Diets and Dieting - Can a Diet Be Healthy?
"Dieting is the practice or habit of eating (and drinking) in a regulated fashion, usually with the aim of losing weight." -- wikipedia.org
This definition reflects the current lay public's idea rather than one of nutritionists and dietitians. Generally speaking, dieting is a more or less consistent way of eating. A kid can say "I'm on McDonald's diet" and make no error in this statement.
An interesting consequence of the commonly accepted definition's standpoint is a doubt that a diet can be healthy. Because to lose weight, one should go on a reduction diet and there's no reduction diet that would insure adequate nutrition.
The matter is, the human body is designed to get all needed nutrients coupled with much more energy (calories) than the body of modern man can burn by physical efforts of everyday living. This is why increasing physical activities by exercising more plus a diet works better than any of these alone.