By Adriana Selwyn and Derek Yach
The low-carbohydrate diet phenomenon is the latest in a long line of diets claiming to be the solution to rapidly rising rates of lifestyle-related chronic diseases. It comes as no surprise then that on Feb. 19-22, the world's first International Low Carb High Fat Health Summit will take place in Cape Town, South Africa. The four day summit is co-hosted by Tim Noakes, passionate low-carb crusader and proponent of the Banting diet, which has taken South Africa by storm.
Following the diet may well result in weight loss, partly because when dietary carbohydrates (pasta, potatoes, fruit, bread, legumes) are restricted, cells have to break down muscle and fat stores for energy, and primarily because of the overall lower calorie intake. However, research indicates any diet that reduces calorie intake, regardless of protein, carbohydrate or fat composition, will result in weight loss and associated metabolic benefits. Essentially, eating less of everything will lead to weight loss.
However, when a diet almost entirely eliminates a food group, questions need to be asked:
What nutrients are you missing out on?
Whole grains, dried beans, legumes and fruit (all of which are to be eliminated or restricted on the Banting diet) provide us with important phytonutrients, vitamins, minerals and fiber. A high fiber intake is associated with reduced risk of colorectal cancer.
What are you substituting it with?
When you reduce or cut out one food group, you inevitably increase consumption of another. In the case of the Banting diet, that leads to more fat. Noakes pays no attention to the importance of the type of dietary fat, but the evidence is clear that reducing saturated fat (found in animal meats, butter, cream) and replacing it with mono and polyunsaturated fat (fish, avocado, olive oil) is best for optimal cardiovascular health and reducing risk of Type 2 diabetes.
How sustainable is the diet?
How long can an individual sustain such restrictive dietary patterns, and what happens when they crack? A return to former diet habits will likely result in weight regain.
One also can't ignore the fact that indiscriminate red meat consumption has negative impacts on health -- ranging from increased risk of colorectal cancer and diabetes to greater risk of death from cardiovascular disease and cancer -- and the environment.
Experiences in South Africa with the Vitality Healthy Food program, where cash-back rebates for healthy food purchases resulted in a shift away from unhealthy foods, offers a unique example of how healthy diets are more sustainable. Estimates of the environmental impact of this shift (specifically purchases of more fruit and vegetables and less beef and pork) show an 8 percent to 13 percent decrease in land use, a 7 percent to 12 percent decrease in water use, and an 8 percent to 10 percent decrease in greenhouse gas emissions.
Diets that focus on overall dietary patterns, such as the Mediterranean diet (which emphasizes fruits, vegetables and whole grains, moderate amounts of healthy fats, nuts and fish, and limited intake of sweets and red meat) have clear benefits on health and the environment, and unlike diet fads that come and go, have stood the test of time. Guidelines, such as those from the American Heart Association, are increasingly focused on such dietary patterns rather than recommendations for individual nutrients.
More importantly, no single nutrient is responsible for the obesity epidemic. Placing the blame on carbohydrates does nothing but add confusion to an environment already saturated with mixed nutrition messages, and distracts us from addressing the real cause of the obesity epidemic: modern-day environments. Humans have always relied on carbohydrates for energy. Our physiology has not changed over the past 50 years, our environment has; the result being diets high in calorie-rich, nutrient-poor processed foods, and excessive portion sizes.
The way to tackle diet-related diseases is to create environments where healthy food is available and the easiest choice; and where small portion sizes are the norm. At the end of the day it is a simple message of moderation. Dr. David Katz insightfully noted that we so often neglect warning signs and root causes of preventable events, only to scramble for solutions once we reach crisis point. So it was with Hurricane Katrina, Ebola and now obesity. We must direct resources towards real solutions, now.