Published on: 2025-06-18 | Written by: Dr. Shimaa Hakim, specialist in therapeutic nutrition, public health, and non-surgical body sculpting
Severe thinness is a health issue that negatively impacts energy, immunity, and overall appearance. It may indicate underlying diseases or nutritional deficiencies. In this article, Dr. Shaimaa El-Hakim, Clinical Nutrition and Public Health Specialist, explains the main causes of underweight conditions and how to manage them through a comprehensive medical nutrition plan to achieve a healthy and safe weight.
A person is considered severely underweight when their Body Mass Index (BMI) is less than 18.5. This condition may result from medical, psychological, or dietary factors.
According to Dr. Shaimaa El-Hakim, the causes may include:
Medical conditions: Such as hyperthyroidism, malabsorption syndromes, type 1 diabetes, or chronic illnesses.
Psychological causes: Including anorexia nervosa or chronic stress.
Poor dietary habits: Like skipping meals or not consuming enough calories or protein.
High metabolic rate: Some people naturally have a faster metabolism.
Factor | Normal Thinness | Medical Thinness |
---|---|---|
Appetite | Good | Poor or absent |
General energy | Normal | Fatigue and sluggishness |
Immune effect | Minimal | Weakened immunity |
Weight loss | Slow | Rapid and unexplained |
Dr. Shaimaa El-Hakim states that diagnosis includes:
BMI measurement
Comprehensive blood tests to detect deficiencies or illnesses
Assessment of dietary habits and lifestyle
Treatment involves more than just increasing calorie intake. As Dr. Shaimaa El-Hakim explains, it includes:
Eating 5–6 meals daily
Focus on nutrient-dense foods like nuts, healthy oils, full-fat dairy, meats, and avocados
Protein or vitamin supplements as needed under supervision
Managing hormonal or digestive disorders
Providing psychological support in cases of anorexia
To boost appetite and build healthy muscle mass
Dr. Shaimaa El-Hakim recommends consulting a nutritionist if:
You experience rapid and unexplained weight loss
You suffer from chronic appetite loss
You show signs of nutritional deficiencies such as hair loss or weakened immunity
You want to gain weight in a healthy and safe way