It is a quite simple equation that in order to lose body weight, which is almost exactly another way of saying in order to lose body fat, we have to reduce our intake of calories. We just need to have a rough idea of how many calories you consume in an average day and then begin to tilt that balance in our favor.
It is critically important that you go slowly into this process. When most people attempt extreme changes in their eating patterns they find that the body reacts in a very mystifying way by actually reducing the number of calories that it needs in order to function properly day by day. If your body then kicks into what we call starvation mode, even though you are eating less you are not losing any weight. This starvation mode is usually the culprit.
The common view of losing weight is that we must immediately drop our average daily calorie consumption to 1000 calories per day or less. This is insane. Your body simply will not tolerate this without rebelling by slowing down your metabolism so that it actually needs fewer calories to function efficiently. You will also find it extremely difficult to stick with extreme changes in your eating patterns.
Body fat loss is accomplished by taking things slow and steady. During the first week in order to not have your body go in to the starvation response, it does not matter how many calories you have been consuming up to this point only reduce that approximate total by 10%. Depending on how committed you are to making this work you might even consider tracking your calorie intake for one to two weeks to get a reasonable approximation of how many calories you normally eat in an average day.
By making many smaller reductions in your daily calorie intake week by week you lessen the danger dramatically of your body defending against losing weight. You're also more likely to be able to stick to your goals if you are only reducing your daily calorie intake by a small amount.
In the same spirit you might want to avoid making any kind of dramatic increase in the amount of exercise that you get during that first week as well as subsequent weeks. Once again, in order to not be betrayed by your body, it is important that whatever your normal amount of exercise is during a given week that you only increase it by small amounts. Once again this works with your body and your mind.
Having gone successfully through your first week with an approximate 10% reduction in the calories consumed and maybe, just maybe, a small increase in your normal exercise routine once again you reduce your calorie intake for the second week by 10%. What you are doing is manipulating your body's metabolism so that it works with you instead of against you. Continuing with this program week after week will give you a realistic and real life decreases in the amount of body fat that you carry.