23 March 2004 | Filed under Low Carb : Exercise
Do Athletes Really Need High-Carbohydrate Diets?

By Anthony Colpo.

March 22, 2004

Brian Maxwell, founder of the multimillion-dollar PowerBar empire and a former world-class marathon runner, died of a heart attack on Friday, March 19. Maxwell and his nutritionist wife Jennifer, co-founded the popular energy bar company in 1986, which they eventually sold to Nestle SA for a reported $375 million in 2000.

For those not familiar with PowerBars, they are a sugar-rich, low-fat bar that have been heavily promoted to recreational and competitive athletes alike. That a glorified candy bar could achieve such monumental success when marketed as an athletic aid is due in no small part to the widely-held misconception that "athletes need lots of carbohydrates for energy".

As this author found out the hard way during the nineties, regular vigorous physical activity does not guarantee protection against the deleterious effects of a high carbohydrate diet. Despite daily workouts, my "healthy" low-fat, high-complex carbohydrate diet raised my blood pressure and seriously disrupted my blood glucose metabolism. These effects vanished after commencing a low-carbohydrate diet.

Brian Maxwell joins the late Jim Fixx as yet another high-carb consuming runner whose athletic background did little to counter the health-destroying effects of excessive carbohydrate ingestion.

Athletic Nutrition: More Carbs or More Fat?

One of the problems with many athletes is that they simply do not eat enough to meet the energy needs of their training activities. A recent review by researchers from the University at Buffalo, New York, highlighted several studies in which subjects with reduced energy intakes (500 to 800 kcal/day below estimated expenditure) showed reduced endurance exercise times. Increasing the subjects' caloric intake to match expenditure by increasing carbohydrates significantly increased their time to exhaustion by approximately 20% at exercise intensities of 70% and 80% of Vo2max. However, increasing the total caloric intake to meet expenditure by using fat brought about further significant increases in endurance time - an extra 40% over and above that produced by consuming extra carbohydrates! In these studies, the percentage of fat was raised from 15% to between 30% and 42% of total calories, while carbohydrates were limited to 35-40% of calories.(1)

These studies not only show that low-fat, high-carbohydrate diets are in no way essential for optimal athletic performance, but are in fact inferior to higher fat diets.

Whether Maxwell's death attracts anywhere near the media attention that was awarded to the widely-misconstrued contents of the late Dr. Atkins' leaked death report remains to be seen, but athletes should know that the chronic consumption of high-carbohydrate diets may indeed have potentially adverse health consequences, which regular exercise may not necessarily ameliorate. Chronic consumption of a high-glycemic load diet has been linked to increased risk of heart disease,(2) breast cancer,(3) diabetes,(4,5) and pancreatic cancer.(6)

Related articles:

Popular Energy Bars Raise Blood Sugar and Insulin Levels

References

1) Pendergast DR, et al. A Perspective on Fat Intake in Athletes. Journal of the American College of Nutrition, 2000 19 (3): 345-350.

2) Liu S, et al. A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women. American Journal of Clinical Nutrition, 2000; 71: 1455-1461.

3) Higginbotham S, et al. Dietary glycemic load and breast cancer risk in the Women's Health Study. Cancer Epidemiol Biomarkers Prev. 2004 Jan; 13 (1): 65-70.

4) Salmeron J, et al. Dietary fiber, glycemic load, and risk of NIDDM in men. Diabetes Care, 1997; 20 (4): 545-550.

5) Salmeron J, et al. Dietary fiber, glycemic load, and risk of non-insulin-dependent diabetes mellitus in women. Journal of the American Medical Association, Feb 12, 1997; 277 (6): 472-477.

6) Michaud DS, et al. Dietary Sugar, Glycemic Load, and Pancreatic Cancer Risk in a Prospective Study. Journal of the National Cancer Institute, 2002; 94: 1293-1300.

7) Shaw GM, et al. Neural tube defects associated with maternal periconceptional dietary intake of simple sugars and glycemic index. American Journal of Clinical Nutrition, 2003; 78 (5): 972-978.

Source: theomnivore.com