Body & Fitness

Are you a TOFI: Thin on the outside, fat on the inside?

New science shows being overweight need not mean being unhealthy – and some people with normal body weight can be dangerously “fat on the inside”.

Science has found that someone’s weight is not always an indicator of their health and fitness.

In nutrition research, it’s called the “TOFI” theory – thin on the outside, fat on the inside – which means even an apparently lean individual can store their body fat in the abdomen around their vital organs instead of the safer option – in the subcutaneous tissue, under the skin.

It’s that internal visceral fat that infiltrates the liver and other key organs and is associated with type 2 diabetes.

Scientists now know that people of Asian and Indian ethnicity are susceptible to diabetes at a younger age and at a lower weight than Pacific people and Europeans. For the same weight and height, for example, Indian women have 10 per cent more body fat than Pacific women.

But why?

In the notoriously complex field of nutrition and metabolic health, it’s one of the most baffling questions of all, but a vitally important one that has ramifications for us all as we get older and fatter.

The team at Auckland University’s Human Nutrition Unit are looking for the answers. What they’ve learned is that it’s impossible to predict from size alone who will be at increased risk of diabetes and who will not.

A healthy BMI (body mass index) may be completely irrelevant to an individual’s health risks.

University of Otago nutrition researcher Lisa Te Morenga says around a quarter of adults have a fatty liver without knowing it, and now even children are starting to develop the condition. The best indicator of visceral fat is waist circumference – it should be half your height or less.

“I often worry now we are becoming so obsessed with fatness we are not seeing the wood for the trees,” says Te Morenga. “Perhaps we rely too heavily on obesity or overweight as a trigger to investigation when you can be just as unhealthy with a normal body weight.”

In terms of where people store fat, obviously genetics are important. The challenge for the scientists at the Human Nutrition Unit is to work out how food can be adapted to reduce organ-hugging, visceral fat and increase blood sugar control.

University of Otago nutrition researcher Lisa Te Morenga.

Te Morenga is exploring how wholegrain foods influence health.

She says many foods that seem healthy, really aren’t: “Sushi is high in refined carbohydrates, most sandwiches are in white bread like panini and even soup usually comes with a refined white roll.”

Bread is often served in thick chunks – not necessarily bad, “but there’s a lot of it and it’s very easy to eat too much”.

Someone with diabetes or pre-diabetes is better to limit bread to two (small) serves at lunchtime and fill up with vegetables, fruits and lean protein.

Te Morenga says people should try to focus more on eating more of the right foods, rather than concentrating on weight loss alone.

Her work made international headlines in 2011 after she published a study showing women lost more weight and improved their metabolic risk on a high-protein, high-fibre diet, rather than a standard low-fat, high-carb regime.

Find out more about the research underway at the Human Nutrition Unit, also how to improve your gut health – in North & South Investigates’ special issue The New Science of Mood, Food + Wellbeing, on sale now. North & South’s writers also investigate the latest cancer treatments, find out why being anxious may make you a better person, scrutinise the vitamin industry – and more.

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