Before you can begin to lose weight you need to know how many calories you need a day and start reducing from there. Otherwise, you can watch your diet all you want, elimate fast food, soda, alcohol and sweets but if you are eating too many calories you still WILL NOT lose weight. There are 3 steps. So here we go and grab a calculator!
Step 1: find your BMR (this means basal metabloic rate which is basically how many calories you need a day for all your organs and body to sustain life)
For Males: BMR = 66 + (13.7 x lean bodyweight in kilograms) + (5x your height in cm) - (6.8 x age)
So for a 30 year old male at 235 lbs with 10% bodyfat, so a lean mass of 212 lbs or 96 kg on a 5'11" frame or 178 cm it comes out to:
BMR = 66 + (13.7 x 96 kg) + (5 x 178 cm) - (6.8 x 30)
BMR= 2067 calories per day
BMR = 655 + (9.6 x lean weight in kg) + (1.7 x height in cm) - (4.7 x age)
So for a 28 year old female with 15% body fat, so a lean weight of 119 lbs or 54 kg on a 5'6" or 165 cm frame it comes out to:
BMR = 655 + (9.6 x 54 kg) + (1.7 x 165 cm) - ( 4.7 x 28)
BMR = 1323
Step 2: we have to find your activity level
For arguments sake and after speaking to several dietitians the best activity factor is 1.3
So for our male example: 2067 x 1.3 = 2687 a day TO MAINTAIN HIS WEIGHT
For the female example : 1323 x 1.3 = 1719 TO MAINTAIN HER WEIGHT
In order to lose 1 pound a week you MUST create a DAILY 500 calorie a day deficit. So for the male his calories need to be at 2187 if he doesnt exercise, or he can subtract 250 on workout days for a total of 2437 BUT he must burn 250 from exercise or there is no 500 calorie a day deficit. This is why I recommend eating LESS on days you workout to compensate for the other calories that you are NOT burning that day since you are not exercising.
The women would need 1219 daily for a loss of one pound weekly if she does not exercise at all. IF she burns 250 calories DAILY from her exercise then she can eat 1469 a day provided she is workouting out.
This is why it is so important to know how much you are eating each day or you are just spinning your wheels. This is also why you need to be active everyday! Hope this helps