Pediatric and Adolescent Abnormal Weight Loss

If weight loss is caused by a medical condition or is a side effect of a medication, the symptoms will vary and be specific to that cause. Other symptoms can include:

• Constipation 
• Change in menstruation (period) or no menstruation
• Dehydration 
• Dizziness and fainting
• Fatigue (extreme tiredness)
• Feeling cold or low body temperature
• Low blood pressure
• Malnutrition or protein-calorie malnutrition 
• Stunted growth
• Weakness

Abnormal weight loss can occur due to several medical conditions, side effects of medication, or physical and lifestyle changes.

Medical conditions

• Addison’s disease (adrenal insufficiency) – This condition causes insufficient secretion of hormones from the adrenal cortex, which can cause weight loss.
• Cancer – A common symptom of cancer is weight loss, since fighting the cancer uses much of the body’s energy and it can change the way the body processes food and nutrition.
• Celiac disease – This condition causes the small intestine to be sensitive to gluten. This results in difficulty processing and digesting food.
• Chronic obstructive pulmonary disease (COPD) – Advanced COPD can cause weight loss as the damaged lungs increase in size, pushing against the stomach and making it difficult to eat.
• Crohn’s disease – This condition causes chronic inflammation of the intestines, which leads to nausea, abdominal pain and a loss of appetite.
• Depression – Children with depression can lose weight due to a decreased appetite.
• Diabetes – Insufficient insulin is the root cause of diabetes. This can lead to the body burning fat and muscle for energy to make up for the loss of glucose.
• Eating disorders – Young children and teens sometimes try to control their weight and develop eating disorders like anorexia and bulimia.
• Heart failure – Many heart failure patients live with unintentional weight loss. While the exact cause is unknown, recent studies have found reduced blood flow and the resulting nausea may be a possible reason.
• HIV/AIDS – Many patients with HIV/AIDS experience weight loss for a number of reasons, such as an infection, depression, or pain in the mouth from sores or a yeast infection.
• Hypercalcemia – This condition causes increased levels of calcium in the blood, which can lead to a decreased appetite and abdominal pain.
• Hyperthyroidism – With this condition, the thyroid gland produces too much of the thyroid hormone. This can impacts a child’s metabolism and lead to weight loss. 
• Parasites – A parasitic infection can lead to weight loss due to chronic digestive issues, autoimmune disorders or protein-calorie malnutrition.
• Parkinson’s disease – This condition is a progressive disorder of the nervous system. While the exact cause is unknown, some theories cite the loss of smell, the energy required during tremors or gastrointestinal issues as reasons for weight loss.
• Peptic ulcer – This is a sore that forms in the lining of the digestive system, which can make eating painful and result in weight loss.
• Sensory processing disorder – Children with sensory disorders may be particularly sensitive to the feel, smell or taste of foods or drinks, including during breastfeeding.
• Ulcerative colitis – This inflammatory bowel disease causes painful sores and inflammation of the digestive tract, making it difficult to eat and process food.

Side effects of medications

• Anti-anxiety drugs – These medications target hormones and chemicals in the brain, and can cause decreased appetite and unintentional weight loss.
• Antibiotics – These medications eliminate disease-causing bacteria and can cause short-term effects on the gastrointestinal tract.
• Anti-cancer drugs – Weight loss is common when treating cancer since chemotherapy or radiation therapy often result in appetite loss, nausea and vomiting.
• Cardiovascular drugs – Antiplatelet drugs, often used to treat coronary heart disease, can cause diarrhea and abdominal pain that leads to weight loss.
• Stimulants – Some stimulants, such as phentermine and topiramate (an anti-seizure and migraine medication), can cause decreased appetite and weight loss.

Physical and lifestyle changes

• Activity levels – One of the largest contributors to a weight imbalance is a drastic increase in activity levels while there is a decrease in food consumption. Overall health requires a balanced diet and activity level.
• Dental issues – Pain from dental issues or improper brushing techniques can lead to decreased appetite or temperature sensitivities.
• Gut health – The human body needs the appropriate balance of microbes in the stomach (gut flora) in order to properly function and maintain a healthy weight.
• Puberty – Increased hormones in a child’s body during puberty (between the ages of 10 and 14 for girls and between the ages of 12 and 16 for boys) leads to growth and dramatic slimming of “baby fat” areas.
• Substance abuse – Abuse of stimulants (cocaine or ecstasy), depressants (alcohol or marijuana) and narcotics (prescription medications) can lead to rapid, significant weight loss.