In the post-Atkins era, this might seem like strange advice: Eat carbohydrates to help you stay lean. But according to a study of 4,451 healthy Canadians, those whose diets contained the most carbohydrate had the lowest risk of being overweight or obese.
For the past decade, the debate over the best diet to maintain a healthy weight has been centred around carbohydrates. The late physician and cardiologist Robert Atkins won over many dieters to his high-protein, low-carbohydrate plan which, over the short term, produces greater weight-loss results than a diet high in carbohydrates.
But the long term is what counts when it comes to maintaining a healthy weight and studies have determined there's no difference between the diets and amount of weight lost after one year.
In fact, recent studies suggest that a high carbohydrate diet is indeed effective for losing weight and outperforms a high protein diet when it comes to losing body fat and lowering cholesterol and blood sugar.
The current study, published in the July issue of the Journal of the American Dietetic Association, assessed the diets and body weights of 4,451 healthy Canadians aged 18 years and older. The likelihood of being overweight or obese declined steadily as carbohydrate intake increased.
Compared to people whose diets provided the least carbohydrate (36 per cent of calories), those who consumed the most (64 per cent of calories) had a 40 per cent lower risk of being overweight or obese.
Overweight and obesity was defined as having a body mass index (BMI) of 25 or greater. (BMI is calculated as your weight in kilograms divided by the square of your height in meters. For adults, a BMI of 25 or more signals overweight; 30 more indicates obesity.) A higher carbohydrate diet was protective from overweight and obesity among older and younger participants, men and women, and people who never smoked.
A diet that is high in carbs such as whole grains, legumes, fruits and vegetables is also naturally low in fat and high in fibre. Fibre-rich foods add volume to meals, helping you feel full on fewer calories.
In the study, participants with the highest carbohydrate intake had a lower intake of calories, protein, total fat and saturated fat than the lower carbohydrate eaters. They also consumed almost double the fibre and more fruits and vegetables that those with the lowest carbohydrate intake.
Earlier research has also revealed that a high carbohydrate diet is good for the waistline. A 2008 study found that the Mediterranean diet – high in whole grains, fruit and vegetables – was as effective as the low carbohydrate diet at shedding pounds over a two-year period. What's more, among people with diabetes, this high carbohydrate diet did a better job at reducing blood sugar and insulin levels.
However, not all carbohydrates are good for you. Mounting evidence suggests that diets based on low glycemic index (GI) carbohydrates are better for weight control and health.
The GI is a scale that ranks carbohydrate-rich foods by how quickly they are digested and raise blood sugar compared to pure glucose. Foods that are ranked high on the GI scale are fast acting – they're digested quickly and, as a result, cause large rises in blood sugar and insulin, the hormone that removes sugar from the blood and stores it in cells. Examples include white bread, whole-wheat bread, baked potatoes, refined breakfast cereals, instant oatmeal, cereal bars, raisins, ripe bananas, carrots, honey and sugar.
Foods with a low GI release sugar more slowly into the bloodstream and don't produce an outpouring of insulin. Examples include grainy breads with seeds, steel cut oats, 100 per cent bran cereals, oat bran, brown rice, sweet potatoes, pasta, apples, citrus fruit, grapes, pears, legumes, nuts, milk, yogurt and soymilk.
