really understand what’s going on is to look at the science behind weight control.Video 2 Notes Obesity:Linked to heart disease, stroke, high BP (hypertension), cancer and diabetes
BMI:The accepted way of defining obesityWeight (kg)/ Height (m2) > 30 = OBESE. Smaller the number, better it isException: possible to have a high BMI, if you have a lot of muscle.Way to gauge the risk of this is to look at BMI and waist/hip ratioGreater the waist to hip ratio = greater the belly sizeWhen you fall into red category of the chart, risk is increased for diabetes, cancer, etc.Key to understanding what happens in weight loss and gain is to understand THE CALORIESCalorie:A calorie cannot be empty or full. 2 types:It is a unit of measure of energyCalories are also units of workDefine: amount of energy needed to raise the temperature of 1 gram of water by one degree CelsiusCaloric amount is amount of energy released when food is burnedFood calories = kilo calories1 calorie = 1000 calorie (1 kilo calorie)Determining the calorie count of food using a calorimeterPut food in there and burn it in a supply of oxygen and see how much heat is produced. Calorie content is just how much energy it has. CalorimeterEarly calorimeters: just had a chamber where you burned food and you funnelled in oxygen, around which you would have water circulating (temp would rise as food burned)As temp rises, you could calculate the calories produced Today: more sophisticated The original calorie content of food done by Wilbur Olin Atwater about 100 years ago Burned food in calorimeterAlso measured what came out in fecal matter and urine
Calories are not handled same way in body and calorimeter body does not combust all of it to H2O and CO2Urea:Comes out in urine and other food remnants come out in fecal matterAtWater collected and burned urea in a calorimeterSubtracting one from another how much calories from each foodDiscovered the classic numbersoFat = 9caloProtein = 4 caloCarbs = 4 caloFibre = 2 cal Fate of food in body IS NOT THE SAME AS IN A CALORIMETER.Texture makes a differenceWhite and whole grain bread, in calorimeter, get the same amount of calories, but in body, they are not handled the same way Components of food are not digested same way more or less energy may be needed depending on fibre contentWhat we are really interested in is the METABOLISABLE ENERGY: how much energy is really available to us in foodVideo 3 - Metabolizable Energy:Burn food in calorimeter, you might produce 400 calories does not mean that 400 calories are available to the body because some of the food components are broken down and body has to use energy to break it downCooked foods more easily metabolized, because you have already pre-digested them through the cooking process Ex: have to expend more calories to digest raw carrots than cooked carrots.
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