Voltaire said that the best (or the perfect) is the enemy of the good. And when it comes to diet, there is a definite risk that setting standards of perfection will paralyze us into inaction. On the flip side, it’s not great to let a few good choices make us so complacent that we don’t seek to do more.

A good example of this in the world of dietetics occurred when Americans got cholesterol savvy and started trading in beef for white meat such as chicken. That was a moderate improvement in eating habits that let people feel good about their diets—but by itself, it doesn’t make a diet “heart healthy.”

More recently, I’m seeing examples of this in regard to diet and environment. I live in a fairly progressive community of people who are, for the most part, sincerely committed to making choices for the greater good. Most are devoted to shopping and eating locally and choosing sustainable types of food. Our little farmers’ market is bustling in the summer and the food co-op is always crowded. Restaurants tout their sustainable menus with meat, dairy and produce from farms right here in our rural county.

Eating locally-produced food is good, of course. There are many excellent reasons to support community businesses and family farms. But the effects of those choices on the environment are marginal at best compared to the impact of eating a plant-based diet.

A study published last year in the journal Environmental Science and Technology found that reducing red meat and dairy consumption is far more effective than buying locally-produced food for reducing greenhouse gases. In fact, the researchers estimated that reducing consumption of these foods by just 11-19% was as effective as 100% local buying!

Do shop locally and buy organic when you can. But for real impact, nothing compares to eating a more plant-based diet.