Just as your car runs best on a certain type of fuel, so does the human body. Unfortunately the latest low-carbohydrate (CHO) fad diets are not the fuel mix the human body was designed to run on. Here are the main health risks associated with consuming a high-protein, low-CHO diet over the long run.

1. Heart Disease Risk Increases- Risk of heart disease is increased greatly on a low-CHO, low-fiber diet that is high in animal protein, cholesterol and saturated fat. All three raise serum cholesterol, particularly LDL or "bad" cholesterol. Elimination of high-CHO, high-fiber plant foods, that help lower cholesterol, compounds this problem. A high meat intake may excessively increase homocysteine levels and iron stores in the body. There is growing evidence that high levels of both may increase the risk of heart disease.

2. Cancer Risk Increases- Risk of many cancers is likely to increase when most fruits, vegetables, whole grains and beans are eliminated from the diet. The National Cancer Institute currently recommends, based on the bulk of scientific research, that you eat a plant based diet that is high-fiber and low-fat.

3. Poor Long Term Weight Control- There is no metabolic magic in low-CHO diets. Those who continue to lose weight after the first week do so because they decrease calorie intake. This can occur because of decreased dietary variety. Greatly limiting the number of foods that people are allowed to eat, reduces their food and calorie intake. But a reduction in variety most often leads to boredom and cravings over the long run. One recent study showed that a high protein meal leads to a greater tendency towards binging later in the day on foods that are high in sugar and fat.

4. Reduced Athletic Performance- Athletic performance is reduced on a low-CHO diet. Since the 1930's it has been known that a high-CHO diet can enhance endurance during strenuous athletic events. Mountain climbers and skiers should be warned that a ketogenic diet greatly increases the risk of mountain sickness.

5. Rising Blood Pressure with Age- Blood pressure will likely increase with age on a typical low-CHO diet. In part, this is because a high-CHO, high-fiber diet includes more fruits, vegetables, whole grains and nonfat dairy products. This diet was shown to lower blood pressure most likely due to its higher content of key minerals such as potassium, calcium and magnesium. Also low-CHO diets do not restrict salt intake, the main reason blood pressure rises with age.

6. Gout- An excess of uric acid in the body causes gout. This excess can be caused by an increased intake of foods high in purines, which are broken down into uric acid in the body. Meat, poultry, nuts, seeds, eggs and seafood are all fairly high in purines. Elevated levels of uric acid in the blood may lead to needle-like uric acid crystals in joints.

7. Kidney Stones- Both uric acid and calcium oxalate stones are more likely to form on a high protein, ketogenic diet than on a higher carbohydrate diet with more fruits and vegetables.

8. Osteoporosis- Over time, excess protein intake, especially from animal sources, increases the loss of calcium in the urine which may contribute to osteoporosis.

9. Fainting- Orthostatic hypotension, or a rapid drop in blood pressure when you go from lying down to standing, is caused by a loss of fluid and electrolytes and reduced sympathetic nervous system activity. Both of these occur when your body is deprived of CHO. This may result in dizziness or even fainting when you stand up quickly.

10. Keto breath- Keto-breath can be described as a cross between nail polish and over-ripe pineapple. This is common for dieters who consume so few CHO that they put their. bodies in ketosis.

Your best bet for permanent weight loss and control, as well as good health, is twofold: 1) increase the amount of fruits, vegetables, whole grains, beans and non-fat dairy products that you eat and 2) eliminate calorie-dense foods such as cookies, sugary desserts, bagels, crackers, chips, fries, pizza, candies, etc. Research on people who have successfully lost a lot of weight and kept it off long term, shows that the vast majority succeeded by consuming a low-fat, high-fiber diet coupled with regular exercise.

By Dr. Tames J. Kenney, PhD, RD, FACN, Nutrition Research Specialist, Pritikin Longevity Center. Dr. Kenney is on the Board of Directors for the National Council for Reliable Health Information and is Board Certified as a Specialist in Human Nutrition by the American Board of Nutrition. .