Chapter 25

Metabolism and Nutrition

INTRODUCTION

• The food we eat is our only source of energy for performing biological work.

• Food molecules are used 3 ways:– To supply energy– To serve as building blocks for proteins, enzymes,

hormones– Stored for future use

METABOLIC REACTIONS

• Metabolism refers to all the chemical reactions in the body.• Catabolism is the breakdown of complex molecules to

simpler ones• Anabolism is the manufacture of larger molecules from

simpler ones• All chemical reactions require ATP.

The Molecules of Life

• Food is composed of 4 molecules:– Carbohydrates*– Lipids*– Proteins*– Nucleic Acids

CARBOHYDRATE METABOLISM

• Carbohydrates are absorbed by the SI and converted to glucose by the liver

• Glucose is used to:– Make ATP (the most of all molecules)– Make amino acids and proteins– Make glycogen (stores energy)– Make triglycerides (stores energy)

Lipid Metabolism

• Lipids are absorbed by the SI and transported in the blood.• Our body needs lipids to:

– Make ATP– Store energy– Make cell membranes– Form myelin sheaths– Insulation– Repair bones– Form hormones– Include: Vitamins A, D,E, and K, carotene

PROTEIN METABOLISM

• Proteins are broken down to amino acids, absorbed by the SI, and transported to the liver.

• They are used:– To Make ATP– To help the body grow and repair itself– As enzymes– For transportation and communication in the body– As antibodies– Hormones, muscles, bones, and skin all need proteins to

function

Metabolism

• It takes 4 hours to digest an average meal• The body spends about 12 hours per day absorbing

nutrients from the food we eat.• Hormones (secreted by the thyroid gland) regulate our

metabolic rates• This requires energy, or calories, and the average person

spends 1200-1800 calories per day just to maintain normal body function.

NUTRITION

• Nutrients are chemical substances in food that body cells use for growth, maintenance, and repair.

• We need 6 nutrients daily:– Water– Carbohydrates– Lipids– Proteins– Minerals– Vitamins

Guidelines for Healthy Eating

• Eat a variety of foods• Maintain a healthy weight• Choose foods low in fat, saturated fat, cholesterol, and

sodium• Eat plenty of fruits, veggies, and whole grains• Use sugar in moderation• Use salt and sodium in moderation (less than 1 tsp daily)• Don’t drink alcohol, or not more than 1 ounce daily

Calories

• A calorie is the amount of energy required to raise 1 gram (or 1 mL) of water 1 degree Celsius.

• When eating, a calorie is the measure of the amount of ATP we can make from the food we eat.

• To lose maintain current weight:– Women need 1800-2000 calories– Men need 2200-2800 calories

• To lose weight:– Women 1200-1800 calories– Men need 1800-2200 calories– *Remember, our body naturally uses 1200-1800 calories

daily (not including exercise)

Calories

• Each gram of protein or carbohydrates provides 4 calories of energy, each gram of fat provides 9 calories of energy.

• A normal diet consists of:– 50-60% carbohydrates– 30% fat– 12-15% protein

Good vs. Bad Carbohydrates

• Bad carbs:– Soda– White bread, pasta, rice, potatoes– Sugar: soda, cake, pastry

• Good carbs:– Fruit: apples, berries, citrus– Vegetables: sweet potato, leafy greens– Brown rice– Whole grain Pasta– Oats

Essential Fats

• Without enough fat, you might see: dry skin, slow metabolism, moodiness, decreased energy, dizziness, and memory loss.

• Bad Fats

– Transfat (in fried foods-even bagels, margarine, crackers, cookies)

– High Fructose Corn Syrup (in everything)

– Red meat (lamb, beef)

• Good Fats

– Vegetable oils (olive, grape seed, sesame, avocado)

– Fish and lean meat (chicken, turkey)

– Nuts

– Dairy

Protein

• Good sources of protein include:– Lean meats: chicken, turkey, fish– Eggs– Cottage cheese– Low fat dairy– Nuts– Beans– Spinach and other leafy greens– Whole grains (brown rice, barley)– Tofu– Lentils

Water

• Our bodies are 70% water• We use it for energy, detoxification, regulation of body

temperature, making cells, lubricating joints, etc.• Drinking caffeine or alcohol dehydrates our cells• Our body uses 10 cups of water per day (80 ounces)• If you only drink when you are thirsty, you’re not drinking

enough• Urine should be clear or very very pale yellow

Minerals• Inorganic substances = 4% body weight• We need many minerals, including Ca, P, K, S, Na, Cl,

Mg, Fe, I, Mn, Cu, Co, Zn, F, Se, and Cr• Functions

– Make bone– Make enzymes– Used in ATP production– Control pH– Help send nerve impulses

Vitamins

• Vitamins are organic nutrients that maintain growth and normal metabolism, and function as enzymes.

• Fat-soluble vitamins are stored in the liver. A, D, E, and K are fat-soluble.

• Water-soluble vitamins excreted in urine when in excess. The body does not store water-soluble vitamins well. Includes the B and C vitamins.

FOOD: What you need

• Calories IN < calories OUT = lose weight• Calories IN > calories OUT = gain weight• BMI = Body mass index• It is a measure of healthy weight• ((Weight in pounds / height in inches) / height) x703• 25 30 is overweight• More than 30 is obese• Less than 17 is unhealthy• Goal is to be between 18.5 and 25• Out of the range increases risk of cancer, heart disease,

diabetes, stroke, bone injuries, early death

BMI

Examples of Healthy Meals

• Breakfast: 1 serving fruit, 1 serving protein, 1 serving carbs• Lunch: 1-2 servings fruit, 1 serving veggie, 1 serving protein,

1 serving carb• Dinner: 1 protein, 2 veggies, 1 carb, 1 fruit• Snacks: Fruit, nuts, whole grains

• Portion size: – Fruit: 1 apple– Protein: size of your palm– Carb: size of your clenched fist (small potato)– Veggie: 1 cup

Drinks

• Water is the best• Fruit juices and sodas have sugar and calories• Caffeinated beverages dehydrate the body• Alcohol dehydrates the body and adds extra calories to your

diet• There are health benefits to drinking caffeine (green tea)

and alcohol (red wine) occasionally, in small amounts – but don’t start if you aren’t currently!

Food, continued...

• Things to be aware of:– Sodium– High Fructose Corn Syrup– Trans Fat– Cholesterol– Palm Oil– Sugar

Sodium

• The average American consumes 1 ½ teaspoons a day, or 4400 mg

• Our body needs 1500 mg• Excess sodium leads to increased blood pressure and heart

attacks• Salt shakers are responsible for only 11% of our salt intake• It comes from packaged foods, including:

– Crackers, pretzels, chips, soda– Meat– Cereal– TV dinners– Candy

High Fructose Corn Syrup

• Is in everything from drinks to crackers to yogurt to candy to pizza sauce to salad dressing...it is found in every aisle of the grocery store

• Contributes to high blood pressure, diabetes, and obesity• Cutting out all soda can reduce your intake

Trans Fat

• Increases coronary artery disease, cholesterol, Alzheimer’s, cancer, diabetes, obesity, liver disease, and infertility

• They are not needed by our body in any way• Banned in most EU countries, and limited in NY• Most fast food companies are in the process of switching

away from trans fats

Cholesterol

• Cholesterol is needed by the body to make cell membranes• Mostly found in dairy, meat, seeds, and nuts• Too much cholesterol can lead to heart disease• Not enough can cause cancer and depression

Palm Oil

• Found in foods and cosmetic products, including Girl Scout Cookies

• It’s a saturated fat, and is less healthy than other vegetable oils

• Harvesting destroys rain forests in SE Asia, increases carbon dioxide output and global warming, increases pollution, and kills orangutans

Sugar

• Sugar is found as table sugar (sucrose), in fruit (fructose), in dairy (lactose), and in carbohydrates (glucose).

• Too much sugar can cause diabetes and obesity (empty calories)

• Long term effects of sugar substitutes are unknown• Limit sugar intake, and use honey or agave nectar instead

Food that’s Good

• Good food provides you with energy, promotes good moods, and prevents disease. Include in your diet:– Blueberries: reduces cancer; improves memory,

intelligence, coordination; provides fiber and vitamins A, C, and E

– Black Beans: reduces heart disease, cancer, birth defects; provides vitamins and minerals

– Sweet Potatoes: full of vitamins and minerals; good for diabetics; boost immune system; lowers cholesterol

– Oats: Contains fiber and protein; reduces cholesterol; stabilizes blood sugar; reduces heart disease

Food that’s good

– Salmon: has omega-3 fatty acids; vitamins A and B; protein and calcium; lowers cholesterol and heart disease; fights arthritis and stroke; lowers blood pressure

– Spinach: has lots of vitamins; protects against cancer; reduces strokes; has iron, calcium, and zinc

– Broccoli: fights cancer; helps eyes, kills bacteria, high in fiber, vitamins, minerals

– Tomatoes: reduces cancer (breast, prostate) and signs of aging (lycopene); has vitamins A and C and potassium; protects against heart disease

Food that’s good

– Chocolate: contains calcium; decreases cholesterol; has antioxidants; increases good mood

– Walnuts: fights cancer; reduces cholesterol; combats depression; reduces heart attacks; contains protein and fiber

– Soy: good source of protein; reduces cholesterol; reduces blood pressure; maintains bone strength; fights cancer and diabetes; contains vitamins and minerals

– Onions: contains vitamin C and calcium; combats heart disease and cholesterol; protects against cancer, asthma, and ulcers; promotes bone strength

Diet Options

• We will discuss– Organic food– Vegetarians, vegans– Atkins– Zone– South Beach– Mediterranean– Cleanses

Organic

• Organic food is free of chemicals, including: pesticide, herbicide, fertilizer, antibiotics, food additives, and is not genetically modified

• Benefits include:– Better tasting food (?)– More vitamins and minerals (?)– Improved food safety– No hormones or antibiotics– Better animal care and treatment– Less pollution, better for the environment

Veggies

• Vegetarians do not eat meat (beef, chicken, turkey, pork, fish, etc.)

• Pescetarians do not eat meat, but do eat fish/seafood• Vegans do not eat any animal products (meat, dairy, honey,

eggs)• Benefits include:

– Lower cholesterol, blood pressure, and BMI– Longer life spans– Less heart disease and cancer– Better for animals and the environment– Must monitor vitamin B12 intake (also iron, calcium

vitamin D, and iodine)

Atkins

• This diet is low-carbohydrate, intended to reduce weight• Some consequences include:

– Reduced weight (temporary)– Possible increased cholesterol, blood pressure, and heart

disease– Increased osteoporosis and kidney stones– Can cause diarrhea, weakness, and muscle cramps

The Zone

• Advocates consuming 40% carbs: 30% fats: 30% protein• Can result in:

– Weight loss– Fatigue– Hunger– Too much protein can raise cholesterol and heart disease

South Beach Diet

• This is a low fat diet, which can result in:– Weight loss– Emphasizes fruits, veggies, and whole grains– No long term studies have been done on this type of diet,

but it is said to reduce heart disease and cholesterol

Mediterranean Diet

• This emphasizes the diet eaten in Greece, which is low in red meat and fats, and high in yogurt, olive oil, fish, beans, and grains.

• Consequences include:– Healthy fat intake, increase fruits and veggies– Low cholesterol– Lower heart disease– Improved immune systems– Lower cancer

“Cleanses”

• Objective is to rid the body of toxins• Usually eliminate all processed foods• Consequences include:

– Weight loss– Hunger– Fatigue– Improved skin and bowel functions– Improved immune system– IF done for a limited time (less than a week, once a year)

may have benefits

Exercise

• 30 minutes of vigorous cardiovascular exercise is recommend 5-7 days per week

• Weight training (free weights, sit ups, yoga, pilates) should be done 3 times per week

• Benefits your heart, lungs, mind, skin, all body systems• Decreases cancer, heart disease, stroke• Increases life span

To conclude

• Maintain a healthy BMI by:– Eating good foods, like fruits, veggies, and whole grains– Avoiding processed foods, sodium, fat and sugar– Monitoring intake of calories (expend more than you take

in)– Drinking enough water– Getting daily exercise

Diseases and Disorders...

• Acidosis: abnormally low blood pH caused by diets high in fat. Can result in coma or death.

• Phenylketonuria (PKU): genetic disease in which there is too much of the amino acid phenylalanine in the blood. Results in vomiting, rashes, seizures, and mental retardation.

• Emotional Eating: eating in response to emotional drives such as stress, boredom, anger, or fatigue. Can lead to high blood pressure, obesity, heart disease.

• Hypervitaminosis: too many vitamins are stored in the liver; can cause weakness, headaches, vomiting, pain, coma, death.

• Hypovitaminosis: vitamin deficiency, can cause a variety of sypmtoms

Diseases and Disorders...

• Obesity: body weight more than 20% above standard due to excess fat. Results in C-V disease, high BP, diabetes, arthritis, cancer, GI diseases, early death.

• Diabetes: high blood sugar and not enough insulin produced by the pancreas.– Type 1: the body doesn’t make enough insulin (genetic)– Type 2: cells don’t use insulin properly (lifestyle)

Food Log Directions

• Starting right now, and for the next 2 weeks, keep a record of:– Everything you EAT or DRINK– Any EXERCISE that you do, including PE (must be at least 30

minutes and raise your heart rate)

– For all food and drink, record the calories you’ve eaten. This might be on the package, or you might need to look it up on line

– Resources: – Google: Calorie King– Mynetdiary.com– *I will be checking in your food log EVERY CLASS period from now

until next Friday (5/6) when it’s due!*