The exact diet of wild hamsters is not completely known, however they are naturally omnivorous so will eat a wide range of things (e.g. seeds, fruits and insects).
There are many different dried hamster foods available on the market. These provide all the vitamins and minerals that your pet needs to stay healthy. Hamsters will only eat what they need to and rarely become overweight, but it is possible to waste a lot of food by overfeeding them. Hamsters store their food in a specific area of their cage and transport it from the food bowl to their store in their large cheek pouches. This means that the food bowl always looks empty. Do not be fooled into thinking your hamster must be hungry - he has a nice stash of food hidden somewhere! In fact, scattering a small amount of food around the cage is much better than putting it into a bowl. It allows the hamster to perform natural foraging behaviour and reduces the tendency to keep a bowl filled up.
Hamsters also like to have some fresh foods every now and then but do not overdo it. Bits of apple, carrots and sweetcorn are fine, but only give a little bit at a time and try to avoid foods with a large percentage of water. Feeding too much lettuce, etc. can cause severe stomach upsets which at worst may kill your hamster! Check your hamster's feed store regularly when feeding fresh foods to ensure that they do not start rotting.
You can use small amounts of a favourite food as training treats. Hamsters love sunflower seeds, peanuts and sultanas. By hand-feeding them some treats, you will help them to become acustomed to you and this will help with taming. Do not overdo this, however, as sunflower seeds are very high in fat.
Ensure fresh water is always freely available using a water bottle fixed to the outside of the cage.