The Helpful Ways Your Body Lets You Know You're Not Eating Enough

If you're looking for it, there's a wealth of information available for people who want to lose weight. From TikTok videos to articles on lifestyle and health websites, the resources are there for anyone who believes they're eating too much. But what about for those who aren't eating enough?

An under-eating problem can be a lot trickier to identify and rectify, thanks in part to false information that lists dangerously low calorie levels as "targets" for health and weight loss. Very low calorie or crash diets may be safe under doctor supervision for those with weight-related medical conditions, but for the average person, they often lead to side effects like fatigue and digestion issues, per WebMD.

Whether you're actively following a very low calorie diet or not, your body will soon give you hints that you aren't consuming enough food. Along with physical signs, like dizziness, low energy levels, disruptions to your reproductive cycle and compromised hair, skin, and nails, you may also experience mental health issues and develop an unhealthy relationship with food as a result of eating too little. 

If you need help with an eating disorder, or know someone who is, help is available. Visit the National Eating Disorders Association website or contact NEDA's Live Helpline at 1-800-931-2237. You can also receive 24/7 Crisis Support via text (send NEDA to 741-741).

Fatigue is often the first sign that you aren't eating enough. As Healthline explains, calories aren't just a "bad guy" to fear; they're units of energy. If you don't get enough of them, you won't feel energized.

Most healthy adults need a minimum of 1,000 calories a day just for their body to have the energy to perform the most basic of functions. This is known as your resting metabolic rate. Consuming less than this is likely to leave you feeling fatigued. You're going to feel even more tired if you aren't eating enough and are physically active during the day.

While it's common to experience energy dips at certain points of the day, even if you are eating enough, fatigue from low calorie consumption tends to last for a longer period of time. This type of low energy also isn't usually cured by simply sleeping it off. If your energy levels significantly improve after you eat, it could be a sign that you aren't consuming enough.

The effects of under-eating can show up through your reproductive health. If you experience periods, pay attention to your cycle. Not eating enough can cause your body to skip your period altogether. Severe calorie restriction can lead to your body stopping the production of the hormones you need to ovulate.

Menstruation expert and naturopathic doctor Lara Briden explains that this condition is called hypothalamic amenorrhea, and it's particularly common in young women. This is basically your brain's way of saying to your body that there's not enough food intake to sustain a pregnancy, which it does by cutting off access of the hypothalmus to the ovaries. That way, there's no way you can make a baby that you can't feed.

If you suspect that you are missing your periods because you're not eating enough, it's best to see a medical professional to get to the bottom of it. Ovulation should resume within six months of eating a minimum of 2,500 calories a day, with 200 grams of starch.

Struggling with brittle nails, thinning hair, or unusually sensitive skin? Under-eating can cause all these symptoms due to the lack of nutrition it leads to. In particular, protein and vitamin deficiencies have been shown to cause hair loss and sudden changes in hair structure, while a lack of vitamin E can mean that your skin is more likely to be damaged by UV rays, per MedicalNewsToday. Meanwhile, brittle nails that are constantly breaking is another indication that you aren't eating enough.

There are topical remedies that you can use to fend off all these symptoms, but the problems will reoccur (and likely get worse) as long as you continue to under-eat. However, you can apply target treatments in conjunction with increasing your calorie intake.

For brittle nails, you can try a nail hardener, and keep your nails away from damaging products, such as nail polish removers with acetone. Make sure that you're using plenty of SPF on sensitive skin, and use aloe vera to soothe irritations. With thinning hair, there are certain products you can use that promote thickness and fullness, including special shampoos and growth serums, like the Georgie Mane Hair Growth Spray. However, your best bet is to keep your hair in good condition by cutting off split ends and treating yourself to regular deep-conditioning treatments.

Not eating enough may cause insomnia, and not just because you can't stop thinking about food. According to clinician Chris Kresser MS, LAc, you may have trouble falling and staying asleep when you're not eating enough because of the consequences on your blood sugar.

When you are under-eating, your liver doesn't have enough glycogen to maintain a healthy blood sugar level. In response, your body releases stress hormones to create new glucose, and one of these is adrenaline. Another is cortisol, otherwise known as the stress hormone. When these hormones reach high enough levels in your body, they can stop you from falling asleep, or even wake you up in the middle of the night.

Kresser advises eating a bedtime snack an hour or two before bed, however if you're not used to late-night eating, you can start to address the issue by simply eating more during the day, or at dinner.

Theoretically, eating fewer calories than you burn off will cause you to lose weight. But some people find that even when they reduce their calorie intake, they still can't shed excess weight. According to healthcare provider Piedmont, not eating enough can actually make it harder for you to lose weight than following a healthy diet because severe under-eating can affect the rate at which your metabolism burns energy.

"If you're not taking in enough to meet your daily requirements, your metabolism may slow down as your body goes into conservation mode," revealed therapeutic dietician at Piedmont Lena Beal, MS, RDN, LD.

When this occurs, your body stores fat because it believes there's a lack of food available. In effect, it's working to protect you from famine. Dieters often observe this when they experience a plateau in their weight loss; there comes a point where they reduce their calories too much, so their body burns fat as slowly as possible to fend off starvation.

One of the psychological effects of not eating enough is developing an unhealthy relationship with food. Several factors can lead to binge eating, including restrictive diets and not consuming enough calories, per WebMD. By not eating enough, you may convince your brain that food is not always available to you, so when you do allow yourself to eat, you feel the need to eat a lot more than you need.

Consciously being on a restrictive diet where you don't eat enough calories will often set you up for failure, because naturally, low calorie targets are hard to stay under. Not following your diet (because it's basically impossible) can cause you to feel guilty, which can also lead you to binge eat without control. The line of thinking is usually: "I've already messed up my diet today, so I might as well enjoy it before I start again tomorrow."

As WebMD explains, Binge eating is different from over-eating in that it is typically accompanied by feelings of shame. Most people binge eat in secret because they're so ashamed, and may eat to the point of being uncomfortable.

If you suspect your eating habits are something more serious, it's best to speak to a medical professional.

Not eating enough doesn't just make you physically tired; it can also give you brain fog that makes you feel mentally drained. Healthline points out that the nutritional deficiencies that tend to come from under-eating can lead to reduced cognitive function. If you're feeling especially forgetful, confused, or having difficulty concentrating on your tasks, these signs of low productivity can result from not eating enough.

Under-eating may also worsen symptoms of mental health conditions, which can impact cognitive function further. "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," owner of San Francisco's Gut Health Connection Kim Kulp, RDN, told Well + Good. "If you don't eat enough, you're at greater risk of depression and anxiety."

Not eating enough can also lead to increased irritability and mood swings. It may be a sign to investigate further if you notice that your mood seems to change rapidly beyond your control.

If you've ever told someone that you feel lightheaded, the first question they probably asked is, "Have you eaten anything?" It's not just an old wives' tale: Not eating enough really can cause you to feel dizzy. In fact, Nutrition Stripped explains that this is often one of the first signs that your body uses to let you know that it hasn't consumed enough.

Again, this symptom occurs because of your blood sugar levels. When your blood sugar drops too low, which can happen when you don't eat enough, the result tends to be a feeling of dizziness. The website recommends reaching for something with carbohydrates and protein when you start to feel lightheaded, as this will boost your blood sugar levels and keep them stable.

In severe cases of low blood sugar, also known as hypoglycemia, you may also experience sweatiness, shakiness, pale skin, and even a loss of consciousness, per MedicalNewsToday. You can keep glucose tablets or hard candy on you in case of extreme low blood sugar — which usually occurs as a result of diabetes, but can also occur in people without diabetes. If you are experiencing severe blood sugar dips, it's best to explore the causes with your doctor.