The popularity of low-carb, ketogenic and other Atkins-style diets are fueling an intense fascination around Carbohydrates. As a dietitian I feel it’s my duty to deepen our understanding of this topic.
The world’s staples are carb-heavy; these include cassava, corn, plantain, potato, rice, sorghum, soybean, sweet potato, wheat and yam. Fruits and vegetables, the foundation of a well-balanced diet, also contain carbohydrates. Even dairy contains milk sugar, which is a carb.
Importance of carbohydrates
Carbohydrates supply glucose, the fuel source that our bodies use. Our body runs on calories, and it gets those calories by metabolizing carbohydrates, fat and protein from our food. Since our body spares protein for rebuilding and repairing tissue, carbohydrates and fat are by far the fuel of choice. While every cell is capable of burning glucose for energy, the same is not true for fat.
Certain organs and tissues require glucose. Our brain and red blood cells rely on the plentiful glucose in carbohydrates. Through gradual adaptation, the brain can learn to use fat in the form of ketone bodies, but our blood cells will always rely on glucose. In fact, our body fights really hard to keep our blood glucose levels within a narrow window. Once you dip below 20mg glucose/dL of blood you risk slipping into coma or having a seizure. This biological fact is partly what drives the daily recommendations for carbohydrates.
The National Academy of Medicine sets the recommended dietary allowance at 130 grams per day. This is the minimum amount of carbohydrates needed to provide enough glucose for the brain and red blood cells from carbohydrates.
The Dietary Guidelines for Americans set macronutrient distribution for carbohydrates at 45–65% of total daily calories. For someone who eats a typical 2,000-calorie diet, this is 225–325 grams of carbs per day.
The World Health Organization and Food and Agriculture Organization recommend that 55% of total calories come from carbohydrates per day.
Can we function without carbs?
Protein and fat can provide glucose. The healthy human body is fully capable of reforming the amino acids from protein into glucose. Even the breakdown of fat for energy yields a bit of glucose. If an individual is eating enough calories, even if those calories are mostly from fat or protein, that person can still satisfy the glucose needs of their brain and blood cells and maintain their blood glucose at a normal level.
There is no such thing as “carbohydrate deficiency”. Nutrition science defines a nutrient as “essential” if we must get it from the diet because our body can’t make enough of it to meet our needs, so that we may not end up with an impairment or disease. This is not the case with carbohydrates.
The Atkins diet advocates followers eat as little as 20 grams of carbohydrates per day! To give you an idea of what this means: 20 grams is the amount of carbs in 1 small (6-inch) banana.
The classic ketogenic diet is 80–90% fat. It was originally used as a therapy for epilepsy but is now gaining popularity for use in weight loss.
The traditional Inuit diet, which is what the natives of northern Canada subsisted on for many years, is empty of refined sugar and grains. Instead, there’s plenty of fresh seal, walrus and other marine life on the menu. The diet on average has 23% calories from protein, 39% calories from fat and 38% calories from carbohydrates.
When it comes to choosing how low-carb you should go, keep in mind that:
- Everyone responds differently to varying levels of carbohydrates. Our bodies are unique, so what works for one person may not work for another. The key is to do some research, and then experiment to figure out what works best for you. Enlisting expert guidance from a dietitian can make this process easier.
- The best diet is one that can be followed over time. Consistency is the key to a healthy lifestyle. Setting yourself up with a plan that allows 20 grams of carbs per day may not be the best way to achieve this. A balanced diet is one that allows flexibility for you to fit in foods you enjoy regardless of carbohydrate content.
- “Low-carb” can be a healthy lifestyle. Most low-carb diets don’t go as low as you may think, hovering around 35–40% of calories from carbohydrates. For many, the term “low-carb” has become synonymous with eating less refined carbs and added sugar and eating more fruits and vegetables.