Even if you don't want to serve a meal, make sure your guests have snacks to nibble on. If they are hungry and there is no food available, they are more likely to drink to curb their appetites, and digesting food slows down the absorption of alcohol. If you are serving a meal, serve your guests an appetizer or put out some freshly baked bread before serving any alcohol.
Choose the food you serve wisely. Your two goals in selecting foods are to slow down alcohol absorption, and to slow down the rate at which your guests are drinking. Foods that are relatively high in fat, such as pate, creamy dips, cheese and crackers, will slow down the absorption of alcohol more than lower fat snacks such as fruit, which, despite their good health record, won't do as good a job on their own. But as fruit contains more water than many foods, it will help to prevent your guest from getting thirsty. You should take particular care to avoid salty foods, such as salted potato chips and salted nuts, which will make your guests thirsty and more likely to drink quickly, one reason they are always available in bars and pubs. Unsalted chips or nuts are fine, particularly when combined with fruit or a low sodium dip, such as guacamole (hold the salt) to offset the dryness.