Half of this comment is wrong:
It's not a matter of "simply" taking in fewer calories. Your body has a weight setpoint that it likes to maintain, and if you just decrease your caloric intake while eating the same type of food at the same intervals, your body will start burning less. "So just eat less, count calories and weight the food using kitchen scales." is equally wrong in the same way.
There have been scientific studies done on this (from "The Obesity Code", which is a good book backed up by a lot of empirical evidence (some notes are at http://www.criticalthink.info/webindex/BkObesityCodeFung.htm)):
> Thirty-six young, healthy, normal men were selected with an average height of five foot ten inches (1.78 meters) and an average weight of 153 pounds (69.3 kilograms). For the first three months, subjects received a standard diet of 3200 calories per day. Over the next six months of semi-starvation, only 1570 calories were given to them. However, caloric intake was continually adjusted to reach a target total weight loss of 24 percent (compared to baseline), averaging 2.5 pounds (1.1 kilograms) per week. Some men eventually received less than 1000 calories per day. The foods given were high in carbohydrates, similar to those available in war-torn Europe at the time--potatoes, turnips, bread and macaroni. Meat and dairy products were rarely given. In addition, they walked 22 miles per week as exercise. Following this caloric reduction plan, their calories were gradually increased over three months of rehabilitation. Expected caloric expenditure was 3009 calories per day.
> [...] The men experienced profound physical and psychological changes. Among the most consistent findings was the constant feeling of cold experienced by the participants. As one explained, "I'm cold. In July I walk downtown on a sunny day with a shirt and sweater to keep me warm. At night my well fed room mate, who isn't in the experiment, sleeps on top of his sheets but I crawl under two blankets."
> Resting metabolic rate dropped by 40 percent.
> Interestingly, this phenomenon is very similar to that of the previous study, which showed a drop of 30 percent. Measurement of the subjects' strength showed a 21 percent decrease. Heart rate slowed considerably, from an average of fifty-five beats per minute to only thirty-five. Heart stroke volume decreased by 20 percent. Body temperature dropped to an average of 95.8°F. Physical endurance dropped by half. Blood pressure dropped. Men became extremely tired and dizzy. They lost hair and their nails grew brittle.
> Psychologically, there were equally devastating effects. The men experienced a complete lack of interest in everything except for food, which became an object of intense fascination to them. Some hoarded cookbooks and utensils. They were plagued with constant, unyielding hunger. Some were unable to concentrate, and several withdrew from their university studies. There were several cases of frankly neurotic behavior.
Let me repeat a fragment of that from above: Resting metabolic rate dropped by 40 percent. If you just try to "overpower yourself to eat less", you will temporarily lose weight, but eventually you'll give in, and then your weight will return to a higher level than before - something that is also supported by scientific studies.
> It is absolutely irrelevant when to eat: only the amount of calories intake matters.
This is also false - eating continuously during the day leads to insulin resistance and weight gain, while eating the same amount of food in a smaller region, while not necessarily health, does not cause that effect.