Your troops have an upkeep, meaning they eat your food. The more troops you have the more food they consume and also the higher the tier or level of your troops, the more food they consume. This guide will explain how to maximize your food production and how to reduce your upkeep.
As a beginning player you should understand you do not need to keep feeding your troops. Nothing bad happens when you have zero food left. Do not gather or open food items just to feed your troops, there is no benefit.
So your troops don't die when you have zero food, but it is still annoying. You cannot save up food for doing big training sessions, researches or buildings, because it just gets eaten and you practically need food for anything, so you always have to plan carefully when you need food.
In my eyes it is important to train a very large army, and don't worry about keeping your upkeep smaller than your food production, just learn to deal with it.
You might be tempted to solve the issue by increasing your food production. Build many farms, wear hero equipment that boosts food production, do all the research and assign skill points to boost Food production as well. Not necessarily a bad idea and in the beginning it is helpful, as you are still doing many buildings, training and research projects in a short time, and being zero on food is annoying, but just increasing your Food production will likely not help you in the long run, assuming you will build a huge army.
Building and upgrading farms increases your basic food production. Note that when your farms reach level 15 you can chose between the standard (or T1) food or T2 food, the T2 food is used for upkeep of higher tier troops.
In the Economics research category you have projects increasing the standard Food, T2 Food, and total Farm Production.
In the Hero Skill tree there is also a project increasing your Farm Production.
VIP 1 increases your Food Production with 100%. I don't have data on higher VIP levels yet, but assume T2 Food production can also be increased.
The Folding Shovel accessory provices a Food Production increase.
The only way I know of to increase Upkeep Reduction, is the Upkeep Efficiency (T1) and (T2) project in the Hero Skill tree. Perhaps later more ways will be introduced. There are similar games that later on added ways to reduce the upkeep reduction to 0.
Just a side note, compared to some other games the upkeep seems actually quite low in World War Rising.
Focus on saving food in Food items. Be selective when you use these, if you can get your food in other ways this might be better, so that you wait with using items until you really need it. Plan ahead by for example sending tree marches out to gather food if you expect to require some food soon.
Consider as an alliance to have one zero upkeep account, if not having one for personal use. This is only useful in relative peaceful kingdoms, otherwise it becomes a target for other alliance. Here people can move their excess food to and collect it when needed.
Also consider making a few farm accounts. A farm acccount is basically just an extra account that has as sole focus to provide resources (via production, potentially also via gathering) for your main.
You can also consider to let each player in your alliance hyperfarm one resource. Hyperfarming means each player focuses their complete production to one resource, and provides that resource for other players in the alliance that need it, and in return that player will get all other resources he requires from the other players. This requires a good collaboration and a lot of trust.
Keep training troops, keep your food production high, and don't worry too much when you reach the point that your upkeep becomes larger than your food production.