Based on the genes you inherited from your parents, you have a programmed weight range or set point for how much weight you should carry on your body. The part of the brain that controls this is called the lipostat.
Have you ever wonder why it can be so difficult to lose weight and so easy to gain it, or why it is so complicated to keep the same weight (weight maintenance) for a long time?
Studies show that the secret of a healthy weight and body seems to be located in the hypothalamus by a mechanism known as lipostat. Think of the lipostat as a little “device” in charge of setting a “preset weight” for all of us. It is known for years that physical activity and food intake regulation are the two most important factors involved in controlling our weight. But to regulate food intake, the hypothalamus must alter appetite. Fat tissues release leptin that travels to receptors in the hypothalamus. The hypothalamus then releases chemical signals to suppress the appetite. The information regarding the general body health is communicated by both long- and short-term chemical signals from the brain and the gut. The receipt and integration of these signals mainly occurs in the hypothalamus, also known to play a key role in the regulation of many other body factors such as thyroid function, which controls metabolism and is related to the effectiveness of weight loss interventions.
Not giving enough time to the hypothalamus to memorize and preset your weight can actually be one of the big reasons why ~80% of the people fail on weight loss. The exact timing might vary depend on the person but experts suggests that anyone aiming weight loss success should allow between 6 months - 1 year for "weight presetting". In order words, whatever "ideal or target weight" you have in your mind, once you reach it, you should do your best to keep it (maintain) for at least 6 months to 1 year to avoid rebound after weight loss. This will give enough time to the hyphotalamus to do the job. Read more about the lipostat theory by clicking the link below