11 Causes Of Unintentional And Unexplained Weight Loss In Kids

✔ Research-backed

Weight loss in kids may be considered if they are obese or overweight. Weight loss is when the body loses fats, muscles mass, and fluids, leading to total loss of body mass. Parents may consider intentional weight loss for their overweight or obese child under pediatric guidance. However, unintentional weight loss is abrupt and occurs due to underlying reasons.

The causes for unintentional weight loss are usually benign, manageable, and temporary. But if the child shows other accompanying symptoms, such as sudden loss of appetite and vomiting, it is good to consult a doctor to avoid potential complications.

In this post, we present the various reasons behind weight loss in children, symptoms of abnormal weight loss, and how to manage weight loss healthily.

In This Article

Possible Causes Of Unintentional Weight Loss In Children

Weight fluctuations among children are common and mostly benign. If your child loses a few pounds over time, you shouldn’t worry. Rapid development, puberty, and  exam stress could be the reasons for it. However, the list doesn’t end here. There are several other reasons for unexplained weight loss in children (1).

  1. Poor eating habits: Children should eat a well-balanced diet for proper growth, development, and sustenance. When children don’t eat properly or eat fewer calories than required, they lose weight. This condition is temporary and resolves as soon as the child begins eating a calorically optimum, well-balanced diet.
  1. Increased activity: Children indulge in different exercises and activities that increase the energy requirements of the body. If these requirements are not met, the child could experience weight loss. Parents should consult a qualified nutritionist to ascertain their child’s energy needs and get a suitable diet plan to maintain optimum nutrition levels.
  1. Stressful events: Divorce of parents, school or city change, and bullying at school are some of the stressful life events for children. Chronic stress accompanied by anxiety and depression can bring dietary changes, such as under-eating or loss of appetite, resulting in body weight loss. On the other hand, if children indulge in overeating or emotional eating, they can gain weight (2). Emotional eating due to stress is a common cause of childhood obesity.
Kids may lose weight due to stressful events that change their eating habits

Image: IStock

  1. Eating disorders: A systematic review and meta-analysis conducted by multiple institutions that included 63,181 participants from 16 countries showed that 22% of children and adolescents showed disordered eating, with a 30.03% incidence in girls and 16.98% in boys. Eating disorders, such as anorexiaiAn eating disorder marked by an unusually low weight and obsession with not eating food due to an intense fear of weight gain , are mental health problems that make a child indulge in an overly restrictive eating pattern that causes persistent and severe weight loss. It increases the risk of nutritional deficiencies, leading to further weight loss and growth problems. They are common in girls, especially in teenage.
  1. Short-term illness: Short-term illnesses, such as the common cold or stomach flu, can make children lose weight. Depending on the infection’s severity, weight loss can be mild or severe. Most children regain their lost weight as soon as their illness is treated and they are able to consume a regular diet. If they do not gain weight in given time of recovery, the doctor will look for underlying chronic illness.
  1. Oral or neurological issues: Children with oral problems, such as cleft palateiCondition characterized by gaps in the roof of the mouth and neurological concerns, such as cerebral palsyiMultiple disorders that collectively impact how well a person can move, balance, and maintain posture , can have feeding and swallowing difficulties. These difficulties could reduce their food intake, leading to unintentional weight loss (3).
  1. Gastrointestinal disorders: Gastrointestinal disorders, such as inflammatory bowel disease and celiac disease, often affect proper digestion and food absorption. Besides, they affect a child’s appetite, resulting in unintentional weight loss over time.
  1. Hormonal issues: Hormonal issues, such as Addison’s disease (adrenal insufficiency), hyperthyroidism, and type-1 diabetes, affect an individual’s metabolism, resulting in weight loss. Children with hormonal issues are likely to exhibit additional symptoms, such as abdominal pain, vomiting, and diarrhea, based on the disorder type.
Hormonal issues affect an child's metabolism, resulting in weight loss

Image: IStock

  1. Genetic disorders: Certain genetic disorders, such as cystic fibrosis, could cause unintentional weight loss. Cystic fibrosis features unintentional weight loss despite the child having an excess appetite. Some genetic disorders affect the healthy levels of enzymes in the body, causing muscle and fat loss, leading to weight loss (4) (5). Crohn’s disease is another example. It is a chronic condition that causes swelling in the digestive syste­m, especially the small bowe­l and large intestine. This causes issues in the mucus coating inside, which influe­nces a child’s growth. Persistent diarrhea due to Crohn’s could result in severe weight reduction (6).
  1. Medications: Medications for chronic or acute illnesses may cause weight loss as a side effect. If your child is on a certain medication and is losing weight consult your doctor. Anti-epileptic and some anti-depressants are often associated with weight loss (7).
  1. Substance abuse:Teens may indulge in substance abuse, such as narcotics and alcohol. Extended use of these substances could affect the physiological functions and suppress appetite, leading to unexplained weight loss (8).

protip_icon Did you know?
Serious diseases, such as rheumatoid arthritis, TB, or HIV, may also cause weight loss in children (1).

Besides these conditions, heart and kidney problems could cause unexplained weight loss. Acute or progressive weight loss may also happen due to adverse health conditions, such as cancer. If you suspect your child is losing weight for no apparent reason, consult a pediatrician (9).

Signs And Symptoms Of Abnormal Weight Loss

Dehydration is a sign of abnormal weight loss

Image: Shutterstock

Temporary weight fluctuations in children are a common phenomenon. However, they can become a matter of concern when accompanied by additional symptoms, such as (10):

  • General weakness and lethargy
  • Excessive sleepiness or insomnia
  • Loss of appetite
  • Vomiting, diarrhea, or constipation
  • Dehydration and decreased urination
  • Cough and sore throat
  • Abdominal discomfort
  • Fever
  • Dizziness and fainting
protip_icon Quick fact
Ear pain, chest pain, stunted growth, menstrual abnormalities, and feeling cold are some more symptoms of abnormal weight loss in children (17).

Diagnosis Of Unexplained Weight Loss In Children

Ascertaining the precise cause could help treat and manage weight loss in children. Your child’s pediatrician could recommend the following steps (11) (12). 

  1. Physical examination: The doctor will check for physical signs and symptoms of a possible underlying problem. Parents could be asked about the medical and dietary history of the child. The doctor will calculate the child’s body mass index (BMI) and plot it against standard charts, such as CDC’s growth charts. If the child’s body weight falls in the lower than the 5th percentile range, they are considered underweight.

    The doctor will calculate the child’s BMI to check whether they are underweight

    Image: IStock

  2. Diagnostic tests: The doctor may recommend blood tests, X-rays, and other scans, to determine deficiencies in nutrition and the cause of unintentional weight loss.

The doctor may suggest additional tests based on the results of the preliminary tests. If the child is diagnosed with a health condition, they may be referred to a specialist for further assessment and treatment.

Treatment And Management Of Weight Loss In Children

The treatment and management of weight loss will depend on the cause of the condition. Common illnesses, such as flu, causing weight loss can be treated by the primary healthcare provider. Chronic and complex health conditions, such as inflammatory bowel disease, genetic disorders, and hormonal problems, could require long-term care under the supervision of a specialist.

Children with eating disorders and substance addiction may require psychiatric help and other therapies to improve eating habits and lifestyle choices. Treatment or adequate management of the underlying cause usually stops weight loss and lets the child regain lost weight through appropriate dietary supplementation.

protip_icon Be watchful
Take a doctor’s opinion if you notice your child losing a lot of weight rapidly, not eating enough, skipping meals, complaining of feeling cold all the time, increased irritability and anger, or irregular menstruation (16).

Potential Complication Of Unintentional Weight Loss

Bone weakness is a complication of weight loss in children

Image: IStock

Unattended long-term weight loss in children may increase the risk of problems such as chronic fatigue, anemia, and muscle and bone weakness. Depending on the underlying cause and extent of weight loss, the child could also experience nutritional deficiencies. The child may also face psychological issues, such as poor concentration and poor self-image. In extreme cases, it may even lead to developmental delays and regressions.

Frequently Asked Questions

1. Is it normal for a child to lose weight?

Weight loss is normal when overweight children lose weight under a doctor’s guidance. Else, you should contact your child’s doctor to know the exact reason for weight loss. Children usually lose weight when they do not get enough calories or use more calories due to illness (10).

2. How much weight loss is normal in kids?

When following a childhood weight-management program, the child should not lose more than one or two pounds per week when supplemented with a healthy diet. Teenagers may achieve this goal by cutting down 500 calories a day, and those reaching puberty may cut down by 250 calories. This will ensure they healthily lose weight without affecting their growth (13).

3. What cancers cause unexplained weight loss in children?

Most childhood cancers might cause weight loss. LeukemiaiA cancer of the blood, lymphatic system, and bone marrow. , lymphomaiA cancer of the lymphatic system, the system responsible for the body’s immunity , nasopharyngeal carcinomaiA cancer of the area behind the nose and above the back of the throat , neuroblastomaiCancer that grows from multiple immature nerve cells , and central nervous system tumors are some of the common cancers (14).

4. Do children lose weight in a growth spurt?

Although most children may gain weight when experiencing a growth spurt, rapid growth in children may aid in reducing the obesity tag due to increased height and leanness in the tissue mass.

5. What is considered rapid weight loss in kids?

A rapid weight loss could be stressful and physically demanding for a child. Though occasional and planned weight loss is normal, rapid and excessive weight loss within a short period, accompanied by other issues, should be evaluated promptly in children (15).

6. What foods help a child gain weight?

Hannah Whittaker, an England-based pediatric and pregnancy dietitian, says, “If there are concerns with a child’s weight and it is not following the correct centile line, then I would advise parents on fortifying their child’s diet. Some examples of food fortification are adding high-energy foods such as butter, cheese, and cream to meals. I would also advise including nut butter and higher energy-dense foods such as avocado and oily fish to the diet.”

7. Can COPD cause weight loss in children?

Yes, chronic obstructive pulmonary disease (COPD) in children might cause weight drop, especially in severe cases like emphyse­ma, resulting in poor nutrition and low weight. This syndrome impacts muscle­s, essential for breathing and promotes muscle loss. Eating foods high in fat and prote­in helps keep a healthy weight. Yet, speaking to a doctor or dietician ensures safe fat consumption. Adding high-energy snacks with eggs, che­ese, and avocados helps fight COPD-related weight loss (16).

Gradual or slight weight loss in kids is common as they are in the growing stage, and different factors such as puberty, physical activity, or school stress can influence it. It can be managed in most cases with lifestyle changes, such as healthy eating. But rapid and abnormal weight loss is what you should look out for since it can indicate an underlying condition that requires your attention and medical intervention. So stay mindful of your child and consult your pediatrician for timely diagnosis and treatment of such issues.

Key Pointers

  • Poor eating habits, short-term illnesses, stressful events, or eating disorders are common causes of unintentional weight loss in children.
  • Loss of appetite, diarrhea, lack of energy, and fainting can often be associated with unintentional weight loss.
  • It is important to diagnose and treat unintentional weight loss in children to avoid complications such as anemia, bone weakness, and growth regressions.
Weight Loss In Kids_illustration

Image: Dall·E/MomJunction Design Team


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.

1. Common Causes of Unintentional Weight Loss; Family Medical Centers
2. Moritz Herle et al.; Emotional over- and under-eating in early childhood are learned not inherited; NCBI
3. Feeding and Swallowing Problems (Dysphagia); Cincinnati Children’s
4. Niemann-Pick Disease Information Page; NIH
5. Cystic Fibrosis & Nutrition; GI KIDS & NASPGHAN
6. Pediatric Crohn’s Disease; Yale Medicine
7. Drugs That Affect Body Weight, Body Fat Distribution, and Metabolism; NCBI
8. Substance use recovery and diet; U.S National Library Of Medicine
9. Weight Loss.American Academy of Pediatrics
10. Unexplained Weight Loss in Children and Teens; Harvard Health Publishing
11. Defining Childhood Obesity; CDC
12. About Child & Teen BMI; CDC
13. Unexplained Weight Loss in Children and Teens; Harvard Health Publishing
14. Pediatric Medical Nutrition Therapy Protocol for Weight Management; Pitt County Pediatric Dietitians and Nutrition Educators
15. Signs and Symptoms of Childhood Cancer: A Guide for Early Recognition; American Family Physician
16. Weight Loss in Children Can Be a Danger Signal; Rady Children’s Hospital–San Diego.
17. Pediatric and Adolescent Abnormal Weight Loss; Children’s Health

Was this article helpful?
Like buttonDislike button
The following two tabs change content below.
Dr. Aarti Motiani is a child specialist with a decade of experience in patient care.  She has special interest in nutrition, immunization, and development of kids. Dr. Motiani treats kids with minimal medicine and believes in parents counselling for every behavior of the child.read full bio