I decided to give my Tanita Body Fat / Body Water Monitor a test. Lately my weight has been fluctuating between 117 and 121 within a 24 hour period which is highly suspicious. Normally I am pretty solid at 118 with a 18% body fat, it can be as low as 16% and as high at 19% depending on how much water I am drinking. The lowest I have ever gotten in the last two years is 14% at 113 pounds, normally a couple of weeks around marathon time.
If I am well hydrated the Tanita tells me my body fat is lower. So to put myself in a good mood I drink a liter or so of water, then weigh myself an hour later. My fat will be down, but a liter of water weighing 2.2 pounds my weight will be up, but that bothers me less.
Because I was born with an obsessive brain I often calculate the hypothetical performance benefit I will have running marathons at a lower weight. And with Boston 8 weeks away I might want to consider putting aside this bag of pretzels if it will make running easier and faster. So how do I know how much extra fat I am really carrying around and is my scale right? Ah ha! Today I had an appointment at Brooklyn College’s Kinesiology and Sports Medicine lab to be measured in their Bod Pod. The Bod Pod is a funky space pod looking contraption that one sits in wearing weight compression clothing, usually shorts for guys and shorts and sport bra for women or a speedo type swim suit. After a digital reading of one’s weight, you sit in the airlocked pod. It uses something called Air Displacement Plethysmography to determine the percent of fat, fat free mass, fat mass in pounds, fat free mass in pounds, body mass, body volume and body density. I found it cool to know that if my body was liquified I would fill 51 liters.
It was no surprise that I am classified as “lean with lower body fat levels than many people” The weight specifics on my scale was right, I weigh 118.517, 94.163 pounds of that are muscle, bone, organs and water or 79.5%; 24.354 pounds are fat which is 20.5.% Hum, that is more than my scale says, 24 pounds of fat? Yuk! To put it in perspective, to live, women need essential fat, 12% – 15% meaning I could weight as little as 109-112 and still function. But what is function? Does that mean I can still run 40-65 miles a week? Probably not for any length of time. But what if I lost 3 pounds or 2.5% body fat. I have read in many articles that for a 1 percent loss of body mass, primarily as body fat, there will be an approximate 1 percent increase in running speed. To put this in perspective, if you currently run a 10K at a pace of eight minutes (8:00) per mile, losing 5% of your excess body fat will improve your time to 7:36 per mile (8:00 x 0.05 = 24 seconds faster; 8:00 – 0:24 = 7:36). Consequently, you will run the 10K about 2.5 minutes faster, and your marathon about 11 minutes faster. That is something to think about.
I always want to run faster. I have no problem going out in blizzards, rain, cold, or heat to run. But, especially, after a 20 miler, my body is like a magnet being pulled into the bodega to get a pint of ice cream. Food is much harder to control. But maybe as an experiment, just for 8 weeks I can give it a try. 1% of fat = 1% faster? Well let’s see if I can put away the pretzels.