How to Lose Weight - The Basics

Calories per Pound

The first step on how to lose weight is knowing how many calories you must burn in order to lose 1 pound of fat. 
One pound of body fat contains approximately 3500 calories.
Simply put, this means that you must burn 3500 calories more than what you already burn during your daily activities in order to lose one pound of body fat.

Weight Loss Equation

The best way to lose weight will be through a combination of controlling what you eat and adding some exercise to your weekly schedule.
The first step you should take is to figure out how much weight you want to lose and over what period of time you want to lose that weight.
For example, if you wanted to lose 2 pounds of fat per week then you would need to lose a total of 7000 calories (3500 per pound of fat x 2 pounds). Then take that 7000 calorie total and divide it by 7 days and we find out that we need to create a 1000 calorie deficit per day in order to lose 2 pounds of fat in 1 week.

Exercise for Weight Loss

Now if we tried to create this 1000 calorie deficit by only using exercise, we would need to run for about 1.5 hours every day of the week. Likewise, if we tried to create this deficit purely off the diet, we would need to cut out about 3 bowls of cereal worth of food per day.
Neither of these options will fit into most peoples lifestyles, so we will use a combination of diet and exercise to accomplish our goals.
If we split the calorie deficit into two equal parts we would need to create a 500 calorie deficit from exercise and a 500 calorie deficit from dieting.
This would be the same as cutting out 2 bottles of coke or eating a homemade a sandwich instead of a fast-food burrito for our diet part of the calorie deficit and adding about 45 minutes of exercise every day.

Lose Weight Without Exercising

If you don't have much time for exercise it is also possible to lose weight strictly by watching what you eat.
This is especially true if you eat a lot of fast food, which has very high-calorie content in them.
A small to medium-sized fast-food burrito will typically have 475 to 800 calories, while a large fast-food burrito may have 1000+ calories in just one burrito! If you switch out a medium-sized fast-food burrito for a homemade sandwich of about 300 calories (bread, meat, lettuce, tomattoes, no mayo) you essentially "burned" 175 to 500 calories just by not eating fast food for lunch!

Calculating BMR

On a daily basis, your body consumes calories to keep you alive. The measure of how many calories your body uses every day just to keep you alive is called your Basal Metabolic Rate (BMR).
For a male, their BMR is usually between 2300 and 3800 calories burned per day, and this number varies greatly upon how active of a lifestyle you have.
Female's BMR is usually between 1600 to 2700 calories per day, once again this number varies upon how active of a lifestyle you have.
Using the BMR Calculator you can find out how many calories your body burns every day just to stay alive.
Knowing your BMR is very useful if you plan to lose most of your weight by dieting with only very little or no exercise.

BMR and Calorie Deficit

After using the BMR calculator to calculate your BMR, add up the total amount of calories you consume per day. Now take your BMR calories minus your calories consumed and you get the number of calories left over.
For example, if your BMR is 2000 and you only eat 1400 calories per day, then you already have a 600 calorie deficit per day!
Take 600 calories per day and multiply that by 7 days (600 x 7) and you find out that you will burn an extra 4200 calories per week.
Take 4200 calories per week, divide it by 3500 calories per pound and you find out that just by dieting alone you can lose 1.2 pounds per week.

Using the Only Diet for Weight Loss

Taking this idea of losing 2 pounds per week by dieting alone to the extreme, you could eat 3 homemade sandwichs a day (3 x 300 calories), which is only 900 calories of food consumption per day.
Now if your BMR is 2000 and you subtract 900 we have an 1100 calorie deficit per day.
Take that 1100 calorie deficit per day and multiply it by 7 days, which comes out to an extra 7700 calories per week.
Take 7700 calories per week and divide it by 3500 calories per pound and we find out that by only using a very strict diet you could lose 2.2 pounds per week!