Friday, 17 October 2014

calorie and carb counting

Being a type 1 diabetic my overriding concern when out on a hike was how much carbohydrate (CHO) I’d need to keep me going, replace the glycogen in my body, and prevent hypoglycaemia (dangerously low blood sugar levels).

Over the weekend, among many of the conversations I had, one discussed weigh loss when on the trail. This got me thinking about the calorific value of the food I pack, and whether it met the demands of a day’s hiking.

The starting point was to establish my BMR (basal metabolic rate) this is an estimate of the minimum amount of calories needed to keep body functioning whilst at rest. I used the one on the myfitnesspal website here. Once I’d established that figure, I found an Activity Factor formula which is a basic multiplier of the BMR subject to the level of activity – see below.

Little/no exercise
BMR * 1.2
Light exercise
BMR * 1.375
Moderate exercise (3-5 days/wk)
BMR * 1.55
Very active (6-7 days/wk)
BMR * 1.725
Extra active (very active & physical job)
BMR * 1.9
A simple Excel spreadsheet did the trick. I’ve highlighted what I thought that would apply to time out hiking in the hills, and the formula determined that I would need 2,900 calories to maintain that level of activity. I then set about calculating how many calories I’d consumed listing them in the same spreadsheet. The outcome was a bit of an eye opener – I was short by circa 600 calories, that’s an approx. 20% shortfall. This probably is a factor in how I’ve managed to stay trim – which isn’t a bad thing. Whilst doing this exercise I also analysed the amount of CHO I consumed. This was also very revealing as it indicated that I need to increase the amount of CHO consumed at the end of the day, to top up the glycogen reserves, and to avoid an overnight slingshot hypo (never a good thing, and potentially life threatening).

In this instance, the shortfall was made up with a portion of chips and a few jars of cider. But going forward I’ll be re-introducing the stalwart Bird’s Instant Custard as a pudding with a cake bar or similar, not for the calories per se as I’d like to keep my figure, but for the necessary CHO loading.