Published September 16th 2013
Leptin is a hormone which is produced by the adipocytes, also known as the fat cells. This hormone is very important when it comes to regulating food intake and energy storage. Leptin is connected with obesity, and in this article I’ll also explain how it relates to thyroid health.
But let’s first learn a little more about leptin. As I just mentioned, leptin helps with regulating food intake and energy storage. It actually helps to suppress appetite, and this helps one to maintain a healthy weight. However, while leptin is important, it is also important that the leptin receptors are working properly. When someone has healthy levels of leptin and the receptors are functioning properly, this results in a decrease in appetite. On the other hand, if someone has a leptin deficiency, this will lead to a voracious appetite. For example, when someone eats a very low calorie diet, the body will increase the secretion of leptin in order to increase their appetite so that they will eat more.
Weight gain results in an increased plasma leptin level, while weight loss results in decreased plasma levels of leptin (1) [1]. So in people who are obese the circulating level of leptin is increased, and it has been established that obese patients are leptin-resistant (2) [2]. Leptin resistance is the failure of elevated leptin levels to suppress feeding and mediate weight loss (3) [3]. Leptin receptors are found in the brainstem, hypothalamus, and distributed reward centers of the CNS (4) [4]. A number of mechanisms weaken leptin signaling and lead to leptin resistance in obesity (5) [3].
Leptin and Fertility Leptin also plays a role in fertility (6) [5]. There is a relationship between the secretion of leptin and disturbances in menstruation, as well as in the pathogenesis of polycystic ovarian syndrome (6) [5]. Leptin deficiency leads to infertility due to a lack of appropriate pubertal development and inadequate synthesis and secretion of gonadotropins and gonadal steroids (7) [6]. Leptin receptors are expressed in many organs and tissues, including those related to the control of reproductive physiology (7) [6].
Leptin and Immunity Leptin plays an important role in immunity. Early findings of increased leptin production during infection and inflammation and dysregulated immune response in leptin signaling-deficient mice provide strong evidence for the involvement of leptin in the immune responses (8) [7]. There is also evidence that leptin is involved in the pathogenesis of certain autoimmune conditions (8) [7]. This of course could be an important factor in those people with Graves’ Disease and Hashimoto’s Thyroiditis.
How Does Leptin Relate To Thyroid Health? Hypothyroidism is usually associated with changes in body weight and energy expenditure. A recent study looked at the relationship between obesity, thyroid function, and autoimmunity (9) [8]. The study discussed how there is a relationship between obesity and thyroid autoimmunity, with the hormone leptin playing a key role in linking these conditions. The study discussed how “leptin resistance may mitigate leptin deficiency and enhance autoimmunity in obese subjects, and the development of resistance to the weight-lowering effects of leptin might be initiated by activation of inflammatory signaling”.
So what does this mean? Essentially what this is saying is that the inflammatory component of the autoimmune response might lead to leptin resistance, thus causing obesity. However, obesity itself can potentially lead to thyroid autoimmunity. With someone who already has an autoimmune thyroid condition such as Graves’ Disease or Hashimoto’s Thyroiditis, the goal is to suppress the autoimmune response, and addressing the inflammatory component is a big factor in this. By addressing the inflammatory component, this not only can help to suppress the autoimmune response, but in turn can help to correct leptin resistance, thus making it easier to lose weight.
What Can You Do To Address The Inflammatory Component? When dealing with any inflammatory condition, eating well is of course very important. Eating plenty of fresh vegetables is very important, and some healthy fruits are usually fine to eat as well. You want to avoid pro-inflammatory foods, which pretty much includes all fried foods, refined foods, and cooking foods at high temperatures is also something you want to avoid. While eating meat is fine, eating a lot of meat can be pro-inflammatory due to the formation of arachidonic acid, and so you don’t want to overdo it in this area. The nightshade vegetables can also cause inflammatory problems with some people, and these foods include tomatoes, eggplant, peppers, and potatoes.
Certain supplements can help with the inflammation. There is a lot of research which shows the anti-inflammatory effects of omega 3 fatty acids. I prefer fish oils, although krill oil can also be beneficial, and if someone is a vegetarian then flaxseeds or chia seeds are an option. There are also many clinical studies showing the benefits of both turmeric and resveratrol, and so these both can greatly help with the inflammatory component. Vitamin D has anti-inflammatory effects, and so if someone is vitamin D deficiency then this should be addressed.
In summary, leptin is a hormone that is secreted by the fat cells of the body, and helps to regulate the person’s appetite and energy storage. As a result, leptin plays an important role in maintaining weight, but also is important when it comes to fertility and immunity. With regards to thyroid health, leptin resistance might actually increase the risk of developing an autoimmune thyroid condition in people who are obese. For those who already have an autoimmune thyroid condition, the goal should be to address the inflammatory process, which will help to suppress the autoimmune component of the condition.