When you eat less consistently over time, your body must adapt by reducing energy expenditure in other ways. Your metabolism may decrease, your energy levels may decrease, and you may notice that you are experiencing a range of sneaky symptoms that don’t seem to have a specific root cause but are all signs of not eating enough: constipation, feeling cold all the time or big changes. Being overweight or not being able to lose weight are some of the physical symptoms that you may notice when you are undereating.
Moreover, there are psychological symptoms that are noteworthy. You may find that you are preoccupied with thoughts about food, experience brain fog or lack of focus, or have increased cravings for high-calorie foods. And remember: There are no weight restrictions on who can have symptoms of deficient nutritional needs — meaning a person can be malnourished, not underweight.
Now, let’s dive into the signs of not eating enough and what to do instead
1. Low energy
Perhaps the most obvious sign of not eating enough, you may notice a drop in your energy levels over time. If you are chronically under-eating, this may not be so obvious to you. Consider eating a balanced breakfast, lunch and dinner and enough snacks to feel energized throughout the day and see if 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 undereating,” says Haley Bishoff, RDN, owner of Rūtsu Nutrition in Las Vegas. “You can think of your body as a car that needs gas to run—your body needs fuel in the form of healthy carbohydrates, protein, and fats to generate energy.”
Constipation is a clear sign of not eating because with less food in your system, your body slows down digestion to try to absorb as much nutrition as possible from the food you eat. An early indicator that you’re not getting the calories you need is a change in bathroom habits, according to registered dietitian Amanda Liptak, RDN. It says: “What goes in, must come out.” “A sign of a healthy body and gut is having at least one bowel movement each day.” Liptak adds that bowel movements should occur with ease, not straining. “If you notice that it’s suddenly difficult to pass a bowel movement, the color, the shape, or the effort you’re making to eliminate waste from your body, it’s time to take a look at your diet,” she says. “Raise your calories a bit, along with dietary fiber and water, and see how much difference that makes.”
3. Cravings and constant thoughts about food
When you don’t take in enough, it makes sense that the body would send you stronger signals, such as 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 are not eating enough overall consistently throughout the day. Carolyn Young, RD, owner of Whole Self Nutrition in Atlanta, a nutrition expert in eating disorders, says that in her practice, one of the first signs of under-eating is a preoccupation with food. “Our bodies and brains are engineered to keep us alive,” Young says. “So, if our bodies detect starvation in any form of lack of eating, even with careful restriction, it sends signals to our brains to generate consistent thoughts about food. If you are thinking about food all the time, you are probably not eating enough.”
4. You struggle with mood changes
If you’ve ever felt “hungry,” you can imagine the impact of long-term restrictions. Even when under-eating is unintentional, it has a significant impact on our mental health. Our brain requires fuel just like the rest of our bodies throughout the day. Chronic patterns of undereating can lead to mood changes such as anxiety, depression, and mood swings. “We all need a variety of foods, and enough of them, to provide all the nutrients our brain and body need to function at their best. If you’re not eating enough, you’re More likely to suffer from depression and anxiety.
5. Feeling cold all the time
Feeling cold all the time is a sign that you may be having difficulty getting enough to eat. Without proper nutrition, the body’s thermoregulation, or the ability to regulate the system’s internal temperature, is altered, and the body’s core temperature can trend slightly lower. You may feel cold because your body is working hard to keep you warm without enough fuel on the plane.
6. Night snacking habits
Snacking at night is (of course) perfectly healthy, but excessive hunger at night can be a sign that you need more calories during the day. Eating enough throughout the day can help you feel full and satisfied and not need large amounts of food at night.
Moreover, eating at night can be a vicious cycle, as you may wake up the next morning feeling the urge to skip breakfast. Thus, repeat the cycle of restricting and then overeating the next day. “One of the most common signs that my clients have been undereating is binging on snacks at night,” says Kelsey Kunik, RDN and nutrition consultant for Zenmaster Wellness. “Avoiding or numbing out hunger cues during the day with cups of coffee, Diet Coke, gum, and more while eating only daytime snacks will send your body into the evening desperate for the energy it needs.”
7. Missing your period
For women, amenorrhea, or missing periods more than once, is a sure sign that something is amiss. Our monthly cycle can be a signal that we are fueling properly. When you are experiencing a lack of energy, the body does not feel that it will be safe to conceive, thus, it removes the ability to conceive by altering your cycle and shortening or removing your period.
Periods of under- and lost fueling can be especially difficult for athletes with acute caloric needs. As the number of exercises increases, fueling properly becomes more important. Consistently restoring your cycle is a great sign that you have begun to eat enough.