It is important to understand that weight is entirely a function of input and output. The input is the food you eat and the calories contained therein. The output is your energy output. To lose weight the output needs to be greater than the input. It is that simple. Do not believe any of the diet fads. If you are currently not gaining or losing weight then just burning 300 extra calories per week or eating/drinking 300 calories less per week (2 sodas for example or a small burger) WILL make you lose weight - in this case around 5 pounds of fat per year.
If you want to lose weight, avoid special “low-carb” products that are full of carbs. This should be obvious, but creative marketers are doing all they can to fool you (and get your money). They will tell you that you can eat cookies, pasta, ice cream, bread and plenty of chocolate on a low-carb diet, as long as you buy their brand. They’re often full of carbohydrates. Don’t be fooled.
It may seem obvious to set realistic weight-loss goals. But do you really know what's realistic? Over the long term, it's best to aim for losing 1 to 2 pounds (0.5 to 1 kilogram) a week. Generally to lose 1 to 2 pounds a week, you need to burn 500 to 1,000 calories more than you consume each day, through a lower calorie diet and regular physical activity.