Refined carbohydrates should be limited for weight management.

Can you eat too few carbohydrates? Can you eat too many carbohydrates? Ask different people and you get different answers. What are the facts on carbohydrates? Let's look at the science versus the cultural zeitgeist.

Low carbohydrate diets have been much maligned by the media and many people believe they're unhealthy. The misinformed will readily tell you low carb diets limit fruits and vegetables, lack fiber and vitamins, have too much fat, and that you'll only lose water weight. They warn of harmful side effects like the dangers of ketosis and weakened kidneys and bones. They'll tell you you'll lose only water weight, and you'll starve your brain. All of the above are myths.

Read "What is gluconeogenesis?" and why low carb diets don't starve your brain.

So, how many carbohydrates in your diet are too many? How many carbohydrates are too little?

High carbohydrate diets in which you eat up to 60 percent of your calories from carbs per the US government diet pyramid, particularly from refined grain products and starches, didn't exist for most of human existance. We ate mostly animals, berries and other fruits when they were in season, roots, nuts, and some wild plants like herbs untilagriculture was developed. The US department of agriculture developed the food pyramid to promote sales of argricultural products. These products like corn, wheat and sugar are high in carbohydrates and eating too many makes us fat.

According to research, pre-agricultural humans were taller and healthier than post agricultural humans. See references below. For an eloquent explanation, see Dr. Mary Dan Eades interview with Tom Naughton in the documentary "Fathead" in which shes says, "After agriculture developed human health devolved."

The development of agriculture, meaning the growing of predominantly carbohydrate crops like corn, wheat, sugar, and soy, was a boon to our food supply. But abundance alone doesn't make a food healthy or necessary for survival. Crops like whole grains were not eaten in abundance, if at all, by humans for most of our existance. 

This paleolithic dietary approach eventually evolved into our modern low carboydrate diets like Atkins, South Beach, and Protein Power. While these diets are in line with the way humans ate for centuries, the media, the government, and many in the medical world still discourage their use and promote a high carbohydrate diet. One of their last existing arguments against low carbohydrate diets is that eating low carb starves your brain. That's a persuasive arguement but doesn't hold water on closer inspection. 

While it's true that the human brain runs on glucose, science has proven the human body doesn't need carbohydrates to make the glucose it needs. Yes, your body can use dietary carbohydrates to make glucose. But the actual physiological demand for glucose and the amount of carbohydrates most of us eat is way off balance. The arguement that we shouldn't limit carbohydrates to keep our brains from running out of fuel is a subterfuge. Modern low carbohydrate diets provide ample glucose even on "induction phases." Only a small minority of us ever need to rely on our body's ability to create glucose through gluconeogenesis.

So can we eat too many carbohydrates? Yes. Americans eat too much of everthing on average. But the real issue in nutrition today is that the average American eats too many carbohydrates. Too much blood sugar from eating too many carbohydrates - particularly refined carbohydrates - leads to medical conditions like metabolic syndrome, insulinemia, diabetes, inflammation linked to heart disease, obesity, and cancer.

Your body doesn't just convert the refined carbohydrates from foods like sodas and bagels into blood sugar. Nearly all carbohydrates including starchy vegetables like potatoes, whole grains, and fruits convert to blood sugar. The real problem with the American diet isn't that we're limiting carbohydrates. Simply, it's that we are eating too many carbohydrates.

People tolerate different dietary levels of carbohydrates. Generally, individuals will have to experiment with their personal carbohydrate intake to get a feel fo how much is too much. If you gain weight easily, it's a good idea too limit your intake of starchy carbs and replace them with proteins, fats, and carbohydrates from higher fiber fruits and vegetables with a lower glycemic index.  

References:

How High Carbohydrate Foods Can Raise Risk For Heart Problems

ScienceDaily (June 27, 2009) — Doctors have known for decades that too much carbohydrate-laden foods like white bread and corn flakes can be detrimental to cardiac health. In a landmark study, new research from Tel Aviv University now shows exactly how these high carb foods increase the risk for heart problems.

Scientific Proof Carbohydrates Cause Disease.

Study: Neanderthals Ate Mostly Meat, June 14, 2000  Washington - If you ever have a Neanderthal over for a backyard barbecue, forget the salad, the corn on the cob and the baked potato. All he'll want is the meat, and lots of it.

Larsen, Clark Spencer (01 November 2003). "Animal source foods and human health during evolution". Journal of Nutrition 133 (11, Suppl 2): 3893S–3897S. PMID 14672287.

Elton, S. (2008). "Environments, adaptations and evolutionary medicine: Should we be eating a ‘stone age’ diet?". in O’Higgins, P. & Elton, S.. Medicine and Evolution: Current

Applications, Future Prospects. London: Taylor and Francis. ISBN 1420051342. Cordain, Loren (1999). "Cereal grains: humanity's double-edged sword" (PDF). World review of nutrition and dietetics 84: 19–73. doi:10.1159/000059677. PMID 10489816.