Hunger Hormones & How They Affect You
There are numerous hormones that impact hunger in somehow with around 15 assuming a part in your general yearning levels. For this article, we will concentrate on the 3 noteworthy players: Leptin, Ghrelin, and Neuropeptide Y (NPY). These 3 hormones are the real players with regards to long and transient yearning levels.
Hunger Hormone #1: Leptin
Leptin likes to keep the amount of fat you have at a constant level. As such, we’ll give Leptin the nickname, “Leveling Leptin” and say that it likes to act as a thermostat with regards to your body fat.
Leveling Leptin is primarily released from your fat cells and acts on your brain to tell your body how many calories you’re taking in. When the amount of calories you’re eating equals the amount of calories you’re burning, leptin stays at a constant level and “fullness signals” tell your brain not to overeat or under-eat. When you go on a diet, especially a crash diet, leptin levels will drop and the “fullness” signal does not get to your brain as strong or as often. This causes an increase in hunger, as “Leveling Leptin” tries to save you from starvation, or your body’s perceived starvation.
Leptin in essence is trying to save your life, which, a couple of hundred years ago, was essential for survival. But, in today’s society with more than enough food, what you get is an increased desire to eat. How well you deal with these lower leptin levels and concurrent higher hunger signal can often have a huge impact on how effectively you keep the weight off in the long-run. In addition to hunger, Leptin also has a powerful effect on your overall metabolism, exerting effect on your thyroid hormones. Leptin influences both the total amount of thyroid hormone released and how effectively you convert inactive T4 to the active T3.
Besides the overall amount of leptin given off by fat cells, how well your brain reacts to the leptin signals (leptin sensitivity) plays an important factor in overall body fat levels and obesity. For example, both Insulin and Leptin tend to be released during a high-carbohydrate meal. Both of these hormones in unison help to shuttle the glucose in your blood into either fat or muscle cells (insulin), while leptin tells your brain that you’re full and you don’t need to eat more.
When your cells are not reacting to the signals being sent, then you are said to have some sort of resistance. When someone has insulin and leptin resistance (as they tend to go hand and hand) it means your cells do not react appropriately to the signals being sent. Therefore, both glucose and insulin stay in your blood longer, blunting fat loss. Leptin, meanwhile, is not getting to your brain causing its “fullness signal” not to be heard, putting you into a potential vicious cycle of hunger and over-eating.
Hunger Hormone #2: Ghrelin
I first heard of Ghrelin during a presentation by Dr. Len Kravitz where he described this hormone as being elevated every time you’re hungry. As such, the nickname he used and that I’ll use in this article is “Growling Ghrelin.” Growling Ghrelin is an appetite-inducing hormone and when its levels are high, you crave something sweet, which after you eat will help lower your “Growling Ghrelin” levels. Ghrelin levels are high before a meal and drop after a meal.
Hunger Hormone #3: Neuropeptide Y (NPY)
As powerful as growling ghrelin is on appetite, NPY may be even stronger. For example, rats given an injection of NPY will crave sugar water over sex. The primary trigger for its release is calorie restriction and, specifically, low leptin levels. If you’ve ever seen someone eat a massive amount of food at one sitting, it was probably due to NPY’s effects, as NPY’s primary job is to delay the feeling of fullness throughout a meal. In other words, high NPY levels will decrease the feeling of fullness from a meal. In addition to appetite-inducing reactions in the body, NPY also has nutrient partitioning effects which tells your body where and how to store extra calories as either fat or muscle. Basically high levels of NPY will not only cause you to be less full from the meals you eat, but the calories you eat will be preferentially stored as fat. Leptin helps to inhibit the firing of NPY, shutting off the signal to eat.6
Leveling Leptin tells your body that it’s full and when it’s high you feel full and satisfied from eating. When you have Leptin resistance, your body is not accurately reading those signals of fullness causing you to be hungrier, more often.
Growling Ghrelin and NPY both increase appetite and when they are chronically high, you have an increased appetite, crave sweets, tend to eat more at meals, and have an increased risk of storing the calories you eat as fat.