Many of us will have ushered in the New Year with the best of intentions, and may well be reigning back on our intake of food or upping our exercise output in an effort to lighten our load. Those whose focus is on shedding surplus weight are quite likely to be monitoring their progress with regular weigh-ins on the gym or bathroom scales. While this may be the most familiar form of measuring body mass, it unfortunately tells us nothing about whether any purged poundage has been in the form of fat, or some other bodily component such as glycogen (a carbohydrate storage fuel), muscle or fluid. Also, new research suggests that its not just how much fat is lost, but from where on the body it is shed that determines the implications this has for health. It does seem the usefulness of assessing our size by stepping on the scales is in the balance.

With rates of overweight and obesity burgeoning as they are, more and more of us are feeling the need to attain and maintain a healthy weight. In recent years, ideal weight recommendations have generally been based on what is known as the body mass index (BMI) - calculated by dividing an individual’s weight in kilograms by the square of their height in metres. Generally, BMIs of between 20 and 25 are taken as being ‘healthy’. A major failing of the BMI, however, is that it tells us nothing about body make-up. It is possible, for instance, for a powerfully-built individual to turn up a relatively elevated BMI, despite carrying very little in the way of excess fat. The BMI simply does not discern whether any additional bulk is the result of a surfeit of brawn, or blubber.

Another deficiency of the BMI is that it does not assess body shape. This is important because there is a good deal of evidence that fat sequestered around the middle of the body (so-called abdominal fat) has a more detrimental effect on health than fat found elsewhere in the body. A recent study published in the American Journal of Clinical Nutrition found that a generous waist measurement (known as ‘abdominal obesity’) is an important risk factor for biochemical imbalances (such as elevated blood levels of sugar, insulin and cholesterol) that are hallmarks of a condition known as insulin resistance syndrome (IRS). In addition to its relationship with growing girth, IRS is believed to be a potent underlying factor in both heart disease and diabetes.

So important is this concept of abdominal obesity believed to be, that the measuring of waist circumference is increasingly being seen as a highly useful screening tool for individuals at risk of IRS and the health issues associated with it. Because any reduction in waist size is likely to bring greater health benefits than more generalised reduction in weight, it seems the tape measure represents a low-tech, cheap and practical way to assess weight loss progress. I’m away for a week, but in my next column I’ll be exploring the dietary strategies that are most likely to bring success in an assault on abdominal obesity. In the meantime, it’s worth bearing in mind that loosening waistbands and the ability to ratchet up your belt a notch or two are very good signs that you’re winning the battle of the bulge. For those who would prefer a more objective measurement of waist size, I recommend having it taped.

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