As a new diet goes head to head with the Dukan, Michelle Gelok gets to the bottom of the carbohydrate question.
The truth about carbs
Carbohydrates have endured a storm of controversy over the past 10 years, and have emerged with a less-than-desirable image.
The Atkins Diet, the granddaddy of low-carbohydrate diets, actually started life in 1972, when Dr Robert Atkins published his first book, Dr Atkins’ Diet Revolution, urging followers to shun foods such as bread, potatoes and pasta, and stock up on protein-rich foods in order to shed unwanted pounds. But it wasn’t until the early to mid-2000s that low-carb dieting really becamse a craze. At the height of its popularity in 2004, surveys showed that as many as 28 per cent of Americans were following a low-carb diet.
The popularity of low-carbohydrate diets waned in recent years, although many people retained a lingering suspicion that all carb-heavy foods are inherently unhealthy and fattening.
And now two diet books are reigniting the debate on carbohydrates and once again bringing them to the forefront of consumer’s minds. The Dukan Diet, a high-protein, low-carbohydrate, low-calorie weight-loss eating plan, designed by a French doctor, has been gaining popularity in much of Europe over the past few years and is currently enjoying a surge in interest after it was rumoured that the Duchess of Cambridge followed the diet in anticipation of her April nuptials. Not as extreme as the Atkins diet, the Dukan diet still limits the consumption of carbohydrates, some of which are rich in important vitamin, minerals and antioxidants, such as beets and carrots.
At the same time, a very different kind of diet is also making headlines. The Carb Lovers Diet is designed by a registered dietician and challenges the widespread belief that carbohydrates cause weight gain. Unlike low-carbohydrate diets, The Carb Lovers Diet takes a more balanced approach to eating and aims to put healthy carbohydrates back on the dinner plate. The diet is based on resistance starch, a type of carbohydrate that resists digestion in the small intestine and can prolong feelings of fullness.
Preliminary studies show that resistance starch, found in bananas, brown rice and beans, may play a role in weight loss, lowering blood glucose levels and improving digestive health. While the diet is based on sound science, it’s possible to go overboard in trying to conquer people’s fear of carbohydrates. A claim on its site that pizza, pasta, bread and potato chips can make you thin doesn’t really do the diet justice and risks adding to consumer confusion.
With so much conflicting advice on carbohydrates, it’s no wonder dieters are left scratching their heads. So what is the bottom line when it comes to carbohydrate consumption?
While they often get clumped together, low-carbohydrate diets can vary in terms of their restrictions, benefits and risks and some are certainly healthier than others. Extreme low-carbohydrate diets can shift the body’s metabolism into ketosis, a potentially dangerous state that can cause bad breath, nausea, fatigue and, in extreme cases, kidney failure. When animal sources of protein, such as meat, eggs or cheese account for a large percentage of calories in a low-carbohydrate diet, dieters may be at an increased risk of death. One study from Harvard researchers found that when people followed a low-carbohydrate diet rich in animal products, they were at an increased risk of death from cancer and cardiovascular disease, compared to people following a low-carbohydrate diet based on plant protein, which can be found in beans, legumes and soy.
Despite their potential heath risks, low-carbohydrate diets shouldn’t be dismissed completely. They may be effective at short-term weight loss. One study published in the Journal of the American Medical Association in 2007 found that when compared to moderate and high-carbohydrate diets, a low-carbohydrate diet was the most effective at weight loss in overweight women. However, the restrictive nature of low-protein diets means they can be difficult to follow in the long term.
In terms of weight loss, the truth is just about any diet, whether it’s high in carbohydrates or low in carbohydrates, can lead to weight loss. That’s because any diet that restricts calories, whether from carbohydrates, protein or fat, will cause weight loss. And despite what many people believe, carbohydrates will not make you fat unless you eat too many of them.
There seems to be a lot of misinformation about what “carbs” really are. Carbohydrates are all the sugars, starches and fibres found in the food we eat. Despite their reputation as being unhealthy, the truth is we couldn’t survive without them.
Carbohydrates are the main source of energy for the body, and brain cells rely on them to function properly. In fact, the Institute of Medicine in the US recommends that adults get between 45 and 65 per cent of their calories from carbohydrates, whereas some low-carbohydrate diets recommend as little as 20 per cent. Most government-based healthy eating guidelines reflect the importance of a balanced diet that contains carbohydrates. Both the The Eatwell Plate, from the NHS in the UK, and the brand-new MyPlate, revealed by Michelle Obama and the US department of agriculture last week, promote a diet rich in carbohydrates from fruits, vegetables and whole grains.
However, not all carbohydrates are created equal, and as a whole, carbohydrates should not be vilified, or glorified. In the same way that there are good and bad fats, science is showing us there are also good and bad carbohydrates. One method of classifying the quality of carbohydrates is the glycaemic index, a measure of how quickly carbohydrates raise blood-glucose levels. Foods with a high glycaemic index are digested quickly and cause a rapid rise and fall in blood glucose levels, while foods with a low glycaemic index are slowly digested and provide a steady supply of glucose to the body.
Foods with a high glycaemic index include many processed and refined foods, such as white bread, white rice and pure sugar, whereas foods with a low glycaemic index include most fruits, vegetables, whole grains, legumes and tend to be rich in dietary fibre. Studies show that a diet rich in foods with a low glycaemic index may decrease the risk of heart disease, assist in weight loss and management, reduce the risk of type 2 diabetes, and play a critical role in the management of the disease.
Of course, a hefty dose of common sense can also go a long way at distinguishing healthy carbohydrates from unhealthy ones. Generally speaking, highly processed and refined carbohydrates, such as white bread, potato crisps, candy and cookies can’t compare to the nutritional quality of less processed carbohydrates, such as fresh fruits and vegetables, nuts, legumes and whole grains, such as oatmeal, barley, corn and brown rice.
The bottom line is that carbohydrates have an important role to play in a healthy diet. When chosen carefully, carbohydrates can help decrease the risk of chronic disease, such as cancer and heart disease, assist with weight loss and management and provide a valuable source of vitamins, minerals, fibre and disease-fighting antioxidants.