You can do it - it is possible to lose 100lbs in 30 days. You will work your tail off and live on a very restrictive diet.
This is a very tough diet and requires a high level of discipline. Just focus one getting through each day for the next 30 days and you will be amazed to see what the human body is capable of achieving.
Your daily diet should consist of protein only, beef, chicken, lamb, pork, and lots of spinach or leafy greens. Avoid fish, shellfish, all non green vegetables and all fruit.
The size of each meal should not exceed what you can hold in the palm of your hand. Plan to eat 8 meals throughout the day and drink water only during the 30 day period.
Each day do 30 minutes of cardio at your own pace and comfort level, the goal is to break a sweat in the first 5 minutes and maintain a good sweat for the remaining work out to bump up your metabolism. Don't work yourself into exhaustion.
OK a challenge...lose 100 pounds in 1 month....let's see how this can be done:
First of all, the more you weigh, the easier it will be to lose a lot of weight in the first few weeks. So lets assume you are 300 pounds.
Now lets calculate your maintenance calories, the calories your body needs to maintain it's current weight:
bodyweight x 15... So 300 x 15 = 4,500 calories/day.
Now, the lowest you should go in calories each day as a woman is 1,200 calories. You could try this as a guy(if you are male) but most guys require at least 1,500...
So, anyways, this would put you at a daily deficit of 4,500 - 1,200 = 3,300, which is ALMOST 1 pound lost each day (1 pound = 3,500 calories burned).
Now, if all you did was just eat 1,200 calories, in 1 month, you would burn 99,000 calories which is 28 pounds.
Now chances are you wouldn't lose those 28 pounds exactly because as you get lower in weight, your maintenance calories goes down, but for simplicity sake, lets say you lost 28 pounds.
Now, that means that you'd still need to lose 71 pounds.
Chances are a few of those 71 pounds are going to come off the first week as water weight, so lets just say we need to lose another 65 pounds.
1 hour of cardio would burn 500 calories, and it would take 7 hours to burn 1 pound...so 7 hours x 65 = 455 hours.... This is an average of 18.9 hours/day for 30 days.
So basically all your waking hours would need to be spent doing cardio.
Now I hope this sheds light for those who read this of just how unrealistic goals like this are.
The human body can only do so much and it is not healthy to push yourself to extremes, it's much better to set new healthy habits and lose weight at a rate which doesn't starve yourself our require you to spend hours a day at the gym.
You can't do that. But if you work out (especially cardio) and you have a healthy diet then you can lose weight very easy.
It would be better if you allow yourself at least 6 to 12 months to lose 100 pounds.
The rule of thumb is 1-1/2 to 2 pounds per week. This is also the safest way to lose weight.