The main changes in habits and behaviours on food to have a more responsible consumption are:

• Eat local: Although not all goods are available locally, a surprising number are. Farmers markets and CSA (consumer-supported agriculture) organizations are sprouting up in historic numbers, making it simpler than ever to buy locally. This drastically reduces fossil-fuel usage, helps local farmers, and restores the feeling of community that has been completely lost in a world of McDonald's and Walmart.
• Eat organic: Organic agriculture, while not a panacea, avoids or limits the use of synthetic fertilizers and pesticides. This minimizes not only the number of poisons discharged into the environment (and our bodies), but also the amount of fossil fuel required to produce those compounds. Unfortunately, most of these savings might be lost if organic fruit is delivered large distances. When given the choice between local and organic, local is almost always preferable.
• Eat Less meat: While the majority of the world's population now follows a vegetarian or near-vegetarian diet, residents in developed countries consume large amounts of animal protein.