Let's talk about metabolism! Those of us who have struggled with our weight for any length of time have more than likely, at some point, blamed it on our metabolism.

But how many of us really understand what our metabolism is and how it works? Understanding how your metabolism affects your weight will be an effective tool in your efforts to lose weight.

Basal metabolism is defined as: the energy expended by the body while at rest to maintain normal body functions. Now, because energy calories, your basal metabolic rate is the number of calories burned by your body at rest. Muscle is very active tissue and has high energy, or calorie, requirements. Even when we are sleeping, our muscles are responsible for more than 25% of our energy (calorie) use.

An increase in muscle tissue causes a corresponding increase in our metabolic rate, and conversely, a decrease in muscle tissue causes a corresponding decrease in our metabolic rate. So, the more muscle mass we have on our bodies, the higher our metabolism will be, and therefore, the more calories we will burn; obviously, this is important in our efforts at weight loss.

Unfortunately, we lose half a pound of muscle every year after the age of 25.

This results in a half percent reduction in basal metabolic rate (BMR) every year. If our BMR decreases, our bodies are burning fewer calories and are less able to burn the food we consume as energy. This gradual loss of muscle tissue in sedentary adults leads to a 5 percent reduction in metabolic rate every decade of life. Obviously, this is closely related to the gradual increase in body fat that typically occurs as we get older.

When less energy is required for daily metabolic function, calories that were once used by muscle tissue will be stored as fat.

The only possible conclusion to draw from this information on the relationship between muscle and metabolism is that we must do everything we can to prevent the loss of muscle, and thereby the slowing of our metabolic rate if we want to avoid weight gain. The only way to do this is to implement a strength training routine into your regular exercise programme! In the next column, I will address some of the many other reasons for and benefits of strength training. But for today, let's continue talking about metabolism.

There are other important factors to consider when discussing metabolism and weight. Weight gain or loss comes down to a simple relationship: Calories in versus calories out. Calories in is the food and drink we put into our bodies, and calories out refers to the calories (energy) expended by the body through basic body functions and any activity or exercise that we do.

If we take in more calories than we burn, we will gain weight; if we burn more calories than we take in, we will lose weight! Sounds pretty simple when it's put like that, doesn't it? But let's take this a little further and see how it relates to metabolism.

Once again, basal metabolic rate is the number of calories used by your body to fuel the functions that keep you alive (e.g. blood circulation, digesting food, breathing, etc.). You can estimate your metabolic rate with the following Harris-Benedict formulas. First, you will need to calculate your height in centimetres (1 inch 2.54cm) and weight in kilograms (1 kg 2.2 lbs): For women: BMR 655 (9.6 x weight in kg) (1.8 x height in cm) - (4.7 x age in years) For men: BMR 66 (13.7 x weight in kg) (5 x height in cm) - (6.8 x age in years) Armed with your own BMR, you can then estimate your total daily energy expenditure (TDEE) and determine approximately how many calories your body needs to function on par each day. You can calculate your TDEE by multiplying your BMR by your activity multiplier from the chart below: Sedentary:BMR x 1.2 -- little or no exercise, desk job Lightly active:BMR x 1.375 -- light exercise/sports 1-3 days/wk Moderately active:BMR x 1.55 -- moderate exercise/sports 3-5 days/wk Very active:BMR x 1.725-hard exercise/sports 6-7 days/wk Extremely active:BMR x 1.9 -- hard daily exercise/sports & physical job or twice daily training, for marathon or contest With this new knowledge about your total daily energy needs, you are ready to work on losing weight. Let's go back to how metabolism relates to weight loss.

Your basal metabolic rate is the absolute minimum number of calories your body needs to function.

With that, you have now calculated how many calories your body needs on a daily basis given the amount of activity or exercise you get. This takes us back to the calories in versus calories out equation. Keep a record for a few days of everything you eat, in what quantities, and the calorie content; then compare this to your total daily energy expenditure.

If you have a weight problem, you are either eating too many calories, not doing enough exercise or, just to confuse you, you may be eating too few calories. Consuming too few calories will cause your body to slow down its metabolism in order to conserve energy. We'll go into more detail on that in a future article.

Here are the basics: Add strength training to your exercise programme to speed up your metabolism.

Calculate your basal metabolic rate and total daily energy expenditure (including your new strength programme) using the equations above.

Adjust your caloric intake according to your goal. To lose weight, you need to create a calorie deficit by reducing calories slightly below your maintenance level and/or increasing your energy expenditure through exercise. Reducing calories by 15 to 20% below TDEE is a good place to start.

I hope that this information on metabolism and how you can make it work for you will help you on your journey to becoming Body Wise.