Possible explanations

1. Energy and protein intake is too low for workload
   • Heavy physical labor and prolonged standing can produce a large daily energy expenditure.
   • Inadequate calories, protein, sleep, or recovery can lead to low muscle mass and may increase susceptibility to common infections.
   • Food insecurity, poor appetite, alcohol/substance use, depression/anxiety, and poor sleep should also be considered.
2. Recurrent tonsillitis may be a local ENT problem
   • Enlarged or chronically infected tonsils, exposure to children/crowding, smoking or tobacco, poor dental hygiene, allergic rhinitis/postnasal drip, or reflux can predispose to throat symptoms.
   • Each episode should ideally be confirmed with examination and, when appropriate, a rapid strep test or throat culture. Not every sore throat is bacterial.
3. Chronic infection
   • Depending on location, exposure, and symptoms, screening for HIV and tuberculosis is important. TB can cause low weight, fatigue, fever, night sweats, cough, or swollen lymph nodes, but may sometimes be less obvious.
   • Chronic hepatitis, intestinal parasites, and other infections may be relevant based on travel, sanitation, diarrhea, or exposures. Textbook discussions of unexplained weight loss specifically include HIV, TB, parasitic infections, and chronic inflammatory disease in the differential. Yamada's Textbook of Gastroenterology, 7th ed.
4. Malabsorption or gastrointestinal disease
   • Celiac disease, inflammatory bowel disease, chronic diarrhea, pancreatic disease, and parasites can reduce nutrient absorption.
   • Celiac disease may cause weight loss and malabsorption, but some people have few or no bowel symptoms. Yamada's Textbook of Gastroenterology, 7th ed.
5. Diabetes or other endocrine/metabolic disease
   • Diabetes can cause weight loss despite normal or increased appetite, especially with thirst and frequent urination.
   • Less common possibilities include adrenal disease and chronic kidney or liver disease.
6. Immune deficiency
   • This is not the most likely explanation for every thin person with colds, but it must be considered if bacterial infections are frequent, unusually severe, prolonged, involve pneumonia/sinusitis, need repeated antibiotics, or are difficult to clear.
   • Adult antibody deficiencies can first become apparent in adult life. The AAAAI recurrent-infection guidance flags more than two antibiotic-treated infections per year in adults as a reason to consider evaluation.

Useful next tests to discuss with a physician

• Weight history and diet review, including appetite, calorie/protein intake, sleep, alcohol/tobacco/substances
• Complete examination, including lymph nodes, oral/dental exam, tonsils, chest, abdomen, skin, and testicular examination
• CBC with differential and peripheral smear
• ESR/CRP
• Kidney, liver, electrolytes, albumin/total protein
• Fasting glucose or HbA1c
• Urine routine and urine protein
• HIV 1/2 antigen-antibody test
• TB evaluation if there are symptoms, exposure, or local risk
• Celiac screen: tTG-IgA plus total IgA
• Stool testing if diarrhea, abdominal symptoms, or parasite exposure
• If infections are documented/recurrent: serum immunoglobulins IgG, IgA, IgM, possibly vaccine-antibody response and lymphocyte subsets through an immunologist

ENT review

Nutrition while evaluation is underway

• Aim for three meals plus 2-3 calorie-dense snacks daily.
• Add eggs, milk/curd, paneer, pulses/beans, chicken/fish, soy, nuts, peanut butter, oils/ghee, rice, potatoes, bananas.
• A reasonable protein target for a laborer trying to regain weight is often around 1.2-1.6 g/kg/day, about 62-83 g protein/day at 52 kg.
• Add calories gradually rather than relying only on supplements. A dietitian can make this practical and affordable.

Seek prompt care if any red flags occur