The Truth About Carbs

North Americans are drowning in messages about high-protein, low-carbohydrate diets and their promises of quick and easy weight loss

Are low-carb diets really healthy?

The high-protein, low-carbohydrate diet takes many forms, but the most popular is the one described by Dr. Robert C. Atkins in Atkins for Life (St. Martin's, 2003). Caloric intake is limited to 20-percent carbohydrates and increased to 30-percent protein. In contrast, the average Canadian diet is 53-percent carbohydrates and 12-percent protein, not far from Canada's Food Guide for Healthy Living.

The Atkins plan is founded on a diet that cuts out processed foods and encourages high-fibre foods and protein. As most North Americans have a low consumption of protein, encouraging more protein consumption is a good idea, particularly when nuts, fish, and soy are the protein sources.

Eliminating white processed carbohydrates is also good nutritional advice. Highly processed foods have a high-glycemic index. As simple carbohydrates, they are quickly digested into glucose causing a rapid rise in blood-sugar levels and a mirroring insulin response. Because the rise and removal of blood sugar happens quickly, we feel hungry soon after eating high-glycemic foods, despite sufficient caloric intake. Therefore, high-glycemic index foods can result in overeating and may be associated with obesity.

Too Much Protein?

An almost all-protein diet, however, may have negative physiological impacts, such as an increased production of uric acid in the body, which can cause gout. To metabolize and eliminate the byproducts of extra protein in the diet, the liver and kidneys must work harder, which may speed the progression of diabetic renal disease. High protein consumption may also compromise bone, joint, heart, liver, and kidney health.

Too Many "Bad" Fats

Creators of high-protein diets argue that choosing a high-fat diet is good because fat slows the absorption of glucose into the bloodstream. However, a diet rich in animal protein, saturated fat, and cholesterol has been shown to raise LDL (bad) cholesterol levels, an effect augmented by the lack of high-fibre, high-carbohydrate fruits and vegetables, which can lower cholesterol.

No Fruit and Veggies

Higher protein consumption, in the absence of adequate fruits and vegetables, can cause an increase in calcium loss through the urine, which may increase the risk of osteoporosis. We know that adequate fruit and vegetable intake can be associated with lower risk for heart disease. A diet restricted in fruits and vegetables will cause deficiencies in vitamins and minerals and may result in an increased risk for cancer.

Some Carbs are Better than Others

The truth is that we need carbohydrates. A diet lacking in carbs is like a car without gas. A lack of carbohydrates results in the use of glycogen stores in the muscle, causing early fatigue during exercise. Restrictions on carbohydrate consumption can result in the loss of lean muscle tissue.

The truth is that some carbohydrates are better than others. Avoid white breads and highly processed foods that cause high glucose peaks in the bloodstream. However, complex carbohydrates such as fruits, vegetables, and most whole grains have a low-glycemic index because they are harder to break down. Our blood sugar rises more slowly, our insulin removes the glucose slowly, and it takes longer before our blood sugar lowers enough to stimulate hunger.

When it comes to diets, know the facts.