• Chew on ice – ice gets to stomach, ice will melt but requires some energy from the body to do so. So using up energy stores to mlet ice – idea is we will be losing calories. Make sense, nothing wrong with argument but with numbers – calories burnt not significant in terms of weight loss • In pharmacies we have shelves on shelves of supplements supposed to melt fat away, block it from being absorbed and so on. • In America we see weight keeps being oiled on and none of these diets are working Video 2 • Obesity is a risk factor for with heart disease, stroke, high blood pressure (hypertension), cancer and very strong link for diabetes. • BMI – scientific way to look at obesity (accepted way to define it). Weight (kg)/height(m^2). o If the number is bigger than 30 à obese (the smaller the number, the less the weight problem. o There are exceptions: possible to have high BMI because you have a lot of muscle (e.g. bodybuilders) • To gage risk associated with excessive weight, take look at both BMI and waist to hip ratio. The greater the waist to hip ratio, the greater the belly size. o In a graph can see where the danger region is. o The greater the BMI, the greater the hip-to waist ratio, the greater the risk § Red category, risk for conditions associated with obesity increase • “The Calorie” – calorie cannot be empty or full. It is a unit of measure of energy o Amount of energy needed to raise the temperature of 1 gram of water by one degree Celsius • Two types of calories o Food calories – really talking about kilocalories. § 1 (food) Calorie = 1000 calories (1 kilocalorie) § Energy needed to raise the temp. of 1kg of water by 1 degree (from about 15 to 16 degrees) o Also units of work . When you carry out any kind of work (lifting arm, lifting weight) you are expending energy and this energy can also be measured in terms of calories. § To lift weight of 213.4kg 2 metres would require 1 kilocalorie of energy. • Calorimeter – used to determine calorie content of food. Put the food inside and burn it in a supply of oxygen and see how much heat is produced. Calorie content of food is just a measure of the amount of potential energy that it has . o To burn orange juice for example, have to let the water evaporate as water has no calories anyway and then left with the dry stuff which you burn. o Early calorimeters – chamber for food, funnel in some oxygen, start burning food and circulating around it had water. As food burned temp. of water would rise. As
you know the amount of water circulating and how much the temp. went up can calculate calorie. • Wilbur Olin Atwater – first determined calorie content of food o Burned food in calorimeter but also measured amount in fecal matter and urine o Not all the food is combusted in the body as in the calorimeter (CO 2 and H 2 O) o Urea comes out in urine, all kinds of food remnants that come out in fecal matter § Atwater collected all of this and burned that in the calorimeter § Subtracting one from the other, determined how much energy was
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- Spring '11