I was chatting with a prospective client last week about training with Athlete Architecture. We talked about training philosophies, race scheduling, and nutrition. She is a strong CAT 3 cyclist and was asking about the affects of Diet Coke on athletic performance. Now I am no nutritionist or dietician, but I like to think I have a decent grasp of the food groups and how athletes can better feed themselves to improve performance. My advice usually starts with the 8 words of Michael Pollan uses to describe how we should all eat, athletes included:

Eat real food,

Not too much,

Mostly plants.

But her question did spark my interest into what exactly is in that little aluminum can and how the ingredients affect our bodies. Here are the disturbing facts.

Zero calories doesn’t mean zero caloric effect. Researchers from UT Health Science center in San Antonio found that weight gain in subjects who drink diet soda is attributed to aspartame, the artificial sweetener. Aspartame releases glucose into the blood stream and when the liver detects too much circulating glucose, the excess is converted to body fat. This might be the reason why people who drink more than two diet sodas per day have a 500% waist expansion over 10 years vs. those who don’t drink any soda. Conclusion: Weight gain is not an endurance performance enhancer.

Aesthetics can be ugly. The caramel coloring in sodas, which is present purely cosmetic, contains 2-methylimidazole and 4-methylimidazole, both of which cause cancer in animals. According to California's strict Proposition 65, caramel coloring makes the list of chemicals known to cause cancer. Just 16 micrograms per person per day of 4-methylimidazole is enough to pose a cancer threat, and most colas, contain 200 micrograms per 20-ounce bottle.

Love that tangy-ness. Phosphoric acid is found in all sodas as a preservative and is what provides that tangy flavor we all love. Although phosphorous occurs in many natural foods such as meat, dairy, and nuts, too much of a good thing can be a bad thing. Excess phosphoric acid can lead to kidney disease, heart problems, muscle loss and osteoporosis. To make things worse, soda companies have been increasing the amount of phosphoric acid in sodas over the past decade. Conclusion: You need healthy vital organs for athletics.

Our discussion ended with the advice that she should begin to cut down, and ultimately cut out, diet sodas form her diet. I advised her that a good start to eating for endurance would be to eat real food that is somewhat similar in looks to its appearance in nature. And I’m pretty sure tangy, caramel colored, artificially sweetened drinks don’t occur in nature.