Obesity

Obesity is the accumulation of excess body fat to a degree that harms health. It is commonly assessed using body mass index (BMI) — weight relative to height — with 25–30 defined as overweight and 30 or above as obesity, though waist measurement adds useful information because fat carried around the abdomen is especially harmful. It arises from a complex interplay of diet, physical activity, genetics, environment, sleep, medications and hormonal and metabolic factors, and is not simply a matter of willpower. Its importance lies in its consequences: obesity is a leading driver of type 2 diabetes and insulin resistance, high blood pressure, abnormal cholesterol, fatty liver, heart disease and stroke, obstructive sleep apnea, osteoarthritis of weight-bearing joints, several cancers, and effects on fertility and mood. The encouraging counterpoint is that these risks are modifiable: even a 5–10% reduction in weight produces meaningful improvements in blood sugar, blood pressure and other measures. Blood tests do not diagnose obesity but map its metabolic consequences.

• HbA1c and fasting glucose — screen for the insulin resistance, prediabetes and type 2 diabetes that obesity drives.
• Lipid panel (triglycerides, HDL, LDL, non-HDL) — often shows high triglycerides and low HDL (the metabolic-syndrome pattern).
• Liver enzymes (ALT) — for non-alcoholic fatty liver disease, which commonly coexists.
• Blood pressure — frequently raised.
• TSH — to exclude an underactive thyroid as a contributor. The tests assess the metabolic impact and associated conditions, not obesity itself, which is measured by BMI and waist.

• Often no symptoms from the excess weight itself early on
• Breathlessness on exertion, reduced stamina
• Joint and back pain, especially knees and hips
• Snoring and daytime sleepiness (sleep apnea)
• Tiredness
• The symptoms of associated conditions — diabetes, high blood pressure, fatty liver
• Effects on mood, self-esteem and quality of life