And Now for the Science…

My lovely caring Wife has been a little worried about how I’m going to sustain myself on the MdS, and fears that the minimum calorie amount of 14,000kcal that runners are allowed to carry is set with an 8 stone racing snake in mind. To make sure that I have planned to carry enough food; she asked her friend Alison, who is a nutritionist/dietician, to do some research and try to calculate how much a guy my size should be eating to survive such a race. Alison knew exactly how to work it out and provided the following formula to calculate my Basal Metabolic Rate, which gives my body’s calorific requirement for a 24hr period at rest:

Men:           BMR = 66+(13.7 x weight in kg)+(5 x height in cm)-(6.8 x age)

Women:     BMR = 655+(9.6 x weight in kg)+(1.8 x height in cm)-(4.7 x age)

So my        BMR = 66+(13.7x87)+(5x185)-(6.8x35)

                   BMR = 66+(1191.9)+(925)-(238)

                   BMR = 1944.9 kcals/day

Now clearly I am not going to be ‘at rest’ over this 6 days, so the kcal amount must be adjusted. That is where the Harris Benedict Formula comes in and is applied to the base BMR in accordance with your level of activity:

•                     Sedentary (little or no exercise):                                      BMR x 1.2

•                     Lightly active (light exercise 1-3 days/week):                  BMR x 1.375

•                     Moderate active (moderate exercise 3-5 days/week):    BMR x 1.55

•                     Very active (hard exercise 6-7 days a week):                 BMR x 1.725

•                     Extra active (very hard exercise or 2x training):              BMR x 1.9

So I’m guessing I’ll be extra active? Six days of 1944.9kcals multiplied by 1.9 gives me a total energy requirement of 22,172kcal. Michelle was quite right, but she needn’t have worried. I collected all of my food and race equipment together last night, catalogued and weighed it all with a complete menu of what I thought I would like to take. On adding up the calories; I found that the total came out at over 27,000kcals! This resulted in a pack that weighed in at 12.5kg. Dumping snack and supplement items to the tune of 3,000kcals brought the pack weight down to 10.5kgs.

Almost everything, less warm kit, goggles and hexi+stove

Just carrying an extra 2kg would mean burning several thousand more calories over the course of the race and is highly likely to be inefficient. Some, including Iain, take the view that it is actually more prudent to deliberately go into calorie deficit on such a race. It is certainly the only option for challenges such as polar expeditions, where it costs far more energy to pull food than can ever be recovered from it. MdS will not be that extreme, but I can certainly afford to burn up a few percent of body fat to save me carrying those extra kilos. I must now decide how far I want to go in cutting my rations, as I have 6,000kcals to play with, possibly worth around 3kg.