Low carb fatigue: is it caused by thyroid hormone changes?

Low carbohydrate diets remain among the most popular diets for the purposes of losing excess body fat. While all sorts of criticisms have been voiced about the alleged dangers of low-carb diets, more recent studies clearly show that such concerns are grossly overstated. A common critique involves ketosis. Ketosis involves a greater production of metabolic byproducts of incomplete fat metabolism known as ketone bodies. In uncontrolled cases of diabetes, ketones can rise to dangerously high levels, resulting in metabolic acidosis, a life-threatening condition. In contrast, ketones rise only modestly when carbohydrates are removed from the diet, with the lower the carb intake, the greater the degree of ketone production. Over the years, various studies have shown that a minor production of ketones is not only safe but desirable. Ketones can be used as a direct fuel source by muscles and the brain and provide a protein-sparing action that helps to preserve lean mass under stringent dieting conditions.

Recent studies that have directly compared low carb diets to other diets show clear superiority of low carb diets in terms of rate of fat loss. The faster the fat loss, the more chance of diet compliance. Some studies show that after a year, there is little difference in the effectiveness of low carb diets to the usual low calorie or low-fat diets. In short, the weight-loss rate is the same. But a closer inspection of such diets often reveals that those on low carb diets have gradually added back carbs into the diet, so are no longer on low carb plans. The other major critique of low-carb diets is that they pose a danger to heart health since such diets are often high in saturated fat. In fact, studies show several beneficial changes that occur with a low-carb diet. These include higher levels of protective high-density lipoprotein cholesterol (HDL), as well as lower blood triglycerides and lower blood pressure.

Still, when most people begin a low-carb diet, there is often a period of extreme fatigue. In most cases, this fatigue is temporary, caused by a change in metabolism. It takes an average of 2-3 weeks to switch from a predominantly sugar-burning machine to a fat-burning machine, and this often results in some feelings of fatigue. Various mechanisms are thought to cause this. Low carb diets provide a natural diuretic action, since glycogen, the stored form of carbohydrate in the body is rapidly broken down when carbs are restricted. This loss of glycogen leads to a loss of water (the diuretic effect) since each gram of glycogen is stored with 2.7 grams of water. Along with the water, common minerals may also be lost, such as sodium and potassium. Since these minerals function as "electrolytes," required for nerve transmission, when they are in short supply, a feeling of muscular weakness and fatigue may quickly ensue. The obvious solution is to replace these lost . . .