According to one of my textbooks, 1g of fat contains roughly 9.4kcal. That means that 1kg of fat (2.2lb) is 9,400kcal. That means that 4.5kg (10lb) of fat is roughly 42,300kcal.
Now, the average adult (according to the statistics on the side of my cereal boxes, which I assume are inaccurate) consumes 2,400kcal/day, which is 16,800kcal in a week.
Mass is condenced energy, and calories are a measure of heat (which allows us to measure energy), so to lose 10lb of fat your body has to expend 42,300kcal more than it's given. 16,800-42,300kcal=-25,5 00/week, or -3,643kcal/day. Obviously, you can't consume a negative amount of calories, so even if you consumed 0kcal/day (which I strongly recommend against), you'd still have to increase your activity by 3,643kcal worth each day. If you actually eat (which I do recommend), it would be more than that.
The average person, according to nutrition and body composition expert Lyle McDonald (not to be confused with Ronald), can consistently burn about 5-10kcal/min of moderate intensity activity, which yields 300-600kcal/hour. You're looking at just over 3,600kcal, so we're talking 6-12 hours of exercise per day. That's before we do anything to neutralise the amount of food going into your mouth. If you consume 2,400kcal/day, then that's another 2,400kcal that needs burning, so we're talking an extra 4-8 hours of exercise. All up, that's 10-20 hours of exercise per day, for a week. Sound doable?
Now, can you make the scale drop by 10lb in a week? Yes. Will you have lost 10lb of fat? Extremely doubtful.
- Response by ryanthegreatarj
, An Intellectual Guy, Male, 26-28, Student