What factor can contribute to obesity in individuals?

The factor that contributes to obesity in individuals is a lack of exercise. Regular physical activity is vital for maintaining a healthy weight because it helps to burn calories and build muscle, which can increase metabolic rate. When individuals do not engage in enough physical activity, they may consume more calories than they burn, leading to weight gain over time.

In contrast, eating healthy food, which likely refers to a balanced diet rich in nutrients, is generally associated with maintaining a healthy weight rather than contributing to obesity. Natural metabolism is also a factor in weight management, but it is not a primary contributor to obesity; instead, it varies from person to person and can influence how quickly or slowly one's body processes food. Frequent physical activity is crucial for weight control and is associated with preventing obesity rather than causing it.