In our vocabulary, the word “diet” has come to mean a painful, restrictive eating plan designed to lose weight very quickly and easily as long as the plan is followed. There are all kinds of diets out there from the grapefruit diet to the Atkins Diet to the cabbage soup diet.
Generally, people try to lose weight, and look for a certain “diet” to follow for some time, lose a bit of weight, get off the diet, overcompensate for all of the delicious food they were denying themselves, and gain more weight than prior to starting the diet. Then eventually they realize they have to lose some weight again and start the process all over. This leads to the very dangerous “yo-yo” (up and down) weight change that is often seen in people with this type of behavior.
A lifestyle change, however, is very different. Rather than looking at a short term goal such as weight loss, one would look at a more long term goal such as being healthy (part of which would be staying within a healthy weight range). Furthermore, the strategy used to achieve this goal would have to be sustainable, meaning that if the person trying to change his/her lifestyle absolutely loved chocolate and could not give it up, maybe they could find a way to limit their intake, not stop cold turkey.
Incremental lifestyle changes may not seem like big enough changes to really affect your health, and they are unlikely to give the quick results everyone craves (and may occur on the mass marketed “diets”), but they work much more efficiently when looking at the big picture.
As an example, imagine that you are the person who needs to get that chocolate fix in the above example. Every time you go to the store for any reason, you buy a king size snickers bar. One day, you realize enough is enough, and you decide to take matters into your own hands and lose weight (action stage of the Transtheoretical Model of Health Behavior Change).
If you were to follow a strict Atkins style diet, you would completely stop eating chocolate. Every visit to the store would be unbearable because you would have to see all of the delicious candy bars and not be able to eat any of them. However, you would be losing weight…for a few months. It would then become too much and you would go on a candy binge, eating many many candy bars all at one time, giving up on this whole “diet” thing, because it is just too hard, not for you, etc…
On the other hand, as part of a commitment to a change in lifestyle, you may begin by only eating three candy bars each week, and continue until you are down to one a week. You may perhaps then decide to change from snicker’s king size to some kind of dark chocolate.
Therefore by looking at the long term horizon, you are not denying yourself something which is important, only altering what you are eating. It is not weight loss that is the goal, it is being healthy. Weight loss is a byproduct.