To reach a healthier weight this summer, consider throwing some portobello mushrooms, veggie burgers and fish on the grill in place of steak, hot dogs and chicken.

A new study of some 55,000 healthy, middle-aged Swedish women finds that those who ate little or no meat weighed significantly less than their more carnivorous counterparts. The findings are some of the first to show a direct link between a plant-based diet and a lower body mass index, or BMI.

This doesn't mean that you have to forgo juicy steak and other animal-derived foods all the time. The study found that while lacto-vegetarians -- who ate dairy products but avoided meat, poultry, fish and eggs -- had the lowest BMI, those following a somewhat less limited diet also scored better than the meat-eaters. "The take-home message is that individuals who have the lowest risk of being overweight or obese are consuming a mostly plant-based diet." said P.K. Newby, lead author of the study and a scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston.

Numerous studies have demonstrated health benefits of eating a diet rich in plant-based foods, from fostering healthier blood pressure levels and reduced blood cholesterol to a lower risk of heart disease, diabetes and certain types of cancer.

The latest findings are drawn from healthy women in a large mammography trial conducted by the Karolinska Institute in Stockholm. Participants answered questionnaires and submitted food records in 1987 and then again in 1997. As the authors note, such cross-sectional studies have limitations, so the findings will need to be confirmed by more rigorous trials.

The study found that 40 percent of women who ate meat, poultry, fish, eggs and dairy products as well as plant-based foods were overweight or obese, as defined by having a body mass index of 25 or more. (That's equal to a person 5 feet 6 weighing 155 pounds or more.) Compare that to 29 percent of the self-described vegans, who ate no animal products, and semi-vegetarians, defined as skipping meat, poultry and eggs but eating dairy products and fish. The leanest women were the lacto-vegetarians: 25 percent of this group were overweight or obese.

One surprise for the research team was that all the participants who considered themselves vegetarians or vegans reported on food records that they ate some animal products from time to time.

Meat-eaters took in the most calories, consumed the highest amount of protein and the most saturated and mono-unsaturated fat and "had significantly lower carbohydrate intake than did any of the three vegetarian groups," the researchers report in the American Journal of Clinical Nutrition. The authors note that the results are likely "generalizable to younger women and to men."

Even so, Newby and other nutrition experts note that not all vegetarian foods are healthy. A steady intake of sweetened soft drinks, french fries and candy bars qualifies as vegetarian, but is loaded with saturated fat, unhealthy trans fat and added sugar. Plus, it's high in calories and lacks fiber and many essential nutrients.

Here are a few simple ways to add plant-based foods to your daily fare and to make smart choices about animal foods:

Go semi-vegetarian sometimes. You may be doing it already. Breakfast on shredded wheat with berries, slivered almonds and skim milk. Have a large Greek salad with feta cheese and a crusty bread for lunch. Snack on fruit and yogurt and eat a couple of bean burritos with a little low-fat cheese and some rice for dinner. Have fruit for dessert and you've had a semi-vegetarian day.

Try some meatless options. Gazpacho, pasta with pesto or tomato sauce, bean soup, vegetable lasagna, hummus, a peanut butter-and-jelly sandwich on whole wheat, a stir-fry with tofu or a grilled cheese sandwich(with reduced fat mozzarella) are some tasty options. Plus, there is a growing number of meat substitutes, from Boca burgers and "chicken" nuggets to Smart Dogs (made with soy), textured vegetable protein and meatless breakfast links.

Choose the leanest cuts of meat and poultry. Meat-eaters in the study consumed about 30 percent of their daily calories as fat, nearly half of it from saturated fat. Fat intake for the vegetarian groups, which ranged from 23 to 26 percent of total calories, contained 11 to 13 percent saturated fat, both close to the 10 percent limit recommended by the U.S. Dietary Guidelines. Trim unhealthy fat by consuming flank steak instead of porterhouse, skinless chicken or turkey breasts instead of fattier wings or dark meat and very lean hamburger in place of ribs. Marinades and low-fat sauces can boost flavor without adding unhealthy fat or huge amounts of calories.

Have healthy carbs. All three vegetarian groups ate two servings daily of whole grains, about a serving of cereal, two servings of fruit and nearly three servings of non-starchy vegetables. They had nearly a serving per day of potatoes and ate the least amount of refined grain foods, which are low in fiber. These results and others "suggest that a high-carbohydrate diet may be protective against obesity if the carbohydrates come from fiber-rich foods, such as fruit, vegetables and whole grains," USDA researcher Newby said. High-fiber choices include berries, especially blackberries and raspberries; beans and legumes; broccoli and leafy green vegetables; whole-grain bread, pasta, unsweetened cereal and crackers.

Use some dairy products. Just make them nonfat or 1 percent fat. All three vegetarian groups reported eating dairy products, even the vegans, who had about two servings daily. But lacto-vegetarians, who had the least rates of overweight (21 percent) and obesity (4 percent), reported consuming four servings daily of dairy products -- one more than the three daily recommended by the U.S. Dietary Guidelines.


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