^ What he said. IQ is a measurement of capacity for development. So if you are perfectly healthy, have perfect nutrition, perfect exercise, perfect learning, etc. you could perfectly realize your development. This is unlikely to happen, and there are various things (malnutrition, lack of exercise) that can lower your performance IQ temporarily, but you can't really change your capacity for development. And you can't add to it.
You're mistaking IQ with the underlying factors which it is derived from. IQ is, by definition, just a function of your scores on a bunch of standardized tests which try to determine your intelligence. If you can study for the kinds of questions the tests ask you, you can improve your IQ. It is a different story from improving whatever the underlying factors are.
For example, some IQ tests ask you "What's the next number in this series...". If you aren't very good with numbers, you might do very poorly on this section. However, if you sit down and learn about a lot of the patterns that show up frequently in those types of questions, then you may increase your score dramatically on that section, and thus improve your IQ.
