Central Obesity: Given the abdominal circumference of 29 inches, which is above the normal range for an Asian female (typically considered > 80 cm or approximately 31.5 inches for Asians, but can vary based on source), the single most likely diagnosis is central obesity. Central obesity is a key component of metabolic syndrome and is associated with increased risk of cardiovascular diseases, type 2 diabetes, and certain types of cancer. The justification for this diagnosis is based on the measurement itself, which directly correlates with increased visceral fat.

Metabolic Syndrome: This condition is characterized by a cluster of factors including central obesity, hypertension, dyslipidemia, and insulin resistance. Given the central obesity indicated by the abdominal circumference, metabolic syndrome is a likely consideration.
Polycystic Ovary Syndrome (PCOS): While not exclusively defined by abdominal circumference, PCOS is often associated with central obesity, insulin resistance, and other metabolic disturbances. It's a common endocrine disorder in women of reproductive age and could be considered in the differential diagnosis.
Hypothyroidism: Sometimes associated with weight gain and potentially increased abdominal girth, hypothyroidism could be a contributing factor, although it would not be the first consideration based solely on abdominal circumference.

Cushing's Syndrome: A rare endocrine disorder caused by excess cortisol, which can lead to significant central obesity among other symptoms. It's crucial not to miss this diagnosis due to its potential for serious health consequences if left untreated.
Intra-Abdominal Tumor or Mass: Although less likely, an intra-abdominal tumor or other mass could contribute to an increased abdominal circumference. Missing such a diagnosis could have severe consequences, making it a "do not miss" consideration.
Ascites: The accumulation of fluid in the peritoneal cavity, often associated with liver disease, heart failure, or other serious conditions. Ascites can significantly increase abdominal girth and is a critical diagnosis not to overlook.

Prader-Willi Syndrome: A rare genetic disorder that can cause excessive hunger and eating, leading to obesity. While rare, it's an important consideration in individuals with significant obesity, especially if other characteristic features are present.
Lipodystrophy: A group of rare disorders characterized by the selective loss of body fat. Some forms can present with central obesity due to the redistribution of fat.
Familial Partial Lipodystrophy: Similar to lipodystrophy, this is a rare genetic disorder affecting fat distribution, which can sometimes present with increased abdominal fat.