Weight loss is 70% nutrition, 20% exercise, 10% planning and education. I'm going to start this part with the education.
I was going to the gym from my second year of uni (after I'd put on the fresher 5kg)... and I'd go, workout on the bike and cross trainer, see that I'd burned 600cal and say YAY! I get to eat more tonight!
Losing weight is a math game. You have to know your numbers. You have to know the numbers that are going in and coming out of your body. To lose weight, you must have more calories being burned by your body than coming in. The general rule of thumb is 500cal less than your AMR (Active Metabolic Rate). You will then lose 1lb in a week.
I tend to work off of my BMR (Basal Metabolic Rate). This is the number of calories your body would burn if you were in a coma and your hair and skin are growing, your heart is beating, and your lungs are breathing. You can calculate yours here. Mine is 1570 at a height of 5'9" and 160lb, age 22.
Now, to figure out your AMR, you times this number by how active you are on a daily level... as follows:
1.1 - Office worker, sit at a desk all day and don't move a lot
1.2 - Teacher, on feet a lot, walking around
1.3 - Gym instructor, moderate activity for most of the day
1.4 - Heavy activity most of the day, construction worker etc.
If you're between two of these, times by 1.15, 1.25 etc, as I am - I'm an Executive Assistant, an office job, but I have to rush around a lot. So my AMR is 1805 calories per day.
So I could easily eat 1600-1800 cal per day and maintain my weight, which I have done from June last year up until the beginning of this month (then I started losing again!). If you wanted to lose weight from nutrion alone, you would have to eat 500 less than this number to lose 1lb per week (1300 cal). Now I like my food, so I'm not going to be able to survive on 1300cal a day. I make my limit 1500-1600 cal per day. I supplement this with exercise.
When I go to the gym, I aim to burn 500-600cal, I easily do this by doing high intensity classes (Les Mills BodyAttack, and BodyPump are my favourite!) but I also supplement my days out of the gym with long walks, jogs, or BodyBalance.
So, if I'm eating 1500cal in a day, but I'm burning 1800cal in a regular day - and my exercise burns an additional 500cal, I am in deficit of 800cal that day, not that I exercise every day (4 times a week) but in a week, if I burn 800cal for four days (3200 cal) and only 200 the other 3 days (600cal) then I have still lost an entire pound of fat (3800cal). 1lb of fat = 3500cal.
Of course, there are exclusions - if you have to much salt, you will weigh more due to sodium retaining 50 times its weight in water, so when you eat more than 1500mg of sodium in a day, you can see the scale rise up to 2kg or 5lb overnight.
Make the first baby step of figuring out how many calories are in your meals. Use a meal planner like MyFitnessPal or CalorieCount. Logging your meals and exercise are a great motivator. also, taking before pictures, measurements and weight and seeing the numbers drop monthly are a great motivation to keep going. I remember passing the 5kg mark (Yay! New Jeans!), 9kg mark (into a healthy BMI!) and the 10kg mark (OMG 10kg! That's like a sack of potatoes!), and hopefully beyond.
Stay tuned for parts 2 and 3...