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Page 22 | Abby's Magazine - www.AbbysMag.com LEPTIN- A MASTER HORMONE THAT CONTROLS WEIGHT, CRAVINGS AND MORE Leptin (Greek "leptos" meaning thin) discovered in 1994, regulates energy intake and expenditure, including appetite and hunger, metabolism and behavior. It is one of the most important adipose (body fat) derived hormones. Leptin functions by binding to the leptin receptor. Leptin is a hormone made by white adipose tissue that circulates in the blood and acts on the brain to regulate food intake and body weight. When fat mass falls, plasma leptin levels fall stimulating appetite and suppressing energy expenditure until fat mass is restored. When fat mass increases, leptin levels increase, suppressing appetite until weight is lost. This physiological system ensures that total energy stores are stably maintained within a relatively narrow rang. Leptin also regulates many other physiologic systems that play a critical role in the adaptive response to starvation. Serum levels of leptin are higher between midnight and early morning which could have an effect in suppressing appetite during the night while sleeping. The rhythm of plasma leptin can be modified by meal-timing indicating that plasma leptin is linked to meal timing. Leptin Resistance The problem is not in the production of leptin, but rather, studies show that the majority of overweight individuals who are having difficulty losing weight have a leptin resistance, where the leptin is unable to produce its normal effects to stimulate weight loss. This leptin resistance is sensed as starvation, so multiple mechanisms are activated to increase fat stores, rather than burn excess fat stores. Leptin resistance also stimulates the formation of reverse T3, which blocks the effects of thyroid hormone on metabolism. So, the person is eating excess food but the body thinks it is starving and tells the person to eat more. It's easy to see how this cycle could contribute to weight gain! Factors that Contribute to Leptin Resistance As with all hormone issues, Leptin resistance is a complex issue with no singular cause, but there are many factors that can negatively impact Leptin levels including: • Fructose consumption (especially in forms like High Fructose Corn Syrup) • High stress levels • Consumption of a lot of simple carbs • Lack of sleep • High insulin levels (vicious cycle here) • Overeating • Exercising too much, especially if your hormones are already damaged How to Fix Leptin Resistance This is a complex problem, but not an irreversible one. Dr. Jack Kruse (a neurosurgeon) and Stephan Guyenet (an obesity researcher) have both written in depth about the causes of leptin imbalance and ways to reverse it.