While obesity and related conditions are on the rise, the dangers of undereating are relatively overlooked. Undereating can have a range of adverse effects on a person's health and wellbeing.
In this article, we look at the risks and reasons for undereating. We also highlight nine signs and symptoms to look out for that may indicate a person is undereating.
Risks of undereating
A person is at risk of becoming underweight if they do not eat enough.
The primary risk of undereating is becoming underweight. This is typically determined using body mass index (BMI).
BMI uses a person's height and weight to give an approximate indication of whether a person is within a healthy weight range or not. Typically, a BMI of under 18.5 is considered underweight.
You can determine your BMI using one of our BMI calculators or charts.
The health risks associated with being underweight include:
- osteoporosis and bone fractures
- developmental problems
- a weakened immune system
- increased risk of surgical complications
- chronic fatigue
Reasons for undereating
Some people undereat intentionally, often as a result of adhering to restrictive diets or following popular health trends. Sometimes, these diets and trends can be misinterpreted or contain inappropriate nutritional advice, which can lead to undereating.
In other cases, a person might undereat due to an eating disorder or simply without realizing they are doing it. Sometimes people who have an abnormally high metabolism or high levels of physical activity do not eat enough to keep up with their body's demands.
Nine signs and symptoms of undereating
Signs and symptoms that a person may not be eating enough include:
Undereating can lead to a person becoming fatigued.
One of the most obvious and widespread symptoms that might indicate that a person may be undereating is constantly feeling tired.
A body gets its energy from the calories in the food and drinks a person consumes. The body requires a certain amount of energy calories to function properly. Functions include the basic and automatic bodily processes, such as breathing, as well as more complex processes such as actively thinking.
The number of calories needed to maintain a healthy weight will vary from person to person and depends on a variety of factors, such as body size, metabolism, and physical activity levels.
When someone is undereating, they are consuming fewer calories than their body needs to function correctly. This can have a severe impact on energy levels, causing feelings of physical tiredness and mental fatigue, which may impair a person's daily functioning.
Low energy levels can also have an adverse impact on physical activity performance and fitness. In a 2013 review, researchers found that people with an eating disorder consumed too few calories, which had a negative impact on physical fitness and sports performance.
2. Getting ill more often
Undereating can also lead to an imbalanced diet. This can mean that a person's body does not receive enough of specific nutrients to maintain a healthy immune system and fight off illnesses. It can also mean that illnesses, such as the common cold, last longer than they should.
Maintaining a healthful nutritional intake is particularly important for people who already have a weakened immune system, such as young children or older adults.
In one study, researchers found that providing people over the age of 65 with nutritional supplements resulted in significant improvements in the functioning of their immune systems.
3. Hair loss
Undereating can cause hair loss if nutritional intake is not sufficient. In a 2013 review, experts suggested that deficiencies in proteins, minerals, essential fatty acids, and vitamins can cause hair loss or other abnormalities, such as changes in hair color or structure.
4. Reproductive difficulties
When a person's body is not receiving enough nutrition, it prioritizes which processes to focus on maintaining, such as the life-supporting processes of breathing and blood circulation. As a consequence, sex hormone production can become impaired, which can reduce a person's desire for sexual activity and can interrupt reproductive processes.
Researchers have shown that a diet that contains insufficient calories can have an adverse impact upon reproductive functioning in both males and females. This can prevent pregnancies from occurring.
5. Constantly feeling cold
People require a sufficient level of calories to maintain a healthy body temperature. Consuming too few calories may cause a person's core body temperature to drop, which can create a constant feeling of being cold.
In a 2011 study, researchers found that people who consumed a restricted number of calories had a significantly lower core body temperature than those who consumed more calories.
6. Impaired growth in young people
Good nutrition is vital to proper development in young people. Undereating can cause nutritional imbalances that impair certain aspects of development, such as healthy bone growth.
During puberty, proper nutrition is essential to allow bones to grow and strengthen. Without this, a person might remain permanently smaller or weaker than their peers.
7. Skin problems
Skin problems are another sign that someone may be undereating. If a person's body does not get a sufficient amount of nutrients, such as vitamin E, it can lead to skin problems. Without enough vitamin E, a person's skin may become more easily damaged by inflammation or UV exposure.
Other vitamins necessary to maintain healthy skin include vitamin B-3 and niacin.
Depression is a highly complex mental health condition that can have a range of interlinked causes. It is not always possible to determine what is causing a person's depression, and the condition is not necessarily a sign of malnutrition. However, recent evidence has suggested there may be a link between poor nutrition and depression.
In a study of people who were pregnant, researchers found that symptoms of depression were associated with lower intakes of omega-3 fatty acid. In another study that used data from 31,424 adults, the authors found that those with depression had lower vitamin D levels than others.
Eating too few calories can also lead to constipation. People with constipation experience fewer bowel movements than other people. They may also have harder stools that can be difficult or painful to expel.
When a person undereats, their body has less food to convert into stools, which can cause constipation. Constipation tends to mean having fewer than three bowel movements per week.
How to deal with undereating
Eating foods that are high in protein will help a person increase their calorie intake in a healthful way.
Where possible, the most effective way for a person to tackle undereating is to increase the number of calories they consume. However, it is crucial to do this healthfully.
Foods high in sugar or unhealthful fats, such as trans-fats and saturated fats, contain a significant number of calories and may be a tempting way to increase overall calorie intake. However, these foods may also contribute to a whole range of other health risks, such as type-2 diabetes mellitus and cardiovascular disease.
Some tips for healthfully increasing the intake of calories include:
- eating meals more frequently throughout the day
- eating meals high in protein
- eating more complex carbohydrates, such as rice or pasta
- consuming more monounsaturated or polyunsaturated fats, such as nuts and avocados
- including a good selection of vegetables in the diet
- cutting down on cardiovascular exercise only if advised by a doctor
People with eating disorders, or other health conditions that contribute to undereating or malnutrition, should seek the advice of a doctor.
People who are worried that they may be undereating or who are experiencing any of the signs and symptoms discussed above should consider seeing a doctor or dietitian. A doctor or dietitian can advise a person on any symptoms they may have and can help formulate a diet plan that will increase calorie intake healthfully or increase the number of nutrients they consume.