In Orthodox Church, fasting is very strict and important. We can eat only fruit, vegetables and sometimes fish. While cheese, milk, eggs and meat is forbidden. During the Great (Easter) lent, 7 weeks, fish is forbidden, it is allowed only during Palm Sunday. To receive Holy Communion one must fast 7 days, must confess and must not eat or drink anything after midnight before the Liturgy. When there is no lent period, one must fast Wednesday (Day Christ was betrayed) and Friday (Crucified). There is also “no oil” fast, you cant use oil, that means you cant bake anything, you can only use water to cook.
The canons are very strict, but Church is not able to enforce them. If one doesn’t fast on a fasting day, he cannot receive Holy Sacraments for one entire year. And if a cleric person doesn’t fast, he is to be dismissed from his high service.
Of course, for married People, sex is not allowed during fasting days. And People are asked to double their prayers and more.
There is also “bread and water fast”. People eat only bread and drink only water for 7 days. Mostly used only by monks, but also regular People are welcome.
Saint Nikolai Velimirovich said that People should not reject fasting, because it is good for our bodies and souls, and that is why Lord commanded it through His Church, it is for our good.