7 Ways Your Body Is Telling You That You’re Likely Undereating, According to an Eating Disorder RD

With the rise of intuitive eating, we are now more aware than ever of how pervasive (and unconscious) diet culture programming can be. Loss of appetite, chronic history of dieting, medical conditions are just a handful of reasons why someone may be under-fueling. Whether it’s intentional or not, under-eating has serious consequences for our health. Our metabolism, brain health, organ functions, general stamina, and energy levels all rely on consuming enough calories to run optimally.

When you eat less consistently over time, your body has to adapt by reducing energy expenditure in other ways. Your metabolism may drop, your energy levels may sink, and you may notice that you develop a host of sneaky symptoms that don’t seem to have a designated root cause but are all signs of not eating enough: Constipation, feeling cold all the time, significant weight changes, or inability to lose weight are some of the physical symptoms you may notice when under-eating.

Furthermore, there are psychological symptoms that are just as noteworthy. You may find that you become preoccupied with thoughts about food, experience brain fog or lack of focus, or develop increased cravings for high-calorie foods. And remember: There are no weight restrictions around who can experience symptoms of under-shooting nutrition needs—meaning someone can be malnourished and not underweight.

Now, let’s dive into the signs of not eating enough and what to do instead

1. Low energy

Possibly the most obvious sign of not eating enough food, you may notice a decrease in your energy levels overtime. If you have been chronically under-eating, this may not be obvious to you though. Consider eating a balanced breakfast, lunch, dinner, and enough snacks to feel fueled throughout the day and notice whether or not you experience a change in your energy levels. “Every organ and muscle in your body needs nourishment to function, so it’s common to experience low energy levels and fatigue when you’re under-eating,” says Haley Bishoff, RDN, owner of Rūtsu Nutrition in Las Vegas. “You can think of your body like a car that needs gas in order to run—your body needs fuel in the form of healthy carbohydrates, proteins, and fats to create energy.”

2. Constipation

One of the telltale signs of not eating is constipation because with less food in your system, your body slows down digestion to try and absorb as much nutrition as possible from the food you are taking in. An early indicator that you aren’t getting the calories you need is a change in bathroom habits, according to registered dietitian nutritionist Amanda Liptak, RDN. “What goes in, should come out,” she says. “A sign of a healthy body and gut is having at least one bowel movement each day.” Bowel movements should happen with ease, not strain, Liptak adds. “If you notice that it’s suddenly harder to pass a bowel movement, the color, shape, or effort you are putting into eliminating waste from your body is more difficult, it’s time to take a look at your nutrition,” she says. “Up your calories slightly, along with dietary fiber and hydration, and see how much this makes a difference.”

3. Intense cravings and persistent thoughts about food

When you’re not taking in enough, it makes sense that our body will send you stronger signals, like cravings, to eat calorie dense foods. If you find yourself regularly craving foods that are high in fat, sugar, and calories this may be a sign that you’re not eating enough total food consistently throughout the day. Caroline Young, RD, owner of Whole Self Nutrition in Atlanta, an eating disorder nutrition expert says that in her practice, one of the number-one signs indicating under-eating is preoccupation with food. “Our bodies and brains are wired to keep us alive,” says Young. “So, if our bodies detect a famine in any form of under-eating, even in the case of subtle restriction, they send signals to our brains to generate consistent thoughts about food. If you are thinking about food all of the time, chances are high you are not eating enough.”

4. Struggling with mood changes

If you’ve ever felt “hangry,” you can imagine the impact of longer term restriction.  Even when it’s unintentional, under-eating has a large impact on our mental health. Our brain requires fuel just like the rest of our body throughout the day. Chronic patterns of under-eating can trigger mood changes like anxiety, depression, and mood swings. “We all need a variety of foods, and enough of them, to provide all the nutrients the brain and body need to function their best. If you don’t eat enough, you’re at greater risk of depression and anxiety,” explains Kim Kulp, RDN, owner of the Gut Health Connection in the San Francisco Bay Area.

5. Feeling cold all the time

Feeling cold all the time is a sign that you may be struggling with getting enough food. Without proper nutrition, the body’s thermoregulation, or ability to regulate your system’s internal temperature, is altered, and your core body temp can slightly trend down. You may feel cold because your body is working so hard to keep you warm without enough fuel on board.

6. Night time snacking habits

Night time snacking is (of course) completely healthy, but excessive hunger at night can be a sign that you need more day time calories. Eating enough throughout the day can help you feel both full and satisfied and not need large amounts of food at night.

Further, night time eating can be a vicious cycle, as you may wake up the next morning and feel like skipping breakfast. Thus, repeating the restrict-then-overeat cycle the next day. “One of the most common signs my clients were under-eating is excessive nighttime snacking,” says Kelsey Kunik, RDN and nutrition advisor for Zenmaster Wellness. “Avoiding or numbing hunger signals during the day with cups of coffee, diet coke, gum, and more while only eating light daytime meals will send your body into the evening desperate for the energy it needs.”

7. Missing your cycle

For women, amenorrhea, or missing your period more than one time, is a surefire sign that something is awry. Our monthly cycle can be a signal of being properly fueled. When you are energy deficient, the body does not feel it would be safe to get pregnant, thus, it removes the ability to conceive by altering your cycle and shortening or removing your period.

Under-fueling and missed periods can be especially tricky in athletes who have steep calorie needs. With increased amounts of exercise, fueling properly becomes even more important. Gaining your cycle back consistently is a wonderful sign that you are starting to eat enough.