Dear Dietitian,

Many of my friends are following low-carb diets.  They say they have lost weight and feel great, but is this a healthy way to lose weight?

--Sara

Dear Sara,

As we know by all the weight loss diet books on the shelves, when it comes to cutting calories, there are many approaches.  Low carbohydrate, or “carb,” diets have gained popularity in recent years because of their ability to produce short-term weight loss and improve cholesterol levels. One dieter following a low-carb routine reported he liked the simplicity of the diet, “If it is a carbohydrate, don’t eat it. I don’t have to think about it.” While low-carb diets provide some carbohydrates each day, one benefit of this diet is satiety, or the feeling of being satisfied. Protein and fat, the foods that replace carbohydrates, move out of the stomach more slowly than carb foods, resulting in longer sensations of feeling full.

Until recently, the long-term effects of low-carb diets have not been studied.  The Prospective Urban Rural Epidemiology (PURE) study, Dehghan, et al. found that diets high in carbohydrates (77% daily calories) were associated with increased death rates; however, diets high in fat (35% daily calories) were associated with lower death rates. This study, which was published in The Lancet, was criticized for its methods.

In another study published in The Lancet, Seidelmann, et al. found that both diets high in carbohydrate (>70% total calories) and low (<40% total calories) have been shown to increase all-cause death. A 50-55% energy intake from carbohydrate was found to have the lowest risk of death.

Since the conflicting results of these studies were confusing to me, you may also find them confusing. This is the takeaway:  Not every carbohydrate is created equally when it comes to nutrition. Carbs range from fruits and vegetables to whole grains to sugar. A healthy plan is to choose carbs high in fiber (fruits, vegetables, whole grains) and low in sugar. 

If you choose to cut carbs, the healthiest approach is to replace them with lean meats and vegetable sources of protein like nuts, seeds, and peanut butter.  Choose polyunsaturated or monounsaturated over animal fat. Monounsaturated fats are found in olive oil, canola oil, avocados, and nuts, while polyunsaturated fats are found in vegetable oil and seeds, as well as fatty fish, like salmon and trout. Keep it simple, and be healthy.

Best health,

Dear Dietitian