Weight Loss is a Numbers Game
Well, here is the good thing about weight loss and nutrition - at its core, it's very simple in premise - you need to burn more calories per day than you take it. You need to have a calorie deficit in order to lose weight. Sounds easy right? Well, obviously easier said than done.
For every pound of fat you want to lose, you need to burn about 3,500 calories. That means that in a given week, everyday you need to expend 500 calories more each day than you take in. So where do you start?
The first thing you need to do is to calculate your BMR or basal metabolic rate. This is the number of calories you burn by just existing. To extrapolate on this, you need to know and take into account your activity level. A person who sits on the couch the entire day and does nothing has a very low total daily energy expenditure (TDEE), whereas a person who is very active will have a high TDEE. TDEE is known as your maintenance calories- meaning if you take in that amount of calories everyday you will maintain your same weight.
Now here's the good news - you don't need to do a lick of math yourself. Just Google BMR calculator and TDEE calculator and there are numerous programs that will cook up your results in mere seconds. Once you know your TDEE, you just need to build a deficit from this.
When I started losing weight, I weighed 275 pounds and was lightly active. To maintain my current weight, I would have to have consumed roughly 2,800 calories per day. Now since I was gaining, it is obvious that I was routinely going over that calorie allotment. I have now been eating anywhere from 1,500-1,800 calories per day, hence losing about 2 pounds per week with a calorie deficit of 1,000-1,300 calories per day.
The more you exercise, the bigger your calorie deficit and the more weight you will lose. Doing the initial calculations for this will really help you put into focus exactly what you need to do in terms of daily caloric intake.