http://www.google.com/search?hl=en&...eceptors+leptin

I don't know if this was posted before (if so I apologize), but I was reading some summaries of research concerning leptin and weight. Here are some interesting facts. Leptin is a hormone which is secreted by your bodies fat cells after eating a satisfying meal. Its job is to suppress appetite by making your sweet taste receptors less sensitive. Interestingly enough it only affects sweet sensations:
http://www.mercola.com/2000/oct/1/leptin_sugar.htm
"To investigate the effects of leptin on taste buds, researchers injected a group of healthy mice with leptin and gaged their reactions to sweet, salty, sour, and bitter substances. The mice were less interested in sweet tastes such as sucrose and saccharin after the injection but their reactions to other tastes were unaffected."

Researchers found that mice which had a genetic mutation on the gene re: leptin receptors became obese, since they were insensitive to leptins effects on appetite and therefore not satiated.

From this information, it is reasonable to conclude:

1) Your body naturally moderates its weight. Obesity is an unnatural disease. Your body probably likes to have a little bit of fat for the winter, but because natural weight moderating mechanisms exist it is safe to say your body feels too much weight is debilitating. When fat stores are excessively high, leptin excretion is also very high since it is a hormone secreted from fat cells. The more obese you are, the more your body is trying telling you to stop eating carbohydrate via leptin.

2) Your body recognizes the connection between weight management and sweet sensations. Isn't the body amazing? You're body knew all along what folks like Dr. A told us just a few years ago... foods that stimulate the sweet receptors encourage insulin production, which encourages weight gain and over eating, and discourages weight loss. The more fat you have, the more "anti-carb" hormone you produce as if to tell you: "Put down the bagel, you have too much fat on your body. "

3) For people who become obese, there is most likely a problem with leptin/leptin receptors. The early hypothesis was that obese people lacked leptin, and so they chronically over ate because of it. However, it is now known leptin is produced by fat cells and therefore most obese people (but not all, and these people lose weight with leptin injections) have an abundance of leptin. Now it is hypothesized that the leptin receptors are the culprit. As with other food related diseases such as diabetes, obesity probably caused and is caused by cellular insensitivity to this crucial hormone. Some people may be born insensitive to leptin, while others become insensitive after a lifetime of the cycle of obesity: high carb intake, binging on food, weight gain, and repeat, all of which cause high levels of leptin which burn out your leptin receptors just as high levels of insulin (caused by the same cycle) cause insulin resistance.
In the studies, the mice who were leptin-normal lost their appetite after leptin injections, but the mice with defective leptin receptors found leptin injections had no effect on appetite, and soon became obese.


The leptin research seems to in many ways validate not only the effectiveness of a controlled carbohydrate lifestyle, but the absolute necessity for many obese people. Carb junkies are very real, for some people just cannot control their appetite when it comes to sweets. It seems we are coded to understand carbs do things to our bodies which make us gain weight, which is why our natural defense against morbid obesity centers around a hormone which dulls the sweet taste receptors therefore making carbohydrates unappealing to eat. This is why some people can become obese, and others cannot, and why obesity runs in families (even when the environmental component is neutralized or circumvented, re: twin studies).
It really does seem necessary, more and more each day, to make atkins a WOL for most of us. We can never eat as much carbohydrate as the rest of the world, even if calorically the same as a protein or fat, because we will wind up over eating since most obese people were born with, or now have because of dietary abuse, faulty leptin receptors. For many of us, eating carbs is like drinking water.

This explains beautifully why many obese people can't stop eating carbs until the bag of chips is gone. The insulin spiking theory Dr. Atkins popularized only explains how unstable blood sugar causes us to over eat throughout the day, he never gave a physiologically real basis for over eating sweets before the spike happens. Leptin fills that gap.

It would seem many if not most people prone to obesity more than likely have become or were born insensitive to the effects of leptin, just as some people become insensitive to insulin. This is why moderating intake of not just genuine, but all sweet tasting carbohydrate would seem crucial to controlling obesity. People who stall on or over eat even mock carbohydrate are those poor folks who are leptin insensitive. Just the taste of sweets can cause hormonal reactions in the body.