There are two hormones involved in suppressing and raising your appetite: grehlin and leptin. Ghrelin is the so-called “hunger hormone.” It’s responsible for stimulating hunger and subsequently letting you know when it’s time to eat, increasing energy stores, and depositing fat. The hormone is released from cells in your stomach, then travels and interacts with your brain’s physiological eating center (the hypothalamus) and pleasure centers.
Naturally, your ghrelin levels will fluctuate throughout the day, rising before a meal and plummeting after, so as you'd expect, it's a key hormone for guys trying to burn fat and manage their weight. Ghrelin increases your appetite, slows metabolism, and decreases your body’s ability to burn fat, according to the Obesity Action Coalition—making it a key player in the battle for weight loss.
Leptin, on the other hand, is the “stop-appetite hormone” that signals your brain to reduce its appetite and burn more calories. It’s produced in fat cells and helps mediate weight loss by decreasing your hunger, food consumption, and increasing energy expenditure. Contrary to what you might expect, though, obesity is linked to unusually high concentrations of hunger-blocking leptin. Researchers believe these high concentrations make the receptors for leptin inactive, impairing its ability to eliminate excess fat. In essence, such high amounts of leptin essentially desensitize the body to it, meaning you can't take advantage of its signaling.
Feel like you’re constantly fighting a losing battle with your hunger? We’ve got the most common reasons you’re raising ghrelin (your hunger hormone) without even realizing it. Identify your problem habits, then biohack your appetite for good.
You're not sleeping enough
If you get a full night's sleep, you probably won’t be hungry when you wake up. That’s because during sleep, your body tamps down on ghrelin. A study in the journal PLoS Medicine showed a strong correlation between short sleep duration with high levels of hunger-inducing ghrelin, low levels of satisfaction-inducing leptin (and obesity). So get to bed, or you'll suffer defeat in the battle of the bulge.
You're consuming too much fructose
You know to avoid soda and snack foods laden with fructose, but you probably don’t think about other sources of the sweet stuff (like fruit juice and honey), which are vital to your health in small doses. But fructose prevents leptin and insulin from elevating back to normal levels after you eat, while simultaneously increasing ghrelin and triglycerides (blood lipid), according to research from the American Society for Clinical Nutrition. In the short term, you’re stuffing your face with food; in the long term, you’re facing weight gain and insulin resistance.
You're on a low-cal diet
When you lose weight via a calorie-restricted diet, you lower your circulating leptin levels and increase ghrelin (thusly increasing your appetite). A lot of people end up gaining a lot of weight back after they get off super-limiting diets; if they restricted fat in their diet, on the other hand, they’d have lowered their body fat without increasing ghrelin/appeptite levels, according to research from the Journal of Clinical Endocrinology and Metabolism.
You're not eating frequently enough
Ghrelin runs (is produced and secreted) on a four-hour schedule, according to research published in The Journal of Clinical Endocrinology and Metabolism. So, in order to keep ghrelin levels in check, you need to eat within these parameters. Remember, ghrelin rises before a meal, so if no food comes to lower the levels, you run in to a nasty snowball-esque situation. But eating on this schedule isn’t out of the norm. If you eat three meals interspersed with one or two snacks, you ghrelin levels will stay balanced.
You’re not eating a high-protein breakfast
And the most satiating macronutrient is… (drum roll) protein! A study published in The American Journal of Clinical Nutrition found men who ate a breakfast high in protein, compared to a breakfast high in carbohydrates, had decreased ghrelin concentrations. Protein increases feelings of satiety and decreases the need for further food intake, partially because they can’t be stored in the body; our body metabolizes them almost immediately, but, unlike carbs, this digestion process takes longer.
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You're way too stressed
Chronic stress causes ghrelin to rise, according to research from UT Southwestern Medical Center. The good news: This increase in ghrelin helps to diminish behaviors associated with depression and anxiety. Bad news: Ghrelin causes you to overeat and ultimately gain weight (who hasn’t experienced stress munchies?). Your body's natural defense against stress is causing you to eat more, causing you to gain more, causing you to stress more. Talk about a vicious cycle.