Cooking makes a difference. Cooked foods are more easily metabolized than raw foods, — therefore fewer calories are required in digesting them and more calories are available to the body. For example, - a well done steak provides more available calories than the raw meat. - raw and cooked carrots burned in a calorimeter would produce the same amount of energy. However, when it comes to the body, raw carrots are harder to break down than cooked ones —> more calories are used up to metabolize them —> they provide less calories than cooked ones • 1 cup of orange juice: 108 Cal • 1 square of fudge: 155 Cal • 1 gram of dynamite: 155 Cal - how come? they produce the same amount of energy in a calorimeter, it’s just that in real life, the energy from dynamite is released all at once, whereas energy from fudge is slowly released - calories in fast food chains = energy produced in calorimeter — so really it’s an approximation Metabolism - Metabolism : The energy consumption by biochemical processes (— everything that goes on in our body requires energy) - Basal metabolic rate (BMR) : amount of energy that we would expend over a 24hr period, doing NOTHING = energy body expends just to stay alive - depends • 1500-1700 calories per day • Sedentary lifestyle - Men: 2200 calories - Women: 1800 calories - NOTE: we don't BURN calories, they are just a measure of energy — we burn FOOD - Calories “burned” during the performance of activities are determined by measuring the amount of O 2 inhaled and of CO 2 exhaled —> proportional to the burning of calories • combustion process = food component + O 2 —> CO 2 + H 2 O - Energy released form several types of activities : • Walking 5.6 km/h (3.5 mph): 4 Cal/min • Dancing: 5.5 Cal/min • Bicycling: 8 Cal/min 12 of 66
• Swimming: 11 Cal/min • Running 16 km/h (10 mph): 16.5 Cal/min VIDEO 4 - Humans are biochemically individual: some people have more efficient metabolisms and therefore require fewer calories to keep their body functioning. Metabolic syndrome - It occurs when you have : • More than 100 cm waist • Triglyceride above 1.7 Mmol/L • HDL under 1 Mmol/L • BP over 130/85 • Blood glucose over 6.1 Mmol/L • Genetic causes - people who have it do better on a low carbohydrate diet than people who don’t — low carb diet works for everyone, it’s just more efficient with these people. GENETICS AND WEIGHT CONTROL - Is being overweight genetic too? - It is linked to it but diet is the trigger • Ex: Pima Native Americans (live in Arizona, Southern US // + Mexico) • Those who live in the US are mostly overweight, however those who live in Mexico are not, because they have a different healthier lifestyle (eat more veggies) - CCL: There is a genetic propensity for being overweight, but in order to bring it out, you have to have a poor diet — its generally a combination - Brown fat / white fat distribution in the body is genetically determined - Brown fat : more adept at metabolizing stored and fat and releasing energy than are other fat cells • if you have more brown fat you are more likely to be lean because that fat is more adept at burning up stored fat and carbs • e.g. : obese rodents have less brown fats = less adept at generating energy. They
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- Spring '11