I have been doing some scientific research lately and have discovered some ground breaking correlations. I hope to submit them to scientific journals and having them published in the near future. Your Fitness Quest is excited to share these findings with you.
I have discovered that weight gain is directly related to the amount of stuff you put in your mouth. The probability of weight gain is further increased when you chew and swallow the stuff. Most people eventually relinquish the stuff they ingest a day or so later but by that time it has given off most of it's beneficial properties including the ones that make you gain weight and is not as valuable or desirable.
Conclusion: if you are trying to lose weight, don't put so much stuff in your mouth.
Sorry for being a smart alec, but I think sometimes we make things more complicated then they need to be. If you are overweight and want to do something about it, then it is important to create an energy deficit (eat less than your body burns each day). If you are taking in more calories than your body needs, the first law of thermodynamics states that excess energy (food) will be stored in the form of fat.
Many people, including myself, eat more than they should. If you are not happy with the results you are getting, then stop kidding yourself by just estimating how much you eat and start using a food journal. It might be a pain in the neck for a while, but it is extremely helpful and will be an educational experience. It will help you learn more about food and yourself. There are tons of free websites and smart phone applications that can help you track your calories and in turn identify the pitfalls to your eating. If you haven't tracked your food intake before, I encourage you to do so for a week. It can be a very insightful experience.