Body Composition and Weight Control

Geraldine NG, Dietitian,Dietetics Department, Queen Elizabeth Hospital

Body Composition

Assessment of Body Size

Body Mass IndexWaist Circumference Waist-to-Hip Ratio

Assessment of Body Size -BMI

Body Mass Index (BMI) = Weight (kg)Height (m)²

Provides an acceptable approximation of total body fat (BF) in most people.Demonstrates a strong +ve correlation with morbidity and mortality.Provides a direct indication of health status and disease risk.

BMI ClassificationsClassification BMI(kg/m²) Health RiskUnderweight < 18.5 Risk of nutritional

deficiency diseases and osteoporosis

Normal Range 18.5 – 22.9 Low Risk (healthy range)

Overweight 23.0 – 24.9 Moderate Risk

Obese ≧ 25.0 High RiskSource: Asian Academy For Sport & Fitness Professionals; WHO 2001

Limitations of BMIProvides no information about regional Body Fat distribution.Is only moderately correlated with % BF –overestimate individuals who are very muscular and underestimate those who have lost muscle mass.

Muscle is heavier by

volume than fat !

Waist CircumferenceFat distribution – an important marker of disease risk.Deep abdominal (visceral) fat is a strong independent predictor of disease.

ObesityApple Shape –Central Obesity

At higher risk for health complications:•Hypertension•Hypercholesterolemia•Diabetes•Cardiovascular disease•Metabolic syndrome•Gallbladder diseaseWomen• Oligomenorrhoea• Breast cancer

Pear Shape

At lower risk for health complications

Recommended Waist Circumference

Female Male

< 31.5 inches(80cm)

< 35 inches(90cm)

Waist-to-Hip ratioFurther confirms the obesity problem

↑Ratio reflects android obesity

Measurement of WC is preferred when assessing risk of disease as WC provides a better measure of deep abdominal fat than W-to-H ratio.

Waist-to-Hip ratio = Waist Circumference (cm/inch)

Hip Circumference (cm/inch)

Classification W-to-H ratioWomen Men

High Risk >0.85 >1.0Moderate Risk 0.80-0.85 0.90-1.0Lower Risk <0.80 <0.90

Source: Asian Academy For Sport & Fitness Professionals

Body FatBioelectrical Impedance Analysis

Commonly used in field settings.Works by sending a low, safe electrical current through the body; the resistance of the fat tissue to the current is then measured.For better comparison of results, always use the same scales in the same conditions. (preferably rested, not dehydrated, and have been to the bathroom)

Track long-term changes

Body Fat % ChartWomen Men

Essential Fat 10 - 12% 2 - 4%Competitive Athletes 14 - 20% 6 - 13%General Health 21 - 24% 14 - 17%Acceptable 25 - 31% 18 - 24%Obese ≧ 32% ≧ 25%

Source: Asian Academy For Sport & Fitness Professionals

Weight Control

Energy Balance

ENERGY IN (calories consumed) = ENERGY OUT (calories burned) over time

weight stays the same

More IN than OUT over time wt gainMore OUT than IN over time wt loss

Counting Calories

1lb Fat your body stores = 3500 calories of unused energy

To lose 1lb, need to create a calorie deficit of 3500kcal by:

Taking in 3500 less kcal over a period of time than you needDoing 3500 kcal worth of exercisePracticing both simultaneously

Recommendation: lose no more than 2 lbs/wk for lasting weight loss.

Estimated Energy Requirements (EERs)

Total daily energy expenditure (TDEE)60-70%: Resting energy expenditure (REE) 5-10%: Dietary-induced thermogenesis/ thermal effect of food25-35%: Thermal effect of exercise – physical activity

Energy expenditure can be measured by a portable indirect calorimeter.

Can also be estimated by prediction equations.

RMR Prediction EquationsEquation Males FemalesSchofield with height* 15.057W-0.1H+705.8 13.623W+2.83H+98.2

Harris-Benedict* 66.47+13.75W+5H-6.76A 655.1+9.56W+1.85H-4.68A

Mifflin* 5+10W+6.25H-5A -161+10W+6.25H-5A

Rule of Thumb Sedentary: 30kcal/kg; lightly active: 35kcal/kg; moderate active: 40kcal/kg

A, age in years; H, height in cm; W, weight in kg.* These equations estimate only resting requirements. Activity factors may need to be considered for energy expended in activity.

Example:June, female, age: 25, ht: 163cm, wt: 50kg, Sedentary

Schofield with ht: 13.623(50)+2.83(163)+98.2 = 1241kcal

Harris-Benedict: 655.1+9.56(50)+1.85(163)-4.68(25) = 1318kcal

Mifflin: -161+10(50)+6.25H-5(25) = 1233kcal

Rule of Thumb: 30kcal/kg x 50kg = 1500kcal

Dietary Recommendations

A balanced diet should be part of any weight control plan.

A diet high in complex CHO and moderate in protein & fat will complement an exercise program.

Daily intake should not be <1200kcal unless under a dietitian/ doctor’s supervision.

Dieting?

Crash/ Fad dietsSome involves severely restricted kcal intake, similar to starvation

Some involves consumption of only one type of food or a small amount of at least one food group

Exercise not emphasized

May result in noticeable wt loss in a short time but much of this loss is water

Lose muscle instead of fat

Wt regains quickly as pre-crash diet is resumed

“There are no "superfoods." That's why you should eat moderate amounts from all food groups, not large amounts of a few special foods.” The American Heart Association.

Popular Crash/Fad DietsAtkins Diet: Low carbs, High protein. Starting with only ≤ net

20g CHO/dZone Diet: 40: 30: 30 ratio of kcal obtained daily from CHO,

Protein, fat. (vs. HE ~55:15:30)Example: 1500 kcal diet

40%CHO 150g; 30%PTN 113g; 30%FAT 50gvs

55%CHO 206g; 15%PTN 56g; 30%FAT 50g

Cabbage Soup Diet: Heavy consumption of a low-kcal cabbage soup for 7 days. Often <800kcal/day

Master cleanse (lemonade) Diet: Consume 6-12 glasses of a drink made from fresh lemons, maple syrup and cayenne pepper. No solid food provides 600-1200kcal/day

Grapefruit Diet: Low carb. Half a grapefruit or juice with each meal and reduce kcal intake often to <800kcal/day

Estimating the cost of Physical Activity“ How much do I have to exercise to

burn the calories of a piece of cake?”An estimation of energy expenditure can be made using metabolic equivalents (METs)METs estimate the metabolic cost (or oxygen used) during PA. 1 MET is the caloric consumption of a person while at complete rest

3.5ml O2/kg/min or 1 kcal/kg/hr = 1 METMET levels ↑with the intensity of an activity

Understanding and Using METS

You will need:Body weightMET valueTime spent on the activity

Example: 60kg female ironing her shirts for 45 minutesBW: 60kg, MET: 2.3, Duration: 0.75hrPlug them in! = 2.3 x 60 x 0.75 = 104kcal

Met value of activity x body wt (kg) x time (hr)

Individuals with greater BW will burn more calories/sec !

=1 piece spring roll

Compendium of Physical Activities

METS Specific Activity Examples1.0 Inactivity, quiet Lying quietly and watching television

2.5 Music playing Piano or organ

8.0 Running Running, 5mph (12min/mile)10.0 Bicycling Bicycling, 14-15.9mph, fast, vigorous effort15.0 Running Running, stairs, up16.0 Running Running, 10mph (6min/mile)

3.0 Occupation Standing; light/moderate, patient care (as in nursing)

2.5 Conditioning exercise Mild stretching

3.5 Home activities Vacuuming4.0 Sports Tai Chi4.0 Bicycling Bicycling, <10mph, leisure, for pleasure

2.5 Home activities Cooking or food preparation – walking

3.0 Walking Walking the dog

Source: Ainsworth, B.E., Haskell, W., Whitt, M.C., Irwin, A.M., Strath, S.J., O’Brien, W.L.,…Leon, A.S. Compendium of physical activates: an update of activity codes and MET intensities. Med. Sci. Sport Exerc., Vol.32, No.0, Suppl., pp. S498-S516, 2000

Some fun factsPhysical activities that can consume about 150kcal

15 min Stair Climbing 1.5 tbsp Butter

15 min Rope Skipping 1 piece deep-fried meat dumpling

20 min Swimming (freestyle) 1 scoop Soft ice-cream

30 min Aerobic/ Social dance 1 piece deep-fried taro dumpling

30 min Cycling(5 miles accomplished) 0.5 Cream Bun

15 min Running on level ground(1.5 miles accomplished)

45 min Volleyball 3 pieces Nougat

30 min Walking(2 miles accomplished) 0.5 cup Red bean icy drink

35 min Strolling (1¾ miles accomplished) 1 can Cola

Source: Leisure and Cultural Services Department

Benefits of Physical Activity in a Weight Control ProgramBesides burning excess Body Fat, it also:

Builds muscle tissue and muscle uses kcal up at a faster rate than BF.Helps reduce inches and a firm, lean body looks slimmer even if your wt remains the same.

Metabolic rate stays elevated for some time after vigorous exercise use more kcal in the resting stage.

Exercise also…↓the risk of developing CVD, DM, High BP, cancers↓ feelings of anxiety and depressionpromotes psychological well being and self-efficacyhelps build strong bones and joints

Common QuestionsShould I take protein powder?

Protein requirements for adultSedentary: 0.8g/kg/dEndurance: 1.2-1.4g/kg/dStrength: 1.6-1.7g/kg/d

Can be expensive and high in kcalShould be able to meet requirements easily by eating natural sources only

What is Carbohydrate loading? Do I need it?A strategy used by endurance athletes to maximize the pre-exercise muscle glycogen stores ↑exercise time to exhaustion(>90mins)Contains a high-carb dietary regimen that lasts a few days before competition.

Common Questions – cont’d

Do you recommend sport drinks?

May consider it if exercise>1hr durationBenefits of sports drinks:

• Improves palatability• Provides a source of fuel for

active muscles• Stimulates fluid absorption from

the intestine

Sport Drinks CHO (%) Na (mg)Gatorade 6.0 405

Pocari Sweat 6.6 483Watsons Iso Tone Pure-Ice

6.5 474

BonaqueBonActive

4.2 237

Lucozade Sport 6.4 495

Thank you…