Energy requirements of the body. A 70 kg human uses energy at the rate of 80 J/s, on average, for just resting and sleeping. When the person is engaged in more strenuous activities, the rate can be much higher. (a) If the individual did nothing but rest, how many food calories per day would she or he have to eat to make up for those used up? (b) In what forms is energy used when a person is resting or sleeping? In other words, what happens to those 80 J/s? (Hint: What kinds of energy, mechanical and otherwise, do our body components have?) (c) If an average person rested and did other low-level activity for 16 hours (which consumes 80 J/s) and did light activity on the job for 8 hours (which consumes 200 J/s), how many calories would she or he have to consume per day to make up for the energy used up?
Energy requirements of the body. A 70 kg human uses energy at the rate of 80 J/s, on average, for just resting and sleeping. When the person is engaged in more strenuous activities, the rate can be much higher. (a) If the individual did nothing but rest, how many food calories per day would she or he have to eat to make up for those used up? (b) In what forms is energy used when a person is resting or sleeping? In other words, what happens to those 80 J/s? (Hint: What kinds of energy, mechanical and otherwise, do our body components have?) (c) If an average person rested and did other low-level activity for 16 hours (which consumes 80 J/s) and did light activity on the job for 8 hours (which consumes 200 J/s), how many calories would she or he have to consume per day to make up for the energy used up?
Energy requirements of the body. A 70 kg human uses energy at the rate of 80 J/s, on average, for just resting and sleeping. When the person is engaged in more strenuous activities, the rate can be much higher. (a) If the individual did nothing but rest, how many food calories per day would she or he have to eat to make up for those used up? (b) In what forms is energy used when a person is resting or sleeping? In other words, what happens to those 80 J/s? (Hint: What kinds of energy, mechanical and otherwise, do our body components have?) (c) If an average person rested and did other low-level activity for 16 hours (which consumes 80 J/s) and did light activity on the job for 8 hours (which consumes 200 J/s), how many calories would she or he have to consume per day to make up for the energy used up?
Judy has started fast walking for half an hour each day in an effort to lose weight. Judy currently weighs 100kg. She walks expending about 0.1 kcal per kg of body weight per minute. For a woman, we multiply the body weight in kg by 0.9 kcal/kg body weight/hour to calculate her BMR. What is Judy’s daily energy expenditure? (Ignore TEF due to its small portion).
Under normal conditions the human heart converts about 12.5J of chemical energy per second into 1.25 W of mechanical power as it pumps blood throughout the body.
HINT
(a) Determine the number of Calories required to power the heart for one day, given that 1 Calorie equals 4186 J.
Cal
(b) Metabolizing 1 kg of fat can release about 9000 Calories of energy. What mass of metabolized fat (in kg) would power the heart for one day?
kg
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Your brain consumes about 22 W of power, and avocados have
been shown to promote brain health. If each avocado contains 310 C, and your
brain were powered entirely by the energy from the avocados, how many must
you eat each day?
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