Results

Weight loss
Most people can lose weight on almost any diet plan that restricts calories and what you can eat — at least in the short term. Over the long term, though, studies show that it's common to regain the lost weight, regardless of the diet plan you follow. Some studies also have shown that people who continued to follow certain low-carb diet plans for two years lost an average of nearly 9 pounds (4.1 kilograms) overall, which is similar to the amount of weight lost on higher carbohydrate diets. And it may not be just cutting carbs that leads to weight loss. Some studies show that you may shed some weight because you eat less on low-carb diets because the extra protein and fat keep you feeling full longer.

Other health benefits
Some low-carb diets, including the Atkins Diet, say that their eating plans can prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and cardiovascular disease. In fact, almost any diet that helps you shed excess weight can reduce or even reverse risks factors for cardiovascular disease and diabetes. Most weight-loss diets — not just low-carb diets — may improve blood cholesterol or blood sugar levels, at least temporarily. Low-carb diets may improve HDL cholesterol and triglyceride values slightly more than do moderate-carb diets. And it may not only be how many carbs you eat but also the kinds of carbs you eat that are important to your health. Whole grains, legumes, vegetables, fruits and low-fat dairy products, for instance, are generally healthier than are carbs from sweets and processed and refined grains, such as potato chips, white bread and white rice.

Risks

If you suddenly and drastically cut carbs, you may experience a variety of temporary health effects, including:

  • Headache
  • Dizziness
  • Weakness
  • Fatigue
  • Constipation

In addition, some diets restrict carbohydrate intake so much that they can result in nutritional deficiencies or insufficient fiber. This can cause such health problems as constipation, diarrhea and nausea. Eating carbs that are high fiber, whole grain and nutrient dense can improve the health profile of some low-carb diet programs. And some low-carb diets, such as Atkins, now recommend taking small amounts of extra salt, along with vitamins or supplements, to help prevent diet side effects.

It's also possible that severely restricting carbohydrates to less than 20 grams a day can result in ketosis. Ketosis occurs when you don't have enough sugar (glucose) for energy, so your body breaks down stored fat, causing ketones to build up in your body. Side effects from ketosis can include nausea, headache, mental fatigue and bad breath.

It's not clear what kind of possible long-term health risks a low-carb diet may pose because most research studies have lasted less than a year. Some health experts believe that if you eat large amounts of fat and protein from animal sources your risk of heart disease or certain cancers may increase.

Oct. 11, 2011 See more In-depth