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Nutritional Factors. Influencing Body Composition. 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. Nutrition and Exercise.

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nutritional factors

Nutritional Factors

Influencing Body Composition

overconsumption
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.
nutrition and exercise

Nutrition and Exercise

Where do we get the energy for movement?

What should we eat to insure optimal health and fitness?

nutrition and exercise1
Nutrition and Exercise
  • Energy for movement comes from the food we eat.
  • The three sources of energy are:
    • Carbohydrates
    • Fats
    • Proteins
nutrition and exercise2
Nutrition and Exercise

General Recommendations:

  • CHO 55-65%
    • CNS
    • Primary fuel source
    • Only anaerobic fuel source
    • Required for fat metabolism
    • Required for protein metabolism
nutrition and exercise3
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
nutrition and exercise4
Nutrition and Exercise
  • Fat
    • High in kcal per weight
    • Low fat = <20%
    • 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)
nutrition and exercise5
Nutrition and Exercise
  • Protein 10-15%
    • Growth and maintenance of lean tissue
    • Repair of damaged tissue
    • Fuel source during starvation
food guide pyramid
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
food guide pyramid1
Food Guide Pyramid

www.mypyramid.gov

nutrients
Nutrients
  • CHO
  • Fat
  • Protein
  • Water
  • Vitamins
  • Minerals
vitamins
Vitamins
  • Fat Soluble
    • A D E K
  • Water Soluble
    • B Complex
    • C
free radicals and antioxidants
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 β-carotene) can trap free radicals and prevent this action.
minerals
Minerals
  • Calcium
  • Phosphorus
  • Magnesium
  • Iron
  • Potassium
  • Sodium
calcium
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.
slide17
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.
slide18
Zinc
  • RDA = 11 mg for men, 8 for women
  • Upper limit = 40 mg
  • More can block absorption of another vital nutrient, copper.
water
Water
  • Important before, during, and after physical activity.
  • 2.5 liters per day.
  • Major factor limiting exercise performance.
  • Thirst.
dieting
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.
yo yo dieting
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 don’t add bone or muscle mass.
fad diets
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.
low carb
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”
low carb1
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.
low carb2
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.
low carb3
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.
low carb4
Low Carb
  • August 1st, 2005 Atkins Nutritionals declares bankruptcy
body composition questions
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.
body composition questions1
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.
body composition questions2
Body Composition Questions
  • The weight is regained rapidly, however, when CHO intake returns to normal.
protein power
Protein Power
  • 850-1,100 kcal/d
  • High protein
the zone
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
sugar busters
Sugar Busters!
  • 1,200 kcal/d with 28% of total energy intake from fat
  • 33% of total energy intake from protein
south beach diet
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
nutrition questions
Nutrition Questions
  • Why are low carbohydrate diets unsafe?
  • Low CHO intake may lead to fatigue, hypoglycemia, and ketosis.
nutrition questions1
Nutrition Questions
  • Low carb diets are detrimental to anaerobic work capacity because of reduced muscle glycogen stores and decreased rate of glycolysis.
nutrition questions2
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.
nutrition questions3
Nutrition Questions
  • Low carb diets are high in fat, saturated fat, and cholesterol.
nutrition questions4
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.
nutrition and exercise6
Nutrition and Exercise
  • Do we need to consume large amounts of protein if we exercise and wish to increase muscle mass?
nutrition and exercise7
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

nutrition and exercise8
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
nutrition and exercise9
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
nutrition and exercise10
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.
amino acids and protein
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)
amino acids and protein1
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)
amino acids and protein2
Amino Acids and Protein
  • Supplementation of the athlete’s diet with branched-chain amino acids apparently does not benefit exercise performance.
    • (Gibala; Hargreaves, and Tipton, 2000)
amino acids and protein3
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)
amino acids and protein4
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)
amino acids and protein5
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)
nutrition questions5
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.
nutrition questions6
Nutrition Questions
  • Excessive protein intake does not promote protein synthesis.
  • Instead the excess protein is metabolized.
nutrition questions7
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.
nutrition questions8
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.
nutrition questions9
Nutrition Questions
  • Dehydration and the additional stress placed on the kidneys may be potentially dangerous, especially for individuals with kidney problems or gout.
nutrition questions10
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.
nutrition questions11
Nutrition Questions
  • Are high-fat diets unsafe?
  • Yes
  • They produce high levels of serum cholesterol and triglycerides which may lead to atherosclerosis.
nutrition questions12
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.
nutrition questions13
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.
nutrition questions14
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.
nutrition questions15
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.
nutrition questions16
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 body’s protein (protein-sparing effect).
nutrition questions17
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.
nutrition questions18
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.
nutrition questions19
Nutrition Questions
  • This results in the incomplete breakdown of lipids and the formation of ketone bodies that may cause ketosis.
nutrition questions20
Nutrition Questions
  • In addition, muscle glycogen and glucose are the primary fuels used during intense, short-term exercise and prolonged, submaximal exercise.
nutrition questions21
Nutrition Questions
  • Inclusion of adequate amounts of CHO in the diet prevents depletion of muscle glycogen and the consequent reduction in endurance performance.
sugared drinks
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
sugared drinks1
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
sugared drinks2
Sugared Drinks
  • Low levels of sugar-sweetened drink intake does not increases weight gain or diabetes over time.
athletes and nutrition
Athletes and Nutrition

Swimmer Michael Phelps’s 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, he’s got to be setting new marks on the chow line.

A New York Post account of Phelps’s… wait for it… 12,000-calorie-a-day diet, gave us a stomachache.

athletes and nutrition1
Athletes and Nutrition

Could one human being really consume that much and still be in Phelps’s shape?

And could this possibly be healthy for Phelps, even considering his five-hours-a-day, six-days-a-week exercise regimen?

athletes and nutrition2
Athletes and Nutrition

Here’s Phelps’s typical menu.

No, he doesn’t 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.

athletes and nutrition3
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.

athletes and nutrition4
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.

athletes and nutrition5
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 he’s burned.

If he doesn’t, his “body won’t recover, the muscles will not recover, there will not be adequate energy stored for him to compete in his next event.”

athletes and nutrition6
Athletes and Nutrition

But what about the choice of foods?

All those eggs and ham and cheese can’t possibly be good for him, can they?

athletes and nutrition7
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 you’ve got to eat that much, it better be enjoyable, or you won’t be able to keep up.

Phelps might not be so eager to shovel down a pound of tofu in a sitting, Klion points out.

athletes and nutrition8
Athletes and Nutrition

Still, Klion cautions that he knows plenty of athletes who’ve been training for marathons and have gained weight because they thought they could eat whatever they wanted.

So it really does take some planning.

athletes and nutrition9
Athletes and Nutrition

Normal standards don’t 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.