Question

1. Trying to stay awake to study, a second year medical student added three 12-oz cans of caffeinated soda a day (~40 g sugar/can) to her diet. She did not otherwise change her diet or physical activity. How much weight would she be expected to gain the next 6 months?

2. After 6 months, the student as described in the first question now wants to lose the weight she gained. She decided to walk 3 miles five times per week. She looks up exercise physiology studies and determines that she will burn about 75 kcal/mile walked. How long will it take to lose the added weight?

**Please answer this question from a biochemical perspective and explain the reason why**

Answer 1

1. Grams of sugar in one can of caffeinated soda = 40 g

Number of cans consumed per day = 3

So, number of cans consumed in six months = 3 $\times$ (30 X 6) = 540

So, total grams of sugar consumed in six months = 540 X 40 = 21,600 g

Since she has not changed her diet or physical activity, all the consumed sugars will add on to the weight of her body. Hence, total weight gain in the next 6 months is expected to be 21,600 grams or 21.6 kilograms.

2. Calories in one gram of sugar = 4 cal

Total weight gain of her body = 21,600 g

So, total calories gained by her body = 21,600 X 4 = 86,400 cal

Calories burned per mile walked = 75 cal

So, total miles to be walked to burn all calories gained = 86,400 $\div$ 75 = 1,152 miles

Miles walked per time = 3 miles

Number of times walked per week = 3 X 5 = 15 miles

So, number of weeks to be walked = 1,152 $\div$ 15 = 76.8 weeks = 19.2 months = 1.6 years

Hence, it will take her a total of 1.6 years to lose the weight she gained.