Answer to Question #265813 in General Chemistry for DOY

Question

Suppose that when you run through a 50-meter distance you perform 2kJ of work. If before running, you eat food from which you obtain 800 J, would this activity cause you to slim down or to increase your weight? Explain.

Answer 1

Our bodies convert chemical energy stored in food into work, thermal energy and/or stored as chemical energy in fatty tissues.

Work done include accelerating to a full run because they are accompanied by exerting forces on the outside world.

If a person needs more energy than they consume, the body must draw upon the chemical energy stored in fat.

If one eats food that provide $800g$ and the activity is of $2000J$

Energy deficiency $= 2000-800$

$=1200J$

Assuming energy content of fat $= 39000J/g$

The amount of fat loss

$=\frac{1200}{39000}=0.031g$

The change in fat reserve is negligibly small

The amount of exercise needed to produce a noticeable loss in fat can be large

However, using more energy in exercise than one consume can progressively make somebody to slim.

Exercises can be helpful in losing fat.