Do I have to eat the full amount of calories per day? 

Yes. 

It’s highly recommended that you don’t use hunger as your guide, often dieters can experience little to no hunger while on HCG and following the meal plan. 

This means that if you are not hungry, yet fail to consume the minimum daily caloric intake you may experience low weight loss numbers, stalls in weight loss and/or fatigue. 

Less food does not produce faster weight loss. You must consume the precise micronutrient daily to ensure maximum fat loss.