EUGENIZATION.

Today, as I trained my clients, not one session went by without talk about The Diet.

Yes, Michael Phelps‘ diet. I’ll refrain from passing judgment and try to talk about it from an athlete’s POV, as I feel news articles are sensationalizing Phelps - “What a freak.”

The question. “How can he eat all that and still look like this?”

The skinny bastard.

First, the info:

Now, the play by play:

Phelps is 6′4″, 195 lbs. He’s an Olympic-level athlete engaged in roughly 5 hours of rigorous swim training, as well as strength training. And he’s 23.

Using the Harris-Benedict Equation, we get a daily expenditure of 3971 Calories. Shows how limited prediction equations are.

Calculating Phelps’ BMR (Basal Metabolic Rate), we get 2089.65 Calories (per day). Add in the estimated expenditure from swimming and strength training (5100) and we come up with an estimated total of 7189.65 Calories per day.

That’s impressive, but it’s still not 8000-10000 Calories. So where do the extra thousand or so Calories go?

The X factors:

Lean mass - The prediction equations I used do not account for Phelps’ lean mass (read: muscle) which burns calories all on its own. You could argue that this accounts for an extra couple hundred Calories per day.

Thermogenesis - Not insignificantly, the food Phelps eats requires energy in order to be broken down and digested. Thermogenesis is estimated to contribute as much as 10% to metabolic rate. If Phelps really is downing 8000-10000 Calories a day, then his digestive system is working overtime to process that food. This could also throw a few hundred Calories into the mix.

Age - Phelps is young (and insulin sensitive). Metabolic rate slows as we age; conversely, we can expect metabolic rate to be higher in younger folks. Being insulin-sensitive helps drive those ingested calories to muscle cells (for use as energy) rather than to fat cells (to be stored for future use). So the food Phelps eats is used immediately (whereas ’tis not so in your average American Olympics viewer).

Reality - The realistic scenario is that Phelps isn’t really eating 8000 Calories everyday, and if we use food logs of athletes as evidence, this bears out. It’s possible that he eats 8000-10000 in a single day occasionally, but that his actual daily intake averages out somewhat lower (say, 6000 Calories or so). So, perhaps, one day he has 5500 Calories; the next 9798 Calories; the next, 6211 Calories, etc.

A final note: Some clients expressed shock and horror at the thought of an Olympic athlete eating pizza and pasta (especially after being told to avoid grains, etc.). My response: Phelps would not be physically capable of downing 8000-10000 Calories a day without the hunger-attenuating qualities of the carbs to aid him. It is precisely because he eats refined carbohydrates that he is able to put away that many calories.

Here’s an experiment: Get together 8000 Calories’ worth of sweet potatoes, avocados, chicken, eggs, and leafy greens. Put it in a big pile in front of you, set a timer to 24 hours, and make that pile disappear before the timer goes off.

Ready, set, go! Good luck.

(Actually, the timer should probably be set to 16-18 hours, since I’m sure Phelps sleeps a little.)

The moral? Phelps definitely expends tremendous amounts of energy daily, so much so that if he doesn’t eat an obscene volume of food, he actually loses weight. And in order to maintain that intake level, he resorts to eating from some admittedly crappy energy sources. Ironically, those same crappy foods enable him to eat the volume of food he requires.

O harmonious universe, how you taunt us!

Not to worry, all. Check back with Mr. Phelps in about 20 years or so - I suspect his caloric intake will be much different.