Leptin and Ghrelin: Two Hormones You Should Know About
There are two hormones you should be aware of if you feel you are constantly thinking about food! The first is Leptin - this is made by adipose (fat) cells and is responsible for inhibiting hunger. It tells your brain that you are not starving and keeps your metabolism fired up. Leptin is the "satiety hormone".
When you lose fat, your Leptin levels decrease. Your brain senses this and when the levels drop below a certain threshold it puts your body into a starvation state. Your body will stop some of the most ‘expensive’ metabolic processes which lowers your metabolism, meaning that you’re now burning less calories for the same amount of daily activity.
Ghrelin, on the other hand, tells your brain that you should eat food. For this reason it’s referred to, aptly, as the “hunger hormone”. Released primarily by cells in the stomach, Ghrelin travels to the brain where it interacts with the hypothalamus (the part that controls hunger) to create the sensation of appetite.
Ghrelin has a generally inverse relationship with Leptin. When your Leptin levels are high your Ghrelin levels are low, and vice versa.
Ghrelin has a very interesting quirk. It’s usually released when your stomach is empty, but its intensity is higher when you eat regularly . So if you always have lunch at, say, 1pm, you’ll release Ghrelin at 1pm every day to remind you it’s lunch time. It causes hunger at the times you usually eat. This is why some people can happily go until 4pm every day without eating, whilst others are ravenous by noon.
Despite this you can actually control your own production of Ghrelin by just not eating at certain times of the day. For instance if you start an intermittent fasting diet and you want to stop eating breakfast, you’ll be hungry for the first few days, but your production of Ghrelin will start to down regulate almost immediately. Each day you go without that meal you’ll feel less hungry at that time in the future.
To summarise this Ghrelin makes you hungry. If you are on a restricted calorie diet and eating little and often, Ghrelin will continue to make you feel hungry.
Intermitent fasting is a good way to control Ghrelin. By this I mean eating the same amount of calories you would over the day during 8 hours and not eating (or drinking anything majorly calorific) during the 16 remaining hours. Your body will get used to not eating until a certain time and consequently you will not feel hungry until the time you break your 16 hour fast which should be around the same time every day.