I continue to hear how many people talk about how they carb load before strenuous exercise or a long-distance event such as a marathon. But you should be aware that carb loading is an extremely destructive process. Let me explain.

In anticipation of a strenuous event, people often consume a large quantity of pasta the evening before. They also consume lots of bananas, sugary “energy” drinks or bars during the event under the belief that such a load of sugar and carbs will improve performance by loading up on liver glycogen, a stored source of sugar energy. Unfortunately, there are some serious problems with this line of thinking. It is not only unnecessary, but destructive to health, with some effects being permanent and irreversible.

Be aware that:

  • The original argument that carbs are necessary for maximum aerobic performance was based on studies conducted about 30-40 years ago in which elite athletes were deprived of carbs for one week. Aerobic performance, e.g., strenuous biking or running, was impaired, with previous performance restored by adding back carbs. This was interpreted as meaning that carbs are essential for physical performance. However, more recent evidence tells us that the lack of carbs leads to a conversion to relying on mobilization of fat for energy, an adaptation that requires 4-6 weeks, not days. In other words, if athletes are deprived of carbs and performance deteriorates, full performance returns in 4-6 weeks once muscles and other organs have adapted to the change in energy source. In some cases, performance with fat adaptation exceeds the level of prior carbohydrate-fueled performance.
  • High sugar/carb bolus intake raises blood glucose that, in turn, irreversibly glycates proteins throughout the body. The proteins in the lenses of your eyes become glycated, leading to cataracts. Collagen protein in skin and joint cartilage are glycated, leading to thinning of the skin and accelerated skin aging, and deterioration of joint cartilage that becomes brittle, leading to bone-on-bone arthritis. Small LDL particles are created by the flood of carbs that, in turn, are glycated; glycated small LDL particles are a potent cause for coronary heart disease, heart attacks, and sudden cardiac death. Carb loading therefore introduces significant and irreversible deterioration of multiple organs of the body,
  • Bolus consumption of sugar and carbs alters bowel flora, favoring proliferation of unhealthy fecal bacterial and fungal species such as Candida albicans. It is not uncommon to develop small intestinal bacterial overgrowth, SIBO, or irritable bowel syndrome, IBS, after several rounds of carb loading. Couple this with the marked increase in intestinal permeability that occurs in the 24 hours following a strenuous event—a period of increased endotoxemia and thereby increased insulin resistance and inflammation. My friend and founder of BiotiQuest, Martha Carlin, devotes her efforts to finding better, mostly microbial, solutions to Parkinson’s disease, since her husband was diagnosed with this condition at age 44. Martha interacts with a substantial Parkinson’s community. She has made the interesting observation that the majority of people in her Parkinson’s community were carb-loading long-distance athletes in their younger years. Could the combination of carb loading with the increased intestinal permeability that follows be a cause or contributor to Parkinson’s disease? It’s speculation, but potentially an important association.

The irony is that many people engage in strenuous aerobic activity for health. But the practice of carb loading is an incredibly unhealthy practice. It would be better to be fat-adapted and never carb load. I would also question the wisdom of engaging in long-distance efforts, given the increased intestinal permeability, though transient, and the growing number of people presenting with heart muscle diseases (cardiomyopathies), especially of the right side of the heart, and sudden cardiac death. Homo sapiens are adapted to running long distances to capture their prey, but not to extremes of such long-distance efforts.