A calorie measures the heat released by setting the food on fire, which is not how your body metabolizes food. It's a proxy. You should be measuring the ATP yielded by eating food. For example, a molecule of glucose yields 32 ATP when metabolized, yet a molecule of DHA yields 136 molecules of ATP - nearly twice as many as predicted by the "calories" proxy. However, in the absence of oxaloacetic acid (as when the liver is using the majority of OAA for gluconeogenesis during intense exercise or when limiting carbohydrate consumption) your cells have to use a less efficient series of metabolic steps to produce energy and only end up yielding 22 ATP for DHA metabolism. I eat 3500 calories a day and don't exercise yet I'm losing about 2 pounds of fat per week.

CICO was never law.