Raise your hand if you’ve ever glanced at the clock after powering through your to-do list only to realize you can barely remember when you last had a snack. Or you skipped breakfast because your well-intentioned plans to meal prep did not, well, go according to plan. No matter the reason, sometimes skipping meals is just a fact of life. And although it seems innocuous, experts are pretty emphatic about eating regularly because of the effects skipping meals can have on your body and mind. Here’s exactly what goes down (two experts used the term “hangry,” if that’s any indication).
As a general rule of thumb, experts say you should aim to eat every three to four hours.
Although the specific timing will vary from person to person, there are various reasons it’s smart to eat this often. “Eating regularly throughout the day keeps your metabolism running at full speed, prevents dips in your energy, keeps you alert and focused, and [can help keep] your weight steady by preventing overeating at later meals,” Brigitte Zeitlin, M.P.H., R.D., C.D.N., founder of the New York-based BZ Nutrition, tells SELF. It’s not like if you don’t eat often enough on one day, all your systems will immediately go haywire. But your body will react to the dearth of fuel in various ways.
And what if you don’t eat that often? For starters, your mental faculties might take a dive.
“The main fuel for your brain is glucose, which you get from eating foods—predominantly carb-rich ones,” Rachele Pojednic, Ph.D., assistant professor in the nutrition department at Simmons College and professor at the Harvard Extension School, tells SELF. Complex carbohydrates, like fruits, vegetables, and whole grains, are the most nutritious sources of glucose because they take a longer time to digest than refined carbs (plus they’re often loaded with other beneficial nutrients). Without a frequent carb supply, your blood sugar can dip too low, leaving you feeling sluggish, irritated, and like you can’t concentrate, says Zeitlin.
Then the physical and emotional symptoms start kicking in.
While you might not be able to concentrate on tasks like answering emails, but you sure will be able to focus on food. When you don’t eat often enough, “the feeling that you need to have something to eat takes over,” Lauren Harris-Pincus, M.S., R.D.N., owner of Nutrition Starring You, tells SELF, adding that craving food and not having it means it’s prime hanger time.
“Hormones like leptin, which is appetite-inducing, and ghrelin, which is appetite-suppressing, will change to indicate you’re hungry,” says Pojednic. When you don’t satiate that hunger, you might experience shakiness or sweatiness as a response.
After those hormones get thrown out of whack and ramp up your hunger, it’s hard to make healthy choices at your next meal.
“When people are super hungry, they tend to go for the carbs and sweets because those will raise their blood sugar,” says Harris-Pincus. Carbo-loading without nutrients like fat and protein to temper the rise in glucose can make your blood sugar spike, then crash—not ideal.
It’s one thing to not make healthy choices when you finally eat after skipping meals, but there’s another negative effect in play. “You are likely to overeat to make up for the lack of calories you took in throughout the day,” says Zeitlin. “That can cause nausea, constipation, bloating, and exhaustion.” Overeating usually happens because you’re taking food in way too quickly and ignoring your body’s satiety cues, habits that, over time, can lead to weight gain, says Pojednic.
That covers the short-term effects that can take place when you’re not eating regularly. But if it becomes a habit, you can inflict long-lasting damage.
Skipping meals can mess with your metabolism, says Pojednic. Note that this doesn’t happen immediately. “When we think about this idea that metabolism goes into ‘starvation mode,’ it’s not because you skipped lunch one or two days during the week,” Pojednic explains. “It’s a chronic low consumption of calories that takes months or even years.”
Also, when you don’t eat often enough, you may not get enough protein to keep up muscle mass—which helps rev your metabolism—and you probably won’t have enough energy to work out and either build more muscle or maintain what you’ve got. “Skipping meals doesn’t only affect the nutrients you consume, but your ability to exercise and lead a healthy life,” says Harris-Pincus.
Although determining exactly how often you need to eat takes some experimentation and is an individual thing, it’s worth figuring out what works for you. To get you started, here’s expert-approved advice on the best foods to eat at every time of day.