What Does Malnutrition Feel Like in Adults? Recognizing the Signs

October 22, 2025 •

4 min read

According to Age UK, approximately one in ten older people are malnourished or at risk in the UK alone, demonstrating how common yet often overlooked this condition can be. Understanding what does malnutrition feel like in adults is crucial, as the symptoms are frequently subtle and can be misattributed to other health issues.

Quick Summary

Malnutrition in adults can manifest through a wide range of physical, mental, and emotional symptoms, including persistent fatigue, muscle weakness, mood changes, and compromised immunity. Observable signs like unintentional weight loss, brittle hair, and slow wound healing are also key indicators.

Key Points

Persistent Fatigue: Unexplained and ongoing tiredness is a primary feeling of malnutrition, resulting from the body lacking sufficient energy from food.
Muscle Weakness: A noticeable reduction in muscle mass and overall strength, due to the body breaking down protein for energy.
Mental and Emotional Changes: Mood disturbances, including irritability, apathy, and depression, can result from nutrient deficiencies impacting brain function.
Compromised Immune System: Malnutrition weakens the body's defenses, leading to frequent illnesses, recurrent infections, and slow wound healing.
Feeling Cold Constantly: The body’s inability to produce enough heat due to lack of nutrients leads to a persistent sensation of being cold.
Appetite Changes: A significant loss of appetite or a complete lack of interest in food and drink is a key behavioral symptom.
Unintentional Weight Loss: The gradual loosening of clothes, belts, or jewelry can signal a loss of body fat and muscle mass.

Malnutrition is Not Always Obvious

Malnutrition is a state where a person's diet does not provide enough nutrients for optimal health, or provides too much of a certain nutrient. While many people associate malnutrition with severe weight loss, it can affect individuals of any size, including those who are overweight or obese but lack essential vitamins and minerals. Recognizing the symptoms requires paying close attention to changes in both physical and mental well-being, as the body's systems begin to fail under nutritional stress.

The Physical Sensations of Malnutrition

When your body is starved of the necessary fuel and building blocks, it begins to break down its own tissues for energy, leading to a cascade of physical sensations and symptoms.

Persistent Fatigue and Lethargy: This is one of the most common and earliest feelings of malnutrition. You may feel a constant, overwhelming tiredness that doesn't improve with rest, as your body lacks the calories and nutrients needed for energy production.
Muscle Weakness and Wasting: Protein is essential for muscle maintenance. Without sufficient intake, the body breaks down muscle mass to get the protein it needs, resulting in a noticeable decrease in strength and physical capability. This muscle wasting is often visible around the temples, clavicles, and thighs.
Constant Coldness: Nutrients play a key role in thermoregulation. A body running on empty cannot produce enough energy to keep warm, leading to a constant feeling of coldness, even in warm environments.
Changes in Skin, Hair, and Nails: A lack of nutrients like protein, iron, and zinc can manifest externally. You might notice dry, flaky, or pale skin; hair that becomes thin, brittle, and easily plucked; and nails that are ridged, brittle, or spoon-shaped.
Frequent Infections and Slow Healing: A weakened immune system is one of the first processes to suffer from malnutrition, making you more susceptible to illnesses and infections. Furthermore, wounds, cuts, and scrapes may take significantly longer to heal, as the body lacks the resources for tissue repair.

The Mental and Emotional Effects

Malnutrition is not just a physical problem; it profoundly impacts mental and emotional health. The brain requires a steady supply of nutrients to function correctly, and a deficiency can cause significant cognitive and mood disturbances.

Poor Concentration and 'Brain Fog': Nutrient deficiencies, particularly in B vitamins and iron, can impair cognitive function, leading to difficulty concentrating, memory problems, and a general feeling of mental fogginess.
Irritability and Apathy: Malnutrition can affect neurotransmitter production, leading to mood swings, increased irritability, and a general lack of motivation or apathy towards daily activities and interests.
Anxiety and Depression: Studies have shown a strong link between poor nutrition and mental health conditions. Deficiencies in nutrients like vitamin B12, folate, and omega-3 fatty acids can increase the risk of developing symptoms of anxiety and depression.

Early vs. Advanced Malnutrition Symptoms

Recognizing the stage of malnutrition is important for treatment. The symptoms often progress gradually, and subtle changes can be missed initially.


Symptom Category	Early Malnutrition	Advanced Malnutrition
Physical Sensations	Mild fatigue, occasional feeling of coldness, reduced energy for vigorous activity.	Extreme fatigue, constant feeling of coldness, faintness, severe muscle weakness and pain.
Appearance	Subtle weight loss (less than 5% of body weight), slightly dry skin.	Significant, unintentional weight loss (over 10% in 3-6 months), visible muscle wasting, edema.
Immune Health	Taking slightly longer to recover from a cold or flu.	Recurrent infections, wounds that heal very slowly or not at all.
Mental & Emotional	Irritability, occasional trouble concentrating, reduced motivation.	Apathy, severe depression, significant cognitive impairment, loss of interest in food and life.
Digestive System	Changes in appetite, mild constipation or diarrhea.	Loss of appetite, digestive system atrophy, chronic constipation or diarrhea.

The Vicious Cycle of Malnutrition

Malnutrition can create a self-perpetuating cycle. A person with malnutrition may experience a loss of appetite, which in turn leads to a further decrease in nutrient intake. This can be compounded by other factors such as:

Underlying Medical Conditions: Diseases like cancer, Crohn's disease, or COPD can increase the body's nutrient needs or interfere with absorption.
Mental Health Issues: Conditions like depression or dementia can diminish motivation and make it difficult to remember or care about eating.
Social and Mobility Problems: Factors like living alone, social isolation, limited mobility, or financial hardship can all hinder access to and preparation of nutritious food.

Conclusion

Recognizing what does malnutrition feel like in adults is the first critical step towards recovery. The symptoms, from persistent fatigue and muscle weakness to mental and emotional distress, can be easily mistaken for other health problems, leading to a delay in diagnosis and treatment. If you or a loved one is experiencing unintentional weight loss, a marked decrease in appetite, or a combination of these physical and mental symptoms, it is vital to consult a healthcare provider. Early intervention and nutritional support can reverse the course of malnutrition and prevent more severe complications.

For more detailed information on a wide range of nutritional disorders, the National Institutes of Health provides comprehensive resources on nutrient deficiencies and their effects on the body.

Frequently Asked Questions

Yes, it is possible to be overweight or obese and still suffer from malnutrition. This occurs when a person consumes excess calories but lacks sufficient intake of essential vitamins and minerals, leading to micronutrient deficiencies and health complications.

The early signs of malnutrition can be subtle and include a reduced appetite or interest in food, a feeling of persistent tiredness or fatigue, and unintentional weight loss over a period of a few months.

Malnutrition can significantly impact mental health by disrupting the production of neurotransmitters required for mood regulation. Deficiencies in nutrients like B vitamins, iron, and omega-3 fatty acids are linked to symptoms of depression, anxiety, irritability, and poor concentration.

The body needs adequate protein and other nutrients, such as zinc and vitamins, to repair tissues and heal wounds effectively. When these are lacking due to malnutrition, the healing process is slowed down or impaired.

A reduced or complete loss of appetite is both a symptom and a cause of malnutrition, creating a vicious cycle. People may lose interest in food and drink, further worsening their nutritional status.

Yes, older adults are at a higher risk of malnutrition due to factors such as reduced appetite with age, limited mobility affecting food access, difficulty chewing or swallowing, social isolation, and certain medical conditions.

You should contact a healthcare provider if you experience unexplained, unintentional weight loss of more than 5% to 10% of your body weight over 3 to 6 months, or if you have persistent symptoms of fatigue, weakness, or mood changes.

Causes include poor dietary choices, medical conditions that affect digestion or appetite (like Crohn's disease or cancer), mental health issues (such as depression), limited access to nutritious food due to income or mobility, and alcoholism.

Yes, feeling cold frequently is a common symptom of malnutrition. The body needs calories and fat to generate heat, and when these are in short supply, the body's internal temperature can drop, making a person feel cold.