The inside of a multi-layered onion gives you intense flavor, crisp texture, and a surprising number of health and weight-loss benefits. Although you might be most familiar with the yellow onion, the National Garden Association indicates that growers group onions into the sweet or pungent category. In general, the smaller the onion, the more pungent its aroma and flavor, and the larger the onion, the more sweet its flavor becomes.
Onions are naturally low in calories, with a medium-size onion giving you just 44 calories. A single cup of chopped onions contains 64 calories, and a single slice of onion that you might put on top of a veggie burger has 6 calories. A cup of spring onions, or scallions, and their tops contain just 32 calories. Adding onions to your diet will not cause weight loss, but substituting onions for higher-calorie foods can help you reduce your calorie intake.
In spite of its relatively small size, the onion gives you several important nutrients. A cup of scallions has 2.6 g of fiber, and 1 cup of white or yellow onions contains 2.7 g of fiber. Adequate intake of fiber aids in weight loss, as evidenced in a review study published in the March 2005 issue of the journal "Nutrition." Women and men between 19 and 50 years old need between 28 and 34 g of fiber, and females and males over 51 need between 22 and 28 g. Other beneficial nutrients in onions include 25 mg of calcium, 8.1 mg of vitamin C, a trace of B vitamins and just 4 mg of sodium. The National Onion Association indicates that onions have chemicals called organosulfur compounds that might help both your cholesterol and blood pressure.
Although onions do not contain the same metabolism-properties as red peppers, the intense flavors of onions can help you spice up your foods with little calories. Instead of seasoning your vegetables with bacon fat and salt, season them with a combination of fresh or lightly sauteed onions and garlic. Add onions to your salads instead of fried Italian croutons, and top a low-fat pizza with onions instead of meat. Every calorie you save can help you create the 3,500-calorie deficit you need to lose weight.
While onions are a healthy part of your diet, and might help you lose weight, remember that the healthiest way to lose weight is to eat the right mix of foods to give you the nutrients you need. The 2010 Dietary Guidelines indicates that onions fall into the "other" vegetable category, and you need 2 1/2 to 3 1/2 cups of vegetables from this category each week in addition to vegetables from the green, red, orange, starchy and beans or peas category. Eat grains, proteins, healthy oils, fruits and reduced-calorie dairy products, along with the onions you include in your diet.
- National Garden Association: Onion Varieties
- USDA Nutrient Data Laboratory: Onions, Scallions
- “Nutrition”; "Dietary Fiber and Body Weight"; Joanne Slavin; March 2005
- National Onion Association: Cooking with Onions
- Centers for Disease Control and Prevention: Balancing Calories
- U.S. Department of Health and Human Services: Dietary Guidelines for Americans 2010