German staple diet

What kind of food do Germans eat - in Fruhstuck, mitagessen and abendessen to have a proper fit diet?

When i language books there are examples of gemuse, suppe, apfel, kartoffel and brot a lot. I dotb suppose one can have a full stomach on those ??

What kind of food would you eat to fill your stomach and have it meet the BMI standard? (From amongst what is available in germany). What do you cook or eat at home that keeps you rocking.