There’s a lot more to energy balance than a change in body weight.
Energy balance also has to do with what’s going on in your cells. When you’re in a positive energy balance (more in than out) and when you’re in a negative energy balance (more out than in), everything from your metabolism, to your hormonal balance, to your mood is impacted.
The relationship between the amount of Calories we eat in the diet and the amount of energy we use in the body determines our body weight and overall health.
The body is highly adaptable to a variety of energy intakes/outputs. It must be adaptable in order to survive. Therefore, mechanisms are in place to ensure stable energy transfer regardless of whether energy imbalances exist.