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What’s BMI Got To Do With It?

Do you think you’re healthy? Phillipa Bredenkamp, a dietician at Mindful Eating (www.mindfuleating.co.za), debunks the issues weighing on our minds.

For some, health and weight go hand in hand. However, many of our ideas about weight and nutrition are based on myths and, sometimes, what’s generally believed to be good is bad and what’s thought to be bad is actually good for you. Bredenkamp sets the record straight.

What is BMI and what relationship does it have with one’s health and nutrition?

BMI stands for Body Mass Index. It’s calculated by taking your weight in kgs and dividing it by the square of your height, in metres (kg/m2). It’s a convenient measure used to screen for obesity, however it does have some limitations.

Can people exercise, have a healthy diet and yet still have a high BMI?

Yes, this happens and is one of the major limitation of BMI, as it does not take a person’s muscle mass into account. If you calculated the BMI of a body builder, they would likely have a BMI above 30kg/m2, which would be classified as obese. However, by simply looking at the body builder’s physique, you can see this is not true.

Are BMI and weight a good measure of health?

These, together with waist circumference – which measures the amount of abdominal fat a person has – would give a better indication of disease risk than BMI and weight alone.

Will eating a low-fat diet necessarily make someone lose fat?

Losing fat requires eating less overall calories, not just less fat.

What foods have always been considered bad, but are actually good for health and nutrition?

The most common ones are bananas and carbohydrates. Many people have the idea that bananas make you fat. A medium banana has the same nutrition as a medium apple or pear, but, for some reason, people always think they must avoid bananas. Bananas are rich in potassium and can help lower blood pressure. With carbohydrates, people believe they make you fat and you should cut them out completely. However, when people cut them out, they often end up quite depressed, moody, craving sweet things and low in energy, as carbs can increase serotonin. We advise a lower carbohydrate intake, but not a low or no-carb diet. Complex carbs like brown rice, butternut, and corn can form part of a healthy, weight-loss eating plan. It’s refined carbs like white bread, cakes and white pizza dough that we should avoid.

Which good fats should one be incorporating into their diets to keep a balanced BMI?

Fats are tricky when it comes to maintaining a normal BMI. You need good fats like nuts seeds, avo, olives, olive oil and canola oil in your diet, but too many of them will result in weight gain.

Is the notion that one can be overweight but fit, true?

This is commonly known in the media as ‘fat but fit’ and refers to people who have excess weight, but are thought to be metabolically healthy – and thus do not experience adverse health effects from their excess weight. However, a new study published by the European Heart Journal, has dispelled this as a myth. The study found that being overweight or obese increased a person’s risk of heart disease by 28%, despite their fitness level, compared to those with a normal weight.

Does metabolism play a role in a BMI reading?

Indirectly, as with a very fast metabolism, one’s weight will be lower, therefore, their BMI will be lower.

What metabolic markers should underweight or overweight people look out for? 

It’s different for each person, but for overweight people, I start with the basic like a full cholesterol profile, thyroid and blood glucose. For underweight people, I’d likely test for nutritional deficiencies like iron and vitamin B.