Diabetes, Carbohydrates, and Weight Gain: The Big Fat Lie

Fat is the bugaboo of the American diet. There’s no denying that nearly two-thirds of Americans and similar large numbers in Australia, Canada, and the UK are overweight. There is also no doubt that some fats are better than others. It is a myth, however, that dietary fat in and of itself is the cause of overweight, high cholesterol, or heart disease.

Most body fat for most people does not derive from dietary fat, but from carbohydrate converted to blood sugar and then stored in fat cells. Suppose you eat a platter of pasta. If you are not diabetic or you are doing a good job of controlling your blood sugars, your natural or injected insulin levels will rise to cover the flood of blood sugar entering the bloodstream about an hour after you eat your meal.

Every gram of blood sugar that is not burned or stored as glycogen in the liver (which maintains about a thousand-calorie “buffer” for the body’s short-term energy needs) is stored as fat. You can acquire more body fat from a 250-calorie fat-free oatmeal muffin than from a 3-1/2 oz (100 gram) steak.

But you say, really? The 250-calorie fat-free muffin contains about 50 grams of carbohydrate. If you weigh 150 pounds (68 kilos) and you don’t get any exercise after eating the muffin, your body uses about 20 grams of carbohydrate over the two hours after your meal for respiration, tissue growth and repair, making enzymes and hormones, digesting food, and other basal metabolic activities.

If you overeat carbohydrates only occasionally, your liver can store them as glycogen. The way the chemistry of the liver works, however, every molecule of glycogen, has to be stored with three molecules of water, and the carrying capacity of the liver is only a little over a pound (500 grams) of emergency carbs. And if the glycogen buffer in your liver is not full, the 30 grams of carbohydrate in the muffin are converted to about 120 grams of energy storage that goes right to your midsection.

What if you are diabetic? If you are a type II diabetic, the effects of carbohydrate on fat storage are magnified.

The bodies of type II diabetics still make insulin. In the early stages of the disease, type II diabetics actually make more insulin than people who do not have diabetes, but their bodies do not use it efficiently for moving glucose into cells.

Type II diabetic bodies are wonderfully efficient, however, at using insulin to move fat into fat cells. So overindulgence in carbohydrate sets up a vicious circle. Excess carbohydrate consumption triggers release of excess insulin. The insulin does a poor job of storing glucose, but it does a great job of storing fat. And the fatter you get, the more your cells resist the action of insulin for storing glucose. Less and less glucose gets pulled out of the bloodstream, but fat cells store more and more fat.

So, if you are diabetic, it's not a matter of any kind of lack of discipline if you are fat. Fat is a symptom of diabetes, not the other way around.