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Most of us know that being overweight is a health risk. It can increase your chances of getting several conditions, such as heart disease, cancer, diabetes, back pain and joint problems.
But if you’re just a few kilos overweight, is it really a problem? And how do you know if your weight has started to affect your health?
This may seem like a strange question. Of course we can all weigh ourselves on scales at home and find out our body weight in kilograms; but doctors are usually more interested in whether your weight is in the healthy range for your height, as well as where you are carrying the weight.
That’s because accurately measuring weight or, more importantly, your total body fat and where you tend to store it, can predict your risk of health problems such as heart disease and type 2 diabetes.
Body mass index (BMI)
Your BMI is calculated by dividing your weight (in kilograms) by your height (in metres squared). Your BMI - and whether you fall in the healthy range or not - may help predict whether your health is at risk. But BMI is not a perfect measure. Several factors, such as if you have a particularly high or low muscle mass, can mean that your BMI doesn’t properly represent your body fat. And health risks are not always estimated accurately by BMI values.
The risk of conditions such as heart disease, some cancers and diabetes increase in line with waist circumference. Current Australian guidelines state that to be in the healthy range, waist circumference should be less than 94cm in men and less than 80cm in women. But again, these measures are not accurate for everyone. For more on waist circumference, check out our article The new BMI: Can a piece of string determine your obesity risk?
Measuring waist circumference may be a better measure of health risk because it assesses where the weight is carried.
|Women||Men||Risk of health problems|
|80cm or more||94cm or more||Increased risk|
|88cm or more||102cm or more||High risk|
Please note: Different cut-offs may be appropriate depending on your ethnic background. If you’re from a non-European background, these waist circumference cut-offs may be too high and may underestimate your health risk. Sources: The Australian Institute of Health and Welfare and The Royal Australian College of General Practitioners.
Some people carry extra weight fairly evenly over their bodies, but most of us tend to carry it either around the hips and bottom (often referred to as pear-shaped) or around the belly (described as apple-shaped). You’d think that aside from the difference in appearance that body shape would have no particular significance. But it turns out that carrying weight around your middle is worse for your health.
Pear-shaped people have mostly subcutaneous fat - the type of fat that you can see and pinch because it sits just underneath your skin. Apple-shaped people also have subcutaneous fat - their fat sits more around their middles. But apples also tend to have a more sinister type of fat that cannot be felt because it deposits much deeper, around and between the abdominal organs. This so-called visceral fat is more dangerous to your health.
Visceral fat is also sometimes referred to as active fat. That’s because visceral fat cells don’t just store fat - they are busy secreting hormones and releasing harmful chemicals. These chemicals and hormones are involved in inflammation and insulin resistance (where the body becomes less responsive to insulin). They can also play a part in raising cholesterol levels.
Studies have found that having an increased amount of visceral fat (even if you’re not technically overweight according to your BMI) is associated with an increased risk of heart disease and type 2 diabetes. Some cancers, sleep apnoea and dementia have also been linked to this type of fat.
You can’t feel or see visceral fat, and even if your overall weight is in the healthy range according to your BMI, you can still have harmful visceral fat. So how would you know it was there?
Imaging tests such as MRI, CT and DEXA (dual-energy X-ray absorptiometry) scans can show the amount of fat you have, including visceral fat, and where it’s distributed in your body. But these scans can be expensive and some involve exposure to radiation.
Body fat-measuring scales are relatively cheap to buy and can give you an idea of your total body fat, but these scales are not always accurate and the results can vary significantly depending on how well hydrated you are. Also, they can’t reliably tell the difference between visceral and subcutaneous abdominal fat.
Accurately measuring weight can predict your risk of health problems such as heart disease and type 2 diabetes
Most doctors recommend simply measuring your waist to work out whether you are likely to have an unhealthy amount of visceral fat. A higher than normal waist circumference is a fairly reliable indicator that you have fat around your abdominal organs. Perhaps an even better measure that is gaining traction is waist circumference combined with a blood test that measures a type of fat called triglycerides.
Now for the good news. Healthy eating and exercise - strategies which have long been known to help people lose weight - also work for visceral fat.
Aerobic exercise, such as brisk walking, seems to be particularly helpful when it comes to tackling visceral fat - it may cut this type of fat even when there is minimal overall weight loss. And when it comes to diet, choosing the right foods and controlling food portions is important.
If you’re trying to lose weight but are not yet noticing the effects, don’t despair. The experts say that when you work off 5% of your body weight, you are likely to lose up to 25% of your visceral fat. So you may in fact be losing visceral fat and reaping unseen health benefits.
Overall, moving more and eating less will help shrink visceral fat. Ask your doctor for advice on weightloss and how best to measure your progress.
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