For consumers looking to reduce the size of their carbon footprint, an examination of the food they purchase seems like a logical place to begin. Aside from sleeping and working (for better or worse), what aspect of day-to-day existence owns a more prevalent role than eating?  Environmentalists have numerous suggestions about how to green our diets.  Just as nutritionists refer dieters to the Nutrition Facts label, environmentalists would like to guide food purchases based on a Carbon label placed on each product.  And much like traditional dieting fads, eco-dieting advice has changed dramatically in recent years, as the environmental efficiency of food becomes more accurately measured.

Nutritional axioms have frequently changed over the past few years.  In the beginning, calories were the sole adversary of a healthy diet.  Individuals were told to reduce caloric intake in order to shed unwanted pounds.  Then, fat became public enemy number one.  In a sudden reversal of course, the Atkins diet declared fat to be a misunderstood ally (think Poland) and carbohydrates to be the traitor in our midst.  The citizens of South Beach welcomed good carbohydrates back into the family while expelling what it deemed to be bad fats.

A similar evolution is occurring in the world of eco-dieting. 

Originally, consumers were told to purchase organic foods - those grown without the use of pesticides and artificial fertilizers.  Now, consumers are instructed to note the distance traveled by the item (food miles) to the point of sale.  But, these locavores might be disappointed to learn that only 2% of the environmental emissions associated with a product occur during transport, while 98% occur during production, packaging, storage, and consumption. 

For instance, a shopper in London would do a better service to the environment by purchasing New Zealand lamb rather than Scottish lamb because the low amount of energy needed to raise a lamb on New Zealand far outweighs the emissions that occur during its transport.  Furthermore, not all food miles are equal.  Food miles associated with ships are less harmful to the environment than those derived from a truck.   

New methods are being developed that measure the total energy efficiency of different foods.  Ultimately, environmentalists need to better measure the ecological impact of food if they want to influence consumer behavior.  Consumers have historically shown a willingness to make eco-friendly purchases if they’re provided straight forward information. Meanwhile, the haphazard approach of measuring food miles not only obfuscates the complexity of the issue, it leads to purchases that exacerbate the problem.