water and energy balance

Calories, Food, Energy, and Energy

Balance

Calories (review)

• A calorie is a unit of measure of energy• Calories are not a component of food

Our Bodies Needs Energy (calories)

• Body uses energy: to fuel muscular activity for growth for tissue repair and maintenance to chemically process nutrients to maintain body temperature

• Body needs energy in three categories: basal metabolism physical activity dietary thermogenesis

Body Needs Energy• Basal metabolism uses 60-80% of total calories

for: breathing beating of the heart maintenance of body temperature renewal of muscle and bone tissue ongoing activities to sustain life and health

• Growth is component of basal metabolism• Calories for basal metabolism highest during

growing years

Basal Metabolism

• Basal metabolic processes require no conscious effort

• Continuous activities the body performs to sustain life

• Energy needed for basal metabolism is measured when body is in complete physical and emotional rest

How Much Energy for Basal Metabolic Rate (BMR)? 

• Estimate calories for basal metabolism by quick formula*: For men: Multiply body weight in kg by 1 x 24 For women: Multiply body weight in kg by 0.9 x 24

• A man of 77 kg needs 77 x 1 x 24, or 1854 calories per day

• A 77 kg woman needs 61 x 0.9 x 24, or 1663 calories

• Formula estimates basal metabolism for gender and weight

• Other factors affect how efficiently the body uses calories physical activity level muscle mass, height health status genetic traits

• *Results from quick formula may be 10 to 20% lower or higher than the true number required for basal metabolism

How much Energy for Physical Activity?

• Calories needed for physical activity vary according to how active you are

• Usually second highest calories expended• Energy cost of Inactive lifestyle – 30% of calories for basal

metabolism• “Average” activity level requires roughly 50%• “Active” level requires approximately 75%

• Example: Inactive person needing 1500 calories for basal metabolism would require about 450 additional calories for physical activity

• Calculation: 1500 x 0.3 = 450

How many Calories for Thermogenesis?

• Some energy expenditure is for chewing and swallowing foods, digesting foods, absorbing and utilizing nutrients, and transporting nutrients into cells

• Some energy involved in these activities escapes as heat• Processes are dietary thermogenesis • Calories for dietary thermogenesis are about 10% of sum of basal

metabolic and physical activity calories

• Continuing from previous example: basal metabolic needs 1500 calories physical activity needs 450 calories 1500 + 450 calories = 1950 calories calories for dietary thermogenesis equal approximately 10% of 1950

calories, or 195 calories

Adding It All Up • Estimated total daily need for calories is

sum of calories used for basal metabolism, physical activity, and dietary thermogenesis

• In the example, total calorie need is 2145 (1500 + 450 + 195) calories

• Caloric level estimated this way is not exactly accurate, but should be close to total caloric need

How is Caloric Intake Regulated?

• Body mechanisms encourage regular calorie intake• Mechanisms are independent of weight• Encourage eating to sustain body in hard times• Store fat to get through scarcity (advantageous for survival)• Thin or fat, people get hungry through the day• Hunger signals cells have run low on energy• After we eat, we should lose interest in eating• Signal from brain, stomach, liver, fat cells indicate satiety,

feeling that we’ve had enough to eat

Appetite• Hunger and satiety mechanisms adjust intake • Internal signals can be overridden

People resist eating in spite of hunger pains People can go on eating after the “Full” signal

• People may eat due to appetite• Appetite is urge for pleasure of eating• Appetite may or may not be related to hunger• Appetite triggered by smell or sight of food

Energy Balance

• Positive Energy Balance Energy intake is more than need Note that positive energy balance is normal in

growth, or regaining weight lost during an illness

• Negative Energy Balance Energy intake is less than need

• Energy Balance Energy intake equals need

Energy Balance

• Total caloric need to maintain energy balance and weight is affected by:• Smoking• Lean muscle mass • Genetic makeup

• People who smoke use more calories, and muscular individuals need more energy to maintain body weight

Energy Balance• Genes may increase or decrease

calorie need• Small changes in calorie need may not

mean much on a day-to-day basis• But, over a year a consistent positive or

negative daily energy balance of 50 calories could result in a weight gain or loss of five pounds

The Highs and Lows of Body Weight

Body Weight Variations• Regulation of food intake and storage is a very

old genetic trait• Underweight was a distinct disadvantage for our

remote ancestors• Multiple mechanisms for intake and fat storage

were keys to survival• Inborn mechanisms constantly encourage food

intake• Changes in availability of food can explain why

obesity is a major problem• Culture and science define reaction to body size

Body Mass Index • BMI is a measure of weight for height to estimate

body fatness

• Ranges of BMI include: Underweight – under 18.5 kg/m2

Normal weight – 18.5 to 24.9 kg/m2

Overweight – 25 to 30 kg/m2

Obese – over 30 kg/m2

• BMI calculation same for males and females

BMI = [Weight in kg] [height in m]2

The Problem with BMI

• Muscular people can have obese BMI

• Inactive normal BMI people can still have too much body fat

• If people retain fluid BMI may show overweight but body fat may be low

Some Body Fat Needed• 3 to 5% body fat for men and 10 to 12% for women

needed for survival• Body fat essential in manufacture of hormones• A required component of every cell in the body• Provides a cushion for internal organs• Low body fat levels:

delayed physical maturation during adolescence infertility accelerated bone loss problems that accompany starvation

Obesity and Health • Obesity is not a healthy state• Increased risk for:

diabetes hypertension stroke heart disease elevated total cholesterol levels low HDL-cholesterol levels certain types of cancer other health problems

• Life expectancy in overweight/obese adults 3 to 6 years shorter than average

Waist Circumference

• Indicator of health risk associated with excess abdominal fat.

• There is an increased risk of health problems such as type 2 diabetes, heart disease and high blood pressure with a WC 102 cm (40 in.) in men and WC 88 cm (35 in.) in women.

• The following table shows how the BMI and WC combined provide information about health risk.

Normal BMI OverweightBMI Obese

Class I BMI

WC <102 cmWC <88 cm

Least Risk Increased Risk

High Risk

WC >102 cmWC >88 cm

Increased Risk

High Risk Very High Risk

Why Apple is bad

• Fat cells of central fat deposits are larger than those around the hips and “resistant” to insulin

• Decrease ability of insulin to lower blood glucose• Insulin and glucose increase over time• Increased insulin

increases triglyceride levels and blood pressure, reduces levels of HDL

increases risk of hypertension and heart disease promotes the development of diabetes

Diet and Obesity  

• Weight gain if energy in > out Caloric intake up by 340 calories/day Physical activity level remains low We are eating beyond satiety

• inexpensive, calorie-dense foods• eating out• large portions of favorite foods

Activity and Obesity  

• Low activity relates to obesity • Physical activity traded for time,

convenience and has lead to personal fat stores

• TV/screen watching has been blamed for obesity in children and adults

Preventing Obesity (which is different from weight loss) 

• Some adults gain weight at a slow pace and some more quickly, but major gains most likely between the ages of 25 and 34 years

• Regular physical activity (“active living”) may prevent excess weight gain

• Decreasing portion sizes at home and in restaurants may help

• Responding to “I’m full” feeling helps moderate food intake

Underweight • Worldwide, underweight is more common than obesity• Many reasons why people fail to get enough to eat

• Underweight in developed nations results from illnesses such as HIV/AIDS, pneumonia, and cancer; anorexia nervosa; and restriction of food

• Underweight have less than 20% body fat in adult females less than 8% body fat in males

• *Recall what % body fat is needed for survival and compare to that of underweight…

Underweight• BMIs below 18.5 kg/m²• Some people underweight for height have

healthy body composition• Probably they are genetically thin• Naturally thin people can have difficulty gaining

weight• Unless health is compromised (fatigue, frequent

illness, impaired concentration, apathy, or extreme intolerance to cold), there is little reason for concern about underweight

Size Acceptance

• Obsession with body weight spreading • Bias against size contributes to weight problems• Bias lowers self-worth, promotes eating disorders• Females sensitive to attitudes about body size

Although sensitivity in males is increasing• Incidence of obesity higher in males• Obesity in females has more negative stereotypes• Over-reactive parents can make things worse• We must accept that healthy people come in all sizes

Weight Management

• Effective ways to lose weight and keep it off are known

• Many popular methods just lead to a temporary reduction in body weight

• Weight loss plan successful only if safe, healthful, and prevents weight regain

• Known methods work over time for many overweight people

• These lead to small, acceptable, lifetime changes in diet and activity

Successful Weight Losers

• Lose weight slowly – 1 to 2 pounds per week (0.5 – 1 kg per week)

• Make small changes in eating and activity• Eat regular meals – no skipped meals!• Have regular physical activity• Don’t feel deprived when changing habits• Use available sources of social support

Unsuccessful Weight Losers

• Are not committed to a gradual weight loss through behavioral changes

• Change diet radically to lose weight• Have little physical activity• Eat unconsciously in response to stress• Take diet pills• Do not seek out or have social support• Cope with problems by escape and avoidance

Small Changes

• Fat is put on slowly, so that’s best way to take it off

• Rapid changes in body weight actually send signals to the brain that something is wrong

• Gradual losses do not require dramatic changes

Analyze your lifestyle

• Look for weak points in diet: consumption of high-fat foods relying on high-fat convenience foods skipping breakfast and overeating later

• Look for weak points in physical activity: driving instead of walking not engaging in sports spending too little time playing outside

Managing your Eating

• Protein foods helps prevent overeating helps curb hunger boosts your calorie burning power

• Calcium foods Burns harmful abdominal fat Helps store less body fat Effect more significant when the calcium

comes from Milk and Alternatives

Try the Plate Method

• Start with a 9-inch “luncheon” plate• ½ vegetables• ¼ protein food• ¼ starchy food• On the side:• 1 serving milk or alternative• 1 serving fruit

Weight Loss Expectations

• Weight loss gradual but lasting• Pattern will include peaks, valleys, and

plateaus• Enjoy and continue improved eating and

activity patterns• Improved patterns offer many mental and

physical benefits; weight loss is only one of them

Let’s Review

• Which of the following activities is not a function of basal metabolism?

a. Body temperatureb. Brain activityc. Growth and tissue repaird. Walking

• All of the following are included in the measure of physical activity except:

a. walking.b. standing.c. dreaming.d. eating.

• Which of the following people is in negative energy balance?

a. A pregnant womanb. A person who is regaining weight lost

during an illnessc. A growing childd. A person who is fasting

• Which of the following areas of body fat storage is associated with metabolic syndrome?

a. Upper armsb. Thighsc. Abdomend. Hipse. All are equally associated with health risks.

Water

Water

• Water needs – men – 3.7 litres per day women – 2.7 litres per day

• Only live six days without water • Largest component of diet and body• Basic requirement of all living things

Foods Contain Water

• Beverages are 85% water• Fruits and vegetables 75 to 90%• Meats are 50 and 70%• Fats and oils contain little to no water• Water in foods contributes to our intakes

80% of total fluid intake from beverages 20% from foods we eat

Health Benefits

• 10 cups (2.5 litres) each day associated with decreased risk of Bladder Breast Colon cancer Kidney stone formation

• People feel and perform better when adequately hydrated

“Gourmet” Water

• “mineral,” “spring,” and “seltzer” waters have strong image

• Mineral water from underground reservoirs and contains more minerals

• Spring water from freshwater springs on the surface

• Seltzers are naturally carbonated with CO2

Bottled Water

• Calorie-free• Can be sodium-free or low in

sodium• Quenches thirst better than

soft drinks• Not purer than tap water

Need for Water

• Individuals require enough water to replace water lost in urine, perspiration, stools, and exhaled air

• Built-in thirst mechanisms protect people from too much or too little Perceptual triggers – e.g. thirst sensation Physiological triggers – e.g. change in blood

volume

Need for Water - Athletes

• Athletes have higher body water values due to increased muscle mass and less body fat

• 2-3 hours before exercise – 400 to 600 mL fluids• During exercise – 150 to 350 mL fluids every 15

minutes• After exercise – 450 to 675 mL fluids for every

0.5 kg body weight lost during exercise

Special Needs

• Hot weather increases water need• Prolonged vomiting, diarrhea, and fever increase

water need• High-protein and high-fiber diets, and alcohol

use, increase water need high protein consumption causes losses, people on

high-protein diets drink extra water fiber increases water loss in stools increased loss of water with alcohol intake

Water Deficiency• Deficiency of water leads to dehydration• Dehydrated people feel very sick:

nauseated fast heart rate increased body temperature feel dizzy find it hard to move Headache Decreased mental alertness Dark, scant urine

• Fluids produce quick recovery• Dehydration can lead to kidney failure and death

Water Toxicity• People can overdose on water• High intake leads to:

hyponatremia -or low blood sodium level excessive water accumulation in the brain and lungs consequences of confusion, severe headache, nausea,

vomiting, seizure, coma, and death• Water intoxication occurred in:

marathon runners who consumed too much water during an event

infants given too much water or over-diluted formula psychotic patients taking medications that produce

cravings for water

Fluid intake and weight management

• To avoid consuming too many calories from beverages, limit drinks to 10% of total calorie intake E.g. in a 2000 calorie diet, you would

consume only 200 calories worth of drinks other than water

• What are some ways the body loses water daily?

a. perspirationb. stoolsc. exhalationd. urinee. all of the above

• All of the following are symptoms of dehydration except:

a. weakness.b. nausea.c. dizzy.d. hunger.e. difficulty moving.

• Which of the following foods provides the least amount of water?

a. soft drinksb. fruitsc. vegetablesd. milke. well-done meat

• Which of the following people needs to increase his or her fluid consumption?

a. A person that has over consumed alcoholb. A person exercising at high altitudesc. A person exercising at sea leveld. A person exercising in a cold environmente. All of the above