nutrition unit 4

The Kilocalorie (kcal)

• the unit used to measure the energy in foods

• It is the amount of  heat energy needed to raise the temperature of 1 kilogram of water by 1 degree Celsius

Recommended % of Daily Energy for carbs

55% of energy

Recommended % of Daily Energy as lipids/fats

30% or less

• No more than 10% saturated fat

Recommended % of Daily Energy protein

10-15%

The 3 Ways the Body Spends Energy

1. basal metabolism (largest part, involuntary)

2. physical activity (most controllable &second largest)

3. thermic effect of food (energy to digest, absorb, & process food)

Basal Metabolism 

• The sum total of all the involuntary activities  needed to sustain life: circulation, breathing, temperature, hormones, nerves, new tissue

  • Excludes digestion and voluntary activity

• the largest component  of the average person's daily energy use

• Usually  50–65%  of daily calories

•  Measured at complete physical & emotional rest, fasting, in a warm room 

what hormone controls basal metabolism

thyroxine

physical activity

• Accounts for the second highest amount of calories we spend

• The  heavier the weight of the body parts moved and the longer the time spent , the more calories you spend

thermic effect of food

• The body's response to food uses about 5–10% of a meal's energy in stepped-up metabolism in the  five hours after the meal 

• Energy for digesting, absorbing, using and moving nutrients into cells; some escapes as heat

Factors That Affect BMR

• age

• height

• growth & body composition

• fever

• stress

• environmental tempurature

• Fasting / starvation: lowers BMR

• Malnutrition:  lowers BMR 

• Thyroxine: key regulator; more hormone = higher BMR

• Physical activity: more lean tissue can raise BMR

• Recovering from a disease

•  Genetics 

• Caffeine & smoking:  increase BMR 

• Before menstruation: increases (hormones)

Standards for body weight are based on

• disease risk and length of life

obesity is mainly based on

body fat content

Underweight, normal & overweight are defined by

weight-for-height,

 BMI: Body Mass Index 

• Defines average  relative weight for height  in people older than 20; correlates with body fat & disease risk

• Does not measure body composition or  the distribution of fat 

Anthropometry

• Fatfold test with calipers by a trained technician: accurate total fat, fair location

• Waist circumference shows visceral fat; risk rises even when BMI is normal

Ways to Measure Body Fat: Density

Ways to Measure Body Fat: Conductivity

• Bioelectrical impedance: a tiny current passes through lean tissue & water

•  Changes in body water (hydration)  can affect results

Ways to Measure Body Fat: Radiographic (DEXA)

• Two x-ray beams measure total fat, fat distribution & bone density

• The most accurate

amount of body  fat essential for women

10-12 %

amount of body  fat essential for men

3-5 %

Gaining fat in women

•  buttocks & thighs (gluteofemoral) = "pear"

Gaining fat in men

• abdomen = "apple"

Losing fat

The last place to gain is the first to lose; the first place to gain is the last to lose

Ideal Body Fat: What Best Supports Health in men

12-20 %

Ideal Body Fat: What Best Supports Health in women

•  20–30%  of weight as fat

Hunger: The "Go" Signal theory

• Eating is regulated by "go" signals (start eating) and "stop" signals (cease eating)

• Hunger: felt 4–6 hours after eating; triggered by an empty stomach & intestine, the hormone ghrelin, and brain signals

• The stomach  stretches and adapts to the amount of food you usually eat ; may explain rising obesity as serving sizes grew

Appetite & Satiety theory

• the psychological desire to eat; learned, triggered by sight, smell or thought of food

•  Endorphins released in the brain stimulate appetite 

• Satiety: feeling of fullness that halts eating until the next meal

•  Hunger strongly stimulates eating, whereas satiation is weaker and can be ignored 

• Leptin: a satiety hormone  produced by adipose (fat) tissue 

• Protein is the most satiating; foods high in fibre, water or air also increase satiety

Metabolic Theories

• differences in how bodies regulate and spend energy make some people store fat more easily 

 Set point theory

• It suggests your body has a preferred weight range or biological baseline that it actively tries to maintain

Thermogenesis theory

• production of heat; some energy is "wasted" as heat

white fat

stores energy, slow metabolism

brown fat

•  releases energy as heat

• is more active in lean animals; fat cells of obese people may burn less energy

genetics theory

• Affects how efficiently we use or store energy

External cues theory

•  people overconsume when offered delicious foods 

• Moods, comfort foods, time of day, stress

Availability, price & ads theory

High-calorie fast food is cheap, everywhere & heavily advertised

physical activity theory

• Some people move too little rather than eat too much

Central Obesity: Visceral Fat is dangerous for

diabetes, stroke, hypertension and coronary artery disease 

Smokers  may carry more of their body fat

centrally

Central obesity is higher

with more alcohol

Central obesity is lower

with more physical activity

or each  3500 cal  you eat in excess, you store about  

1 lb of fat

 1–2 lb per week

can be lost saftly

 diet should not recommend less than

• 1000–1200 cal per day  

Ways to Lose Weight

increase output - physical activity

decrease input - less eating

 right after a workout, appetite is

•  suppressed by  circulating lipids & glucose released from storage to fuel exercise 

• Metabolism stays slightly raised for several hours after exercise

If lean tissue keeps being used for fuel, death would occur in

about 10 days

ketone bodies

acidic compounds made from fat & some amino acids. Normally rare in blood, they  help feed the brain when too little carbohydrate is available, sparing tissue protein

Ketosis

can upset the blood's acid-base balance and cause mineral losses in urine

A moderately restricted diet gives

• faster fat loss & keeps more lean tissue than a severe fast

Low cancer rates correlate with intakes of

•   fibre-rich fruits, vegetables & whole grains (especially whole wheat) 

When calorie intakes rise,

cancer rates rise; excess calories from CHO, protein & fat all raise cancer rates 

Obesity is a risk factor for

colon, breast, endometrial, kidney & esophageal cancer

cancer risk rises with

BMI

More adipose tissue → more estrogen =

higher breast cancer risk

behaviour modification for healthy weight loss

lifelong habits, self-monitoring, cue control

High-protein diets

 Not recommended: they restrict healthful foods, risking low vitamin & mineral intake and heart, kidney, bone & liver problems

examples of fad diets

• Very low-carb / keto & Atkins-style diets

• Single-food diets (cabbage soup, grapefruit)

• Juice cleanses & "detox" teas

• Very low-calorie liquid fasts

• Blood-type diets

drugs and sugery for weight loss

they may save the lives of obese people at critical risk, but they carry serious risks—drugs can cause side effects like heart attack, stroke, and liver damage, while surgery can cause infection, dehydration, and nutritional deficiencies.

why are natural herbs harmful

many contain toxins

Dieter's teas (herbal laxatives)

• only a temporary 1–2 lb water loss; nausea, vomiting, diarrhea, cramps, fainting; suspected in 4 deaths

eating disorders start  during

adolesence

Female athlete triad

disordered eating, amenorrhea, osteoporosis (now part of RED-S, relative energy deficiency in sport)

anerexia Usually begins around

puberty

Anorexia Nervosa

•  A powerful desire to take control of life and feel competent, by controlling eating & weight 

• obsessive desire to be thinner

behaviours of anorexia

•  Often perfectionist 

•  Rejecting food is a way of gaining control 

•  Tremendous discipline   ·  Deny hunger

•  Obsessive about the calorie content of foods 

• Extreme exercise  ·  Laxatives

•  Need for self-control dominates other needs

Binge stages for bulimia

• anticipation → anxiety → rapid, uncontrolled eating → relief → shame or disgust

• Then may use laxatives or induce vomiting

Vomiting irritates the

pharynx, esophagus & salivary glands; causes tooth erosion and dental caries

binge eating disorder is Eating excessive amounts of food at one time, for two reasons:

•  1. Very hungry from dieting or restricting; the binge is a response to hunger 

•  2. Overeating to comfort themselves, avoid situations or numb feelings

• Do not usually compensate (no vomiting, fasting, over-exercising or laxatives)

clinical eating disorder

• anorexia nervosa, binge eating disorder, bulimia nervosa, ED-NOS

disordered eating

includes a  wide range of abnormal eating behaviours : restrained eating, compulsive eating, habitual dieting, chaotic eating; hunger & fullness ignored

ED-NOS is

a mix of symptoms that doesn't fit one category (e.g., all signs of anorexia but still menstruating or still in normal weight range)

ED-NOS behaviours include  

chewing and spitting out food without swallowing , and infrequent bingeing or purging

oral signs of eating disorders

erosion - Restorations may look "raised" as tooth erodes around them

sensitivity

caries

enlarged parotid glands

red injured palate and throat from vomitting

angular chelitis

Russell's sign: calluses on knuckles

Low vit C causes

Bleeding, swollen gums; slow healing (scurvy)

Low B vitamins / iron causes

glossitis, angular cheilitis