2TEST YOUR KNOWLEDGEExercise helps reduce the risks associated with overweight and obesity even if it doesn’t result in improvements in body composition. True or False?TRUE. Regular physical activity provides protection against the health risks off overweight and obesity. It lowers the risk of death for people who are overweight or obese as well as for those at a normal weight
3TEST YOUR KNOWLEDGEWhich of the following is the most significant risk factor for the most common type of diabetes (type 2 diabetes)?SmokingLow-fiber dietOverweight or obesityInactivityC. All four are risk factors for diabetes, but overweight / obesity is the most significant. It is estimated that 90% of cases of type 2 diabetes could be prevented if people adopted healthy lifestyle behaviors. About 18 million Americans have type 2 diabetes, and more than 6 million of those with diabetes don’t know it.
4TEST YOUR KNOWLEDGEIn woman, excessive exercise and low energy (calorie) intake can cause which of the following?unhealthy reduction in body fat levelsAmenorrhea (absent menstruation)Bone density loss and osteoporosisMuscle wasting and fatigueALL FOUR. Very low levels of body fat, and the behaviors used to achieve them, have serious health consequences for both men and woman.
5BODY COMPOSITION The relative amounts of fat and fat-free mass Fat-free mass: all the body’s non-fat tissues:BoneWaterMuscleConnective tissueOrgan tissuesTeethBody fat:Essential fatNonessential (storage fat)
6Essential fatLipids incorporated to the nerves, brain, heart, lungs, liver and mammary glandsCrucial for the body functioning3-5% body weight in man8 – 12% body weight in woman
7Nonessential fat Extra fat or fat reserves stored in the body Exists primarily in fat cells or adipose tissueLocated below the skin and around major organsThe amount of nonessential fat depends on many factors: gender, age, heredity, metabolism, diet and activity level.
8Overweight and obesity Muscle tissue is denser and heavier than fat, a fit person can easily weight more than the recommended weight on a height/weight table.For the same reason, an unfit person may weight less than the table’s recommended weight.It is important to consider body composition – percent of body fat.Example:2 woman 5 ‘5’’ tall weight 130 poundsOne has 15% of body weight as fatThe other has 34% of weight as fatNone of them is overweight by most standards, but the second woman is over-fat
9Overweight and obesity Overweight: The total body weight above the recommended range for good healthBMI ≥ 25Obesity: A serious degree of overweightBMI ≥ 30
10Prevalence of overweight and obesity among Americans
11Excess body fat and wellness As overweight and obesity increase, so do the problems associated with themRisk of chronic disease and premature deathMetabolic syndrome resistance to the effects of insulin, high blood pressure, high blood glucose levels, abnormal blood fat levels and fat deposits in the abdominal region.Heart diseaseCancerHypertensionImpaired immune functionGall bladder and kidney diseasesSkin problemsSleep and breathing disordersErectile dysfunctionPregnancy complicationsBack painArthritisBone and joint disorders.Diabetes
12Problems associated with overweight and obesity… Body fat distribution and healthExcess fat in the abdominal area increases the risk of several diseasesCauses are unknown but it appears that abdominal fat is more easily mobilized and sent into the bloodstream
13Problems associated with overweight and obesity… Performance of physical activitiesToo much body fat makes physical activity difficultAs a consequence, overfat people don’t exerciseAn become less fit. They don’t have muscular strength, endurance and flexibility.
14Problems associated with overweight and obesity… Emotional wellness and self-imageBeing perceived as fat can cause discrimination from othersCan contribute to psychological problems such as depression, anxiety and low self-esteem.The ideal body presented by the media is an unrealistic goal
15Problems associated with very low levels of body fat Having too little body fat is also dangerousFat is essential for the functioning of the bodyToo little body fat representsLess than 8-12% in womenLess than 3- 5% in menExtreme leanness is linked with reproductive, circulatory and immune system disorders and with premature death.It might also cause amenorrhea in woman and loss of bone mass.
16Assessing body mass index, body composition and body fat distribution Body mass index (BMI)Measure of body weight that is useful for classifying the health risks of body weightBased on the concept that weight should be proportional to heightBMI doesn’t distinguish between fat and muscle.Calculated dividing your body weight (Kg) by the square of your height (m).
17Calculate your BMIDivide body weight in pounds by 2.2 to convert it to kilogramsMultiply height in inches by to convert it to meters.Multiply the result of step 2 by itself to get the square of the height measurement.Divide the result of step 1 by the result of step 3 to de3termine BMI.
18Assessing body mass index, body composition and body fat distribution… National Institute of Health NIH guidelinesConsider body fat distribution and other disease risk factors in addition of BMIUses the measure of the waist circumferenceDisease Risk Relative to Normal Weight and Waist CircumferenceClassificationBMI (Kg/m2)Obesity ClassMen ≤ 40 in. (102 cm)Women ≤ 35 in. (88cm)> 40 in (102 cm)> 35 in (88 cm)UnderweightNormalOverweightObesityExtreme Obesity< 18,518,5 – 29,925,0 – 29,930, 0 – 34,935,0 – 39,9≥ 40,0IIIIII--IncreasedHighVery HighExtremely highVery high
19Assessing body mass index, body composition and body fat distribution… Percent Body FatUnderwater weightingThe individual is submerged and weighted under waterThe percentages of fat and fat-free weight are calculated from body densityConsiders that muscle has a higher density and fat a lower density than water.Overweight people tends to float and weight less under waterLean people tend to sink and weight more under water.
20Percent Body Fat Skinfold Measurements Involves measuring the thickness of skinfolds at several different sites on the body.You can sum up the skinfold values as an indirect measure of body fatness.Measured with a device called caliper
21Percent body fat The Bob Pod Small chamber containing computerized sensorsMeasures body composition by air displacement rather than water displacementDetermines the percentage of fat by calculating how much air is displaced by the person sitting inside the chamber
22Percent body fat Bioelectrical Impedance Analysis (BIA) Works by sending a small electrical current through the body and measuring the body’s resistance to it.Fat-free tissues, where most water is located, are good conductors of electrical currentFat is a bad conductor.The amount of resistance to electrical current is related to the amount of fat-free tissue in the body.
23Percent body fat Advanced Techniques: DEXA Dual-Energy X-Ray AbsorptiometryMeasures the tissue absorption of high- and low-energy X-ray beamsTOBEC Total Body Electrical conductivityEstimates lean body mass by passing a body through a magnetic field.
24Assessing body mass index, body composition and body fat distribution… Waist circumference measurementWaist to hip ratio calculationDivide your waist circumference by your hip circumference
25Setting body composition goals Establish a goalChoose a target value for BMI or percent body fatMake sure your goal is realistic: genetics limits your capacity to change your body composition.If your body composition is close to the recommended range you might want to set a lifestyle goal rather than a specific percent body fat or BMI goal.Set a target range for body weightDon’t stick rigidly to a recommended body weight calculated from any formula, other factors should also be considered