Your body needs and uses glucose for energy. Without it, you would not survive. It is important to understand that the debate is about whether or not you need to supply your body with sugar from your diet, or whether the metabolic pathways that generate glucose from non-carbohydrate substrates gluconeogenesis is the ideal mechanism.
One of the primary fuels your brain needs is glucose, which is converted into energy. This mechanism for glucose uptake in your brain has only recently begun to be studied, and what has been learned is that your brain actually manufactures its own insulin to convert glucose in your blood stream into the food it needs to survive. When your brain become insulin resistant when its response to insulin is weakened to the point that it stops producing the insulin necessary to regulate blood sugar it begins to starve and atrophy, causing many of the symptoms of dementia.
Fortunately, your brain is able to run on more than one type of energy supply. Ketone bodies may even be able to restore and renew neuron and nerve function in your brain after damage has set in. This was shown in Mary Newport research on coconut oil for the treatment of Alzheimer. Her research showed that coconut oil naturally contains 66% medium chain triglycerides, which are a primary source of ketones. When dieting, the majority of people who reduce carbohydrates tend to raise protein slightly, but they do not raise their fat intake due to the fat phobia that has been perpetuated for the last half-century. If carbohydrates are to be reduced to help maintain blood sugar, how much should they be reduced and what types should be taken away and eaten very sparingly?
One of the risks of promoting starchy carbohydrates is that most people should not be eating them! The sheer fact that two-thirds of American adults are overweight or obese, and one in four American adults have diabetes or are pre-diabetic, tells us that the majority, probably well over two-thirds of the US adult population needs to be very careful about eating foods that raise insulin levels. This category includes starches such as grains, breads, pastas, potatoes, peas, all products made from grain, and most fruits.
When you starve your body of sugars and starchy carbohydrates, your body starts to acclimatize itself to burning fatty acids and ketones. Ketones are what your body produces when it converts fat into energy, rather than glucose into energy. The glucose, which is converted into energy, fuels the brain. But does that mean you need dietary sugar for this process? Fortunately, the brain is able to run on more than one types of energy supply. So, even when it comes to something as essential as providing fuel for your brain, there is little or no evidence that consuming dietary sugars is necessary, as long as you provide it with the proper or likely preferential fuel, which is healthy fat!
Starches raise glucose which contributes to chronic disease. Raising blood glucose raises insulin, which increases insulin and leptin resistance. Avoiding insulin and leptin resistance is perhaps the single most important factor if you seek optimal health and longevity! Therefore consuming more than about 70-80 grams of carbohydrates, those being only non-starchy, per day, based on research cannot be recommended. Remember what those starchy carbohydrates do: 1 quickly convert into glucose, raising blood glucose, 2 blood glucose rises, your insulin and leptin levels rise in response; this mechanism is designed to optimize short-term survival, it is not healthy long-term, 3 immediate effects of spiking or surges of your insulin levels are well known and include vaso-constriction, inhibits fat burning, and reduced production of glycerol to make glucose, 4 repeated insults of elevations of insulin and leptin eventually lead to their resistance which are hallmarks of poor health!
If you are looking for a solid nutrition and eating plan based on solid scientific research, you must look at reduced carbohydrate (starch/sugar) intake and increased fat intake. This will radically reduce your carbohydrate intake. Most people will likely notice great improvement in their health by following this approach as they are currently consuming far too many grain, starch and sugar carbohydrates in their diet.