it depends on the person.
It takes 3,500 calories to equal one pound of body weight.
so you would have to lose approximately 3000 calories a day,,,
but you'd have to also factor in what you are eating.
losing 3000 calories a day, eating almost nothing IS VERY DANGEROUS.
losing 20 pounds in a month is probably not safe.
try 20 pounds in a year.
also, i recommend you just ride as far as you can, using the smallest gear [ the gear which is the hardest to pedal]
it helps if you can find a track or circuit to ride, so you don't end up tired 20 miles away from your house. then you can take a rest and pedal home slowly on the biggest gear.
remember, don't push yourself past the limit. if after exercising you feel dizzy, do not exercise that hard. it could also be a sign that you did not eat enough or drink enough.
about 3 pounds
6 pounds in a week
Each person varies with how long it will take to lose 30 pounds. On average, a person can lose around 2 pounds per week. It would take 3.75 weeks to lose 30 pounds with diet and exercise.
Two pounds
if you lost 4 pounds each week and you wanted to lose 40 than you would have to do that for 10 weeks.
Three days
There is no way to lose 23 pounds every week consistently. This is very unhealthy and not advised by any doctor.
How long it normally takes to lose 50 pounds can vary greatly from person to person. As a general rule, losing one to two pounds per week is a safe goal. If you lose two pounds per week it will take a little over six months to lose 50 pounds.
you will lose about 5 pounds. Because for every 3400 calories you burn it is a pound, so take 17500 and divide it by 3400
Yes, you can easily lose three pounds by starving. However, there are much easier ways to lose three pounds. Try cardio exercise every other day and you will soon burn off those three pounds.
By excising more everyday.
Depends on how hard you go at it, but I'd guess somewhere in the 1200-2000 calorie range.