Step 1: Understanding the Concept:
Weight gain occurs when the energy intake (calories consumed) exceeds energy expenditure (physical activity).
Step 2: Detailed Explanation:
- Excessive calories: High intake of energy-dense foods.
- Sedentary lifestyle: Lack of physical movement or exercise.
When these two factors combine, the body stores the excess energy as fat, leading to Obesity. While obesity can contribute to Hypertension and Back Pain, it is the direct primary result of this combination.
Step 3: Final Answer:
The primary cause of Obesity is high calorie intake and a sedentary lifestyle.