A 52-year-old man from rural Maharashtra presents to a health camp with a chief complaint of increased thirst and frequent urination for the past 3 months. He works as a farmer and has a sedentary lifestyle during off-season. His father had diabetes diagnosed at age 58. On examination: BMI 28.5 kg/m², blood pressure 138/88 mmHg. Fasting blood glucose 156 mg/dL, HbA1c 8.2%. He denies any acute symptoms. Based on current epidemiological trends in India, which of the following is the MOST significant modifiable risk factor contributing to his diabetes risk in the Indian context?