On the surface, appetite is one of the body’s simplest functions. When your belly empties, you feel hunger; when it’s full, you feel satisfied. Yet though this is the basic mechanism behind appetite, there’s more to the story of hunger and fullness than just the contents of your stomach. Feeling satiated (or not so satiated) is an intricate dance of hormones, environment, activity levels, and more. In fact, so many factors affect appetite that it can sometimes be hard to tell whether it’s really time to eat or time to meet another need.
Want to tune into your body’s hunger cues with greater accuracy? It helps to get to know which surprising factors could be pulling the strings. The following seven sneaky culprits can throw your appetite for a loop.
- ABOUT OUR EXPERTS: Kelsey Kunik, R.D.N., is a registered dietitian with Graciously Nourished. Wan Na Chun, R.D.N., C.P.T., is a registered dietitian with One Pot Wellness.
1. Your Sleep (Or Lack Thereof)
If you’ve ever felt extra peckish after a night of tossing and turning, it’s not all in your head. Science shows there’s a strong link between the quality of our sleep and the intensity of our appetite.
Experts say this connection all comes down to hormones: “Quality, restful sleep helps your body produce the right amount of the hormones that help to regulate appetite,” explains dietitian Kelsey Kunik, R.D.N., of Graciously Nourished. “Animal and human studies have both found a relationship between sleep deprivation and changes in [appetite-influencing] hormones like insulin, ghrelin, and leptin.”
Read More: Make These Changes to Your Evening Routine to Sleep Better
The result? Even one night of disrupted sleep can be enough to boost calorie intake the next day, according to research. Add that to the list of many good reasons to get enough shuteye.
2. Your Workout Routine
You don’t have to be an exercise scientist to understand the interplay between working out and appetite. When you exercise, you burn calories, triggering hunger. Some high-intensity activities like running and cycling burn energy to the tune of over 1,400 calories per hour! Though researchers don’t fully understand the mechanism, the theory goes that different types of exercise stimulate two different hormones: ghrelin and peptide YY, which increase (or sometimes actually decrease) hunger.
Of course, it’s important to refuel with the calories and macros you need after a tough workout—but there’s also a risk of overdoing it. “While your body does need more calories when you’re active, be mindful of what you’re eating to help prevent overeating,” says Kunik. Research shows that it’s common to overcompensate by eating larger portions post-exercise.
Your move here: Include plenty of protein and healthy fats in your meals, suggests Kunik. This will support repairing muscle and building strength, and help you feel more satisfied and avoid overeating. Protein is the most satiating of the three macronutrients, while fat can help regulate appetite via hormonal pathways.
3. Your Hormones
Those sneaky hormones strike again! For women, the menstrual cycle can affect hunger hormones and cause swings in appetite. “During the follicular phase of the menstrual cycle, levels of ghrelin (the hormone that stimulates appetite) may decrease, which decreases the sensation of hunger and energy intake,” says dietitian Wan Na Chun, R.D.N., C.P.T., of One Pot Wellness. As such, women may feel noticeably less hungry after menstruating.
On the other hand, in the week before menstruation, higher progesterone levels can stimulate appetite, causing the notorious cravings many experience before a period’s arrival.
It’s not just the women whose appetites can be affected by hormones, either. Anyone with an overactive thyroid can experience elevated hunger as a symptom. If you’ve noticed an unexplained uptick in your desire to eat, it may be time to ask your doctor to check your thyroid.
4. Your Meds
Looking for the source of a suddenly ravenous or absent appetite? Check your medicine cabinet. Various prescription meds can do a number on your hunger. “Some common medications, such as bupropion and naltrexone, generally decrease appetite and reduce food cravings,” says Chun. “Other medications that can affect appetite include antidepressants, antipsychotics, steroids, and some seizure medications.”
To get to the bottom of the medication-appetite question, Chun advises monitoring your eating habits after starting any new drug. “This can be easily done by keeping track of any changes in a journal,” she says. If you’re concerned about any shifts you notice, have a conversation with your healthcare provider.
5. Your Caffeine Intake
That third cup of afternoon joe might do more than keep you awake—it could perk up your appetite, too. “Caffeine intake can suppress appetite in the short-term, but this may also lead to increased hunger and overeating later on,” says Chun. Keeping your caffeine intake moderate allows you to feel hungry when your belly is empty so that you’re not raiding the fridge a few hours later. The FDA recommends a limit of no more than 400 milligrams (about four to five cups of coffee) per day.
Read More: 5 Signs You Need a Break From Caffeine
6. Your Environment
When you’re feeling snacky, take a minute to consider: Are you actually hungry, or are you responding to appetite-boosting stimuli? What’s going on around you can tip the scales of appetite more than you might realize. “Who you eat with, the environment you eat in, and the types of foods you surround yourself with can all impact how much food you eat,” says Kunik. For example, eating in loud, chaotic settings can make it difficult to pay attention to your own hunger cues and feel satisfied by the food you’re eating. The same goes for being surrounded by food (like at a party), dining with folks who eat significantly more or differently than you, or eating in front of your phone or TV.
Kunik’s tip for outwitting external influences? “Try to find somewhere quiet to eat your meals so you can fully relax and pay attention to your food as you eat,” she suggests.
7. Your Stress Levels
Raise your hand if you’ve ever done any stress eating. (Hmm, all of us, then?) Mental and emotional troubles can put appetite into overdrive—or into hibernation. “The impact depends highly on the individual, as some individuals can have an increased or decreased appetite as a result of stress,” says Chun. In fact, according to research from 2018, acute stress typically results in decreased appetite, while long-term stress usually leads to overeating. But anything is possible. “The changes that stress has on appetite are often related to the complex interplay of hormones and neurotransmitters in the body,” Chun explains.
If you find yourself chowing down more or less than usual, check in with yourself about stress levels. Maybe appetite changes would be better addressed with a relaxing bath or a long walk than with a bowl of ice cream.