Do not worry; there are many factors that affect your balance of resources, like:

- Your base being attacked, and your resources are looted; and to protect these resources, upgrade your resources store to increase the capacity of the protected resources.
- Using resources in upgrading and building.
- Using resources for alliance donations.
- Using resources to control the general's skills.
- Using resources to purchase from the black market.
- Using resources to complete research.
- Using resources to heal damaged units in the workshops.
And many other things ...

Note: Units have the cost of living, they consume food, and you to know the total food use by your units, click on your strength balance, and you will find this information at the top of the screen (Number of units - Total marching troops - Total food use - Damaged units).