factors for optimizing growth
  when one performs resistance exercise are
• Adequate resistance
• Adequate caloric consumption, including just
  after lifting
• Plenty of rest between sessions
• (Gibala Hargreaves, and Tipton, 2000)

49
Amino Acids and Protein

• With rare exceptions athletes require 1.2 1.6
  grams of protein per kg day.
• This amount of protein can almost always be
  obtained in the normal diet.
• (Gibala Hargreaves, and Tipton, 2000)

50
Amino Acids and Protein

• There is no solid evidence that special mixtures
  of amino acids provide any advantage over normal
  dietary proteins in stimulating muscle growth.
• (Gibala Hargreaves, and Tipton, 2000)

51
Nutrition Questions

• Are high-protein diets safe?
• High-protein diets that limit CHO intake promote
  muscle tissue loss.
• When CHO intake is restricted, the glucose needs
  of the body are met by breaking down proteins.

52
Nutrition Questions

• Excessive protein intake does not promote protein
  synthesis.
• Instead the excess protein is metabolized.

53
Nutrition Questions

• The amino acids are deaminated, the excess
  nitrogen is excreted in the urine as urea, and
  the remaining carbon skeleton is converted to
  glucose or used as an energy fuel.

54
Nutrition Questions

• Some high-protein diets require drinking large
  quantities of water to prevent the dehydration
  caused by excess urea production and to wash away
  ketone bodies.

55
Nutrition Questions

• Dehydration and the additional stress placed on
  the kidneys may be potentially dangerous,
  especially for individuals with kidney problems
  or gout.

56
Nutrition Questions

• Protein intake above 2.8 g/kg/d has been shown to
  impair renal function.
• High-protein diets may promote urinary calcium
  loss which is particularly a concern for women
  bodybuilders.

57
Nutrition Questions

• Are high-fat diets unsafe?
• Yes
• They produce high levels of serum cholesterol and
  triglycerides which may lead to atherosclerosis.

58
Nutrition Questions

• Typically high-fat diets are high in calories,
  therefore a smaller volume of food must be
  consumed.
• There are no metabolic pathways in the body for
  converting fatty acids to glucose, so excess fat
  is stored in adipose tissue.

59
Nutrition Questions

• What is the danger of fasting or skipping meals
  to promote weight loss?
• Potential side effects include kidney
  malfunction, hyperuricemia, loss of hair,
  dizziness, fainting, and muscle cramping.

60
Nutrition Questions

• When the body is deprived of food, it responds by
  increasing the fat-depositing enzymes and storing
  more fat.
• The body will also metabolize protein to meet its
  energy needs.
• Body will absorb more of the food that appears in
  digestive system.

61
Nutrition Questions

• Why should a fat loss diet include at least
  55-65 carbohydrates?
• CHO helps maintain normal function of the nervous
  system because nerve tissue relies solely on
  glucose as a fuel for energy.

62
Nutrition Questions

• Consuming adequate amounts of CHO on a daily
  basis prevents the depletion of glycogen stores
  and the need to synthesize glucose from the
  bodys protein (protein-sparing effect).

63
Nutrition Questions

• When glycogen stores are depleted, the glucose
  needs of the body are met through the breakdown
  of muscle protein.
• This leads to a loss of lean tissue rather than
  fat.

64
Nutrition Questions

• CHO is also essential for fat metabolism.
• When CHOs are restricted or CHO stores are
  depleted, more fatty acids are mobilized from
  adipose tissue that can be metabolized by the
  body.

65
Nutrition Questions

• This results in the incomplete breakdown of
  lipids and the formation of ketone bodies that
  may cause ketosis.

66
Nutrition Questions

• In addition, muscle glycogen and glucose are the
  primary fuels used during intense, short-term
  exercise and prolonged, submaximal exercise.

67
Nutrition Questions

• Inclusion of adequate amounts of CHO in the diet
  prevents depletion of muscle glycogen and the
  consequent reduction in endurance performance.

68
Sugared Drinks

• High levels of intake of sugar-sweetened drinks
  and of fruit juice raise weight over time in
  educated women in their 30s (Schulze, 2004)
• Higher intake of diet soft drinks reduces weight
  gain

69
Sugared Drinks

• Higher take of sugar-sweetened drinks raise the
  risk for type 2 diabetes in women without a
  family history of diabetes.
• Does not appear true for fruit juice

70
Sugared Drinks

• Low levels of sugar-sweetened drink intake does
  not increases weight gain or diabetes over time.

71
Athletes and Nutrition

• Swimmer Michael Phelpss next career may be in
  competitive eating.
• Besides grabbing five gold medals at the Beijing
  Olympics so far, making him the winningest
  Olympic athlete ever, hes got to be setting new
  marks on the chow line.
• A New York Post account of Phelpss wait for it
  12,000-calorie-a-day diet, gave us a stomachache.
  

72
Athletes and Nutrition

• Could one human being really consume that much
  and still be in Phelpss shape?
• And could this possibly be healthy for Phelps,
  even considering his five-hours-a-day,
  six-days-a-week exercise regimen?

73
Athletes and Nutrition

• Heres Phelpss typical menu.
• No, he doesnt choose among these options.
• He eats them all, according to the Post.
• Breakfast Three fried-egg sandwiches loaded with
  cheese, lettuce, tomatoes, fried onions and
  mayonnaise. Two cups of coffee. One five-egg
  omelet. One bowl of grits. Three slices of French
  toast topped with powdered sugar. Three
  chocolate-chip pancakes.

74
Athletes and Nutrition

• Lunch One pound of enriched pasta. Two large ham
  and cheese sandwiches with mayo on white bread.
  Energy drinks packing 1,000 calories.
• Dinner One pound of pasta. An entire pizza. More
  energy drinks.

75
Athletes and Nutrition

• Does a diet like this make sense even for a
  calorie-incinerating human swimming machine?
• If you eat fewer calories than you burn
  exercising, you lose weight.

76
Athletes and Nutrition

• But an athlete like Phelps, who exercises up a
  storm, has to worry about eating enough to
  replenish the scads of calories hes burned.
• If he doesnt, his body wont recover, the
  muscles will not recover, there will not be
  adequate energy stored for him to compete in his
  next event.

77
Athletes and Nutrition

• But what about the choice of foods?
• All those eggs and ham and cheese cant possibly
  be good for him, can they?

78
Athletes and Nutrition

• Says Klion, I think for him, because of his
  caloric demands, he can probably eat whatever he
  wants to.
• And besides, Klion says, if youve got to eat
  that much, it better be enjoyable, or you wont
  be able to keep up.
• Phelps might not be so eager to shovel down a
  pound of tofu in a sitting, Klion points out.

79
Athletes and Nutrition

• Still, Klion cautions that he knows plenty of
  athletes whove been training for marathons and
  have gained weight because they thought they
  could eat whatever they wanted.
• So it really does take some planning.

80
Athletes and Nutrition

• Normal standards dont really apply to a someone
  like Phelps, who exercises way more vigorously
  than the typical person.
• Even by athletic standards, Phelps is in his own
  league.
• Cyclists in the Tour de France commonly consume a
  paltry 8,000 to 10,000 calories a day.