GILES WARRINGTON FIT FOR LIFEGetting your energy levels right for you
TO SUPPORT normal physiological function and sustain everyday activity, the body requires energy which is consumed as part of your daily diet in the form of carbohydrate, fat and protein.
Energy, both in terms of intake and expenditure, is measured in calories (kcal). Energy balance is like a set of scales - if your daily energy intake, in terms of calories consumed, is greater than total daily energy expenditure, then your body weight will increase. In contrast, if your daily energy expenditure is greater than your energy intake, then your body weight will fall.
Sustaining vital functions
Regardless of daily activity levels, a minimal amount of energy is required to sustain your body's vital functions in a resting state. This is referred to as "resting energy expenditure".
A typical resting energy expenditure would be somewhere in the region of 1,200-1,500kcal per day and will be determined by a number of factors such as size, muscle mass and also fitness levels.
Generally fitter, more active individuals have a higher resting energy expenditure, meaning they burn more calories at rest.
Resting energy expenditure
For the average healthy person, the resting energy expenditure accounts for about 60-75 per cent of total daily energy expenditure, with the balance being made up from the heat produced from eating and digesting food (about 10 per cent) and daily physical activity (about 15-30 per cent).
In order to maintain energy balance (ie, maintain your current body weight), the typical guidelines for daily energy intake would recommend that the average size female and male would consume about 2,100 and 2,800kcal per day respectively. However, this may vary somewhat depending on your daily activity levels.
The more physical activity performed during the day, the greater the energy demand. Despite this, evidence would suggest that about 75 per cent of the average person's day is spent performing activities requiring only low energy expenditure.
For most people, energy expenditure rarely increases noticeably above resting levels for prolonged periods, with walking being the most common physical activity undertaken.
Extreme levels
At the opposite end of the physical activity spectrum, elite cyclists competing in the Tour de France may expend as much as 7,000kcal per day. Greater still, polar explorers man-hauling 485lb sleds have been shown to expend over 11,000kcal per day.
The sheer volume of food required to replace such an extreme level of energy expenditure would be nigh on impossible to consume on a daily basis (let alone carry on their sledges).
It is, therefore, not surprising to find that these polar ultra-marathons often result in extreme weight loss. In one case, the famous explorer Ranulph Fiennes is reported to have lost a third of his normal body weight (30kg) over a 90-day period when traversing Antarctica, a distance of some 2,170 km.
Everyday activity
More common everyday, recreational and sporting activities will also lead to noticeable levels of energy expenditure. The energy cost of everyday tasks are varied and will be dependent on the intensity and duration of the particular activity.
The average 70kg individual exercising for 30 minutes would burn about 200kcal walking at 7km/h; expend about 350kcal jogging at 10km/h and about 270kcal steady swimming. Everyday chores such as cutting the grass and digging for the same 30 minutes would lead to an energy expenditure of about 240kcal, whereas washing the car or dusting would burn in the region of 150kcal.
You may be surprised to learn that you actually burn more calories playing a round of golf than playing squash for 40 minutes! This is due to the fact that although the intensity of squash is far greater, the typical round of golf would take about five hours to complete involving walking about 8-9km as well as carrying a bag or pulling a trolley over an undulating terrain.
However, some of the physical benefits gained from the "good walk spoiled" might be undone if you disappear to the 19th hole.