One's model of reality should be complete. Calorie-in-calorie-out only captures a very small part of reality. 1. Humans are conscious beings, and deciding to c

One's model of reality should be complete. Calorie-in-calorie-out only captures a very small part of reality. 1. Humans are conscious beings, and deciding to change your weight is a conscious decision, and one that requires constant mental effort over months to achieve. 2. If you are trying to lose/gain weight, your body actively tries to sabotage you via releasing hormones that act like drugs for your brain to acquire food/stop eating. This happens every day, constantly for months on end, that you have to fight it 24/7. 3. Its well documented that humans have a finite amount of mental concentration/decision making per day after which the brain acts more and more on autopilot. Sure, you can increase this amount, but this requires its own training. 4. Humans have jobs and social obligations to family and friends, that consume much of the finite concentration. Every so often, you will mess up and eat too much/too little. 5. Sometimes, those around you will actively sabotage your efforts. 6. Every failure can be a power emotional demotivator, which makes it harder to stick to your goal. So, no, the amount of real world control that a human exerts on their eating habits is far less than 100%.