[5:88] Eat of that which Allah hath bestowed on you as food lawful and good, and keep your duty to Allah in Whom ye are believers
Muslims can eat meat and vegetables.
The restrictions are mostly related to the type of meat we can eat. We must eat food that is halal, i.e. slaughtered in an Islamic manner. We are allowed to eat animals such as cow, sheep, camel and chicken etc. Muslims can not eat pigs, carnivorous animals, reptiles, insects, animals that were already dead and halal animals that were not slaughtered in Islamic fashion.
[16:5] And He created the cattle for you; you have in them warm clothing and (many) advantages, and of them do you eat.[2:173] He hath only forbidden you dead meat, and blood, and the flesh of swine, and that on which any other name hath been invoked besides that of Allah. But if one is forced by necessity, without wilful disobedience, nor transgressing due limits,- then is he guiltless. For Allah is Oft-forgiving Most Merciful
In terms of eating fish, since they die once out of water, we do not have to worry about it being salughtered in a halal manner, but are only allowed to eat fish that has scales on it.
Muslmis can also eat, plants which are not intoxicant, vegetables, fruits, grain foods; such as wheat and rice.