Anatomy & Physiology Nutrition

Nutrition & Nutrients Nutrition: The science of the modification, absorption and utilization of food substances by the body Essential nutrient: must be supplemented in the diet for the body’s use There are 6 different classes of nutrients

Nutrients: Carbohydrates Provide 4 kcal/gm. of energy The body’s most efficient source of energy Preferred fuel for cellular energy (ATP) Should account for 55-70% of diet

Nutrients: Carbohydrates Derived from plants Polysaccharides: complex carbs/starches Legumes, root vegies, whole grain Digested into simple sugars Part of plant indigestible by humans = FIBER Fiber aids defecation; binds to cholesterol, preventing its absorption Monosaccharides: Disaccharide Fructose: sugar from fruits Sucrose: table sugar Glucose Lactose: sugar from milk

Nutrients: Fats Provide 9 kcal/gm. of energy Essential to the diet Should account for 20-30% of diet (10% saturated) Used in the body for: Energy Growth and development Synthesis of plasma membranes, steroid hormones, myelin sheaths, fatty cushions

Nutrients: Fats Fats in excess: Stored in fat depots Hips, breasts, abdomen, and subcutaneous tissues Average American intake of fat: 40-50% of total calories Leads to obesity, type II diabetes, coronary heart disease, certain cancers

Nutrients: Fats Types of triglycerides: Unsaturated fats: liquid at room temperature Plant products: nuts, vegetable oils, seeds Saturated fats: solid at room temperature Animal products: meats and dairy Should account for less than 10% of fat calories daily

Nutrients: Fats Cholesterol: made in the body Non-essential (don’t eat!!) Found only in animal products (meat, dairy) Recommended allowance less than 300 mg/day Function: steroid hormones, plasma membranes, NOT FOR ENERGY

Nutrition: Fats Cholesterol (like all fatty acids) are insoluble in water (plasma), therefore are transported in the blood via lipoproteins LDL low density lipoprotein BAD lipoprotein Transports cholesterol TO body cells Can be deposited into arterial walls if in excess in blood stream HDL: high density lipoprotein GOOD cholesterol Transports cholesterol to liver for disposal in bile Will EXIT the body

Nutrition: Proteins Provide 4 kcal/gm. of energy Needed for growth, maintenance and repair NOT an energy source unless in dire need Should account for 12-15% of daily calories Incomplete proteins: plant sources; beans, nuts Complete proteins: animal sources; meats, cheeses, nuts

Nutrition: Vitamins Organic compounds that are required in small amounts for growth and good health Act as coenzymes by assisting the regulation of physiological processes Fat soluble vitamins: ADE & K: absorbed and stored in fats Can be toxic in excess Water-soluble vitamins: B-complex and C Not stored; excreted

Nutrients: Minerals Inorganic molecules ingested with organic components of food There are more than 20—all must be supplemented Eating a wide variety of foods is the best way to obtain all essential minerals (and vitamins too!!) Examples: calcium, phosphorus, zinc, iron, etc.

Nutrients: Water The most essential of all nutrients Most abundant nutrient in the body; accounts for 60% of body weight Average adult needs ~2.5 liters/day; roughly 8-8 oz. glasses/day Water is essential for: All chemical reactions Energy production Normal digestion Temperature control Waste elimination

RDA: Recommended Daily Allowance Designed by gov’t agency to help people compare nutritional value of many food products Started because of American’s poor diets Based on a 2000 calorie diet

Body Composition A comparison of fat percentage to lean body mass percentage Provides accurate information about how mush weight can be gained or lost Body Fat Percentage: the portion of total body weight that is composed of fat tissue Lean Body Weight: the portion of total body weight composed of lean tissue Muscles, tendons, bones, connective tissue

Body Composition Females Males Avg. college-aged 20-25% 12-15% Endurance Athletes 14-20% 8-12% Should not go below 12% 3% Clinically obese 30+% 25+%

Body Energy Balance & Weight Loss Caloric Balance = # cals. consumed - # cals. expended Regardless of whether calories come from fat, protein, carbs or alcohol! Weight gain = consumption > expenditure Weight loss = consumption < expenditure

How Do We Control Food Intake? It’s unknown for sure! But we do know…nutrient levels, hormones, body temperature & psycological factors all have an effects on eating behaviors You have to get to know your own body and your own behaviors

BMR: Basal Metabolic Rate The amount of heat energy produced by the body at rest The energy supply needed to breathe, maintain a heartbeat, kidney functions…all vital activities!

BMR: Basal Metabolic Rate Influenced by many factors: Thin > heavy Male > female Older < younger Strong emotions raise BMR Thyroxine production high > low production

Metabolism The sum total of the chemical reactions that occur in the body; everything that is broken down and built up Catabolism: breaking down substances into simpler substances Protein to amino acids Anabolism: simpler substances combine to form complex substances Glycerol + fatty acids = triglycerides

Methods of Weight Loss Dieting Exercise Difficult and ineffective Long term weight control is successful only 2% of the time 35-45% of wt. loss is lean tissue (not fat) Minimum caloric intake should never go below: Females: 1000-1200 C Males: 1200-1400 C Exercise 80-90% loss of fat tissue without loss of lean tissue Still very difficult Extra benefits: Cardio-respiratory endurance Strength Flexibility

Methods of Weight Loss Diet & Exercise The most effective way to lower body fat percentage! Moderate caloric restriction + moderate increase in caloric expenditure = negative caloric balance Recommended HEALTHY weight loss 1.5-2 lbs. /week 3500 C = 1 pound of fat IF YOU Ate 200 less calories / day + burned 300 extra calories /day 500 total calories lost X 7 days/week = 3500 C