"Flexitarian" is a relatively new term used to describe a diet that focuses on vegetarian foods but occasionally includes some meat. A book, The Flexitarian Diet by Dawn Jackson Blatner, R.D., published in 2008, popularized this idea and promotes a gradual transition from a meat-based diet to one that is mostly vegetarian with only two meals per week including animal foods.
In some respects, the flexitarian approach is not very different from my Anti-Inflammatory Diet, which emphasizes vegetables, fruits, whole grains, beans and other legumes, and healthy fats. The Anti-Inflammatory Diet also encourages you to eat fish and seafood two to six times a week and other sources of animal protein, including lean meat, poultry and eggs less often, only once or twice a week at most. The Anti-Inflammatory Diet is designed to help counteract the chronic inflammation that is a root cause of many serious diseases, including those that become more frequent as we age. It is a way of selecting and preparing foods based on science that can help people achieve and maintain optimum health over their lifetime.
As you may know, I was a lacto-vegetarian (my diet allowed for some dairy products) from 1970 to about 1987, when I began to include eating fish, so I know from personal experience that a vegetarian diet can be both healthy and satisfying.
It is interesting to me that a lot of the current enthusiasm for vegetarian eating stems from increased awareness of the health benefits of this type of diet rather than a concern for animal rights, as was often the case in the past (and remains a very important issue for some). It is certainly easier to be a vegetarian these days than it used to be, with an abundance of products available: veggie burgers (which I understand you can now get at Burger King as well as from supermarket freezers) and soy- and wheat-based meat substitutes. Even with the occasional indulgence of a steak, becoming a flexitarian or a part-time vegetarian is better for your health than following the mainstream American diet.
If you decide on the flexitarian approach to eating, I would encourage you to make healthy choices when you do eat meat and to watch your portion sizes. (I suggest limiting your servings to 3 ounces.) You're better off eating beef from grass-fed cattle than that from animals raised on factory farms and fed grain (not to mention hormones and antibiotics). Meat from grass-fed cattle has more omega-3 fatty acids, vitamin E and conjugated linoleic acid - all good for human health. (Note: organic beef isn't necessarily grass-fed. The cows may be raised in pesticide-free pastures, but they are still taken to feedlots and fed grain prior to slaughter.)
If you eat chicken, choose organic, cage-free chicken. As far as fish is concerned, choose wild Alaskan salmon (especially sockeye), herring, sardines, and black cod (sablefish), all of which are rich in omega-3 fats.
Andrew Weil, M.D.