Do low-carb diets work?

Low-carbohydrate foods are the latest craze, with increasingly more "low-carb" options available at restaurants and in grocery stores. But do low-carb diets actually work?

To fight the bulge, you must eat fewer calories than the amount of calories you use for daily activity. Any eating plan that helps you consume fewer total calories can help—including low-carb diets. The trick is to meet nutritional needs by choosing healthy foods. It’s important to be aware of certain risks that can be associated with a low-carb diet and to understand labeling terms.

Benefits. First of all, any diet that severely restricts choice can reduce calories through boredom. For example, eating bacon and steak and nothing else can result in fewer total calories because you’re bored with eating the same thing all the time. Eating plenty of colorful, "allowed" low-carb vegetables, such as broccoli, lettuce, bell peppers and spinach, will provide important vitamins, mineral, potassium, folic acid, fiber, and phytochemicals that are found naturally in healthy foods.

Risks. Even though many manufacturers are jumping on the low-carb bandwagon, consider these risks with high-protein, low-carb diets:

Labeling. Low-carb claims on nutrition labels are illegal because the Food and Drug Administration (FDA) has not defined the term "low-carb." The FDA prohibits any nutrient claim it has not defined. Most "low-carb" labels do not back up their claim (as the FDA requires for claims such as "reduced fat" and "low-calorie.")

In some cases, "low-carb" foods do NOT have fewer total carbohydrates, but only have what manufacturers refer to as fewer "net carbs." The use of the term "net carbs" by manufacturers is misleading. "Net carbs" is a figure found by subtracting grams of sugar alcohols and fiber from total carbohydrates. However, sugar alcohols do have calories, so the net carb value may not help you choose a healthier food. Without research showing health benefits, the FDA will not approve claims on labels.

Low-carb restaurant meals vary. Some meals with low-carb claims are actually lower in calories, but other meals have more calories. A 1000-calorie, low-carb lunch is still a 1000-calorie meal. The following low-carb restaurant meals all top 1000 calories: low-carb Buffalo wings, low-carb spring chicken salad, low-carb steak fajitas, and low-carb rib-eye.

To cut carbohydrates in low-carb breads, manufacturers replace sugar with artificial sweeteners like sucralose (Splenda) and wheat flour with extra fiber, soy protein, wheat gluten, or wheat protein. These products are often similar to regular 100 percent whole wheat breads. Check labels to compare similar products. Subtract fiber in the original bread from the carbohydrates on its label for a more accurate comparison.

Low-carb frozen desserts use sugar substitutes like sucralose (Splenda), cellulose gums, and sugar alcohols (mannitol, xylitol, sorbitol). Some of these products are also high in saturated fats.

Low-carb candies use sugar alcohols, but these are not low-calorie products. In addition, too much sugar alcohol can have a laxative effect.

Recommendations. A low-carb diet may lead to weight loss, but don’t expect as much as the diet books claim. If you choose a low-carb diet, try a healthier version based on a small portion of low-fat protein. Fill up with plenty of fruits and vegetables and smaller amounts of nuts and seeds. Healthy diets are rich in fruits and vegetables, beans, whole grains, seafood, poultry and low-fat dairy products, as well as some oils, nuts, and unsaturated fats.

Mary Schroepfer, MED
Nutrition Specialist
SchroepferM@missouri.edu