The Bad Effects of a Low Carb Diet

Introduction

Following a low-carb diet has been shown to have many benefits such as weight loss, reduced cholesterol levels, and lowered blood pressure. However, according to the Institute of Medicine, the brain needs at least 130 grams of carbohydrates per day in order to function properly. Most low-carb diets require fewer than 130 grams of carbohydrates daily, especially during an "induction phase" when it is common for dieters to only consume 20 grams of carbs (Bell and Sears, pp. 357-77). Although until recently there has been little research regarding the effects of a low-carb diet on brain functioning, the latest research finds that eating a diet low in carbohydrates does have a negative impact on brain functioning.

The Bad Effects of a low Carb Diet

Although low-fat diets have been the standard recommendation for weight reduction, fat intake among the United States population has decreased during the last 20 years while the number of individuals who are obese has increased to epidemic proportions. In addition, obesity-related chronic conditions such as cardiovascular disease and diabetes have also dramatically increased. The US Department of Agriculture's Food Guide Pyramid Diet is a high-carbohydrate, low-fat diet that advocates consumption of grains, fruits and vegetables at the expense of fat. Low-carbohydrate, high-fat diets (e.g., Atkins Diet, Zone Diet, South Beach Diet) have gained increasing popularity despite neither sufficient evidence about their long-term effectiveness or safety (Pirozzo, et al, pp. 83-90), nor clear consensus as to what amount of carbohydrates per day constitutes a low-carbohydrate diet. This editorial presents the current evidence-based research findings regarding low-carbohydrate, high-fat diets.

The Atkins Diet focuses on the consumption of fat and protein as primary caloric energy sources, while severely restricting carbohydrates. The Atkins Diet claims to be effective at producing weight loss despite ad libitum consumption of fatty meat, butter, and other high-fat dairy products, restricting only the intake of carbohydrates to fewer than 30 grams per day. The Zone Diet is another new fad in low carbohydrate dieting (Pirozzo, et al, pp. 83-90). The Zone is a 40% carbohydrate, 30% protein and 30% fat eating plan that advocates only sparing use of grains and starches and a precise 0.75 protein to carbohydrate ratio required with each meal.5 Similar to the Atkins Diet, the South Beach Diet begins with a two-week ban of fruit, bread, potatoes, baked goods, sweets, cookies, ice cream and alcohol, with subsequent stages that permit adding back foods while supposedly maintaining initial weight loss. The South Beach Diet claims to differ from Atkins by pushing the "right carbs" instead of no carbs. The South Beach diet allows meat, but unlike Atkins, it warns against saturated fat and encourages consumption of fish and chicken. One hypothesis for the accompanying weight loss observed with these low-carbohydrate, high-fat diets may be that severe restriction of carbohydrate intake leads to depletion of glycogen stores, excretion of glycogen-bound water, and a resultant ketogenic state that is appetite suppressing.

Large 'randomized controlled trials have shown that reduction of fat ...