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Why do we get fat?

Why do we get fat?

The answer is simple really, at least that’s what we are told: we get fat because we eat too much and exercise too little. In other words, it is all about gluttony and sloth!

A local doctor suggested to me recently that “all they (the overweight) need is a poke in the ribs” – no wonder we are weighed down by guilt and self-doubt.  People who have struggled with weight for years know that fat gain and weight loss are far from simple; to suggest that all they need is a bit of resolve and willpower is insulting at best. I know from personal experience and from the people I see that dieters have the strongest of willpowers – willpower, unfortunately, will never win when biology and the world we live in fight it at every turn!

So what makes us fat and why is weight loss so difficult?

Our genes work against us

You can blame your genes, but only to a certain extent. It is estimated that 60 per cent of us are predisposed to gain fat easily. This is not surprising considering fat storage along with a strong drive to eat were essential for survival in all but recent times. In today’s world of food abundance, however, these genes work against us. The drive to eat plus an almost limitless capacity to store fat are seeing obesity and associated health consequences rising to alarming levels. This is not to say that you should give up – while genes may predispose you, your lifestyle choices will determine how they are expressed.

We have forgotten the true purpose of eating

In a world where thousands of food products compete for market share, taste, convenience, fashion and cost now replace nutrition as the main reasons for food choice. The true function of food, ie. as a provider of essential nutrients, has largely been forgotten. This is reinforced by TV programmes such as MasterChef, where judges view being ‘healthy’ as synonymous with ‘won’t taste good’. Participants have to downplay any nutritional advantage their products might have!

Our food supply has dramatically changed

In the last 100 years, technology has completely changed our food supply. While this has brought many positives (safer milk, canned and frozen fruit and vegetables, commercial bread etc), it has also led to increasing development and consumption of nutrient-poor, high-energy foods. As companies manipulate texture and taste to provide easier and more pleasurable eating, the nutritious core foods that sustained us for millennia are increasingly side-lined. Nutritionally useful components of food (such as the bran and germ from wheat) are often removed while layer upon layer of fat, sugar and/or salt are added to increase shelf life and hook us in. All this increases the number of kilojoules per unit weight and ‘dilutes’ the useful nutrients found in the other ingredients. Our unchanged hunter-gatherer genes drive us to eat these energy-dense/nutrient-poor processed products then go into overdrive storing unused kilojoules as fat. In a nano-second of time in the scale of history, we have achieved an unusual situation: people who are overfed (consuming too many kilojoules) yet undernourished at the same time.

Muesli bars are a good example here.

Rolled oats (healthy) have morphed into rolled oat bars (oats and dried fruit glued together with eggs and a little honey). These in turn have evolved into the muesli bars that fill supermarket shelves today and which are little more than confectionery, ie. a smattering of oats overwhelmed with sugar, chocolate and butter.

High fat, high sugar, high salt food is addictive

David Kessler, in his book The end of overeating, explains that certain foods stimulate the brain in the same way as other addictive products such as cocaine and tobacco.

“Foods with hyper-palatable combinations of salt, sugar and fat have the capacity to rewire our brains, driving us to seek more and more of these products. The more potent and multisensory foods become, the greater the rewards they may offer and the more we learn to work for them… Eating delicious foods tells the body to eat more of these delicious foods.”

Profit-driven food companies naturally take advantage of this by carefully engineering food so that we are driven to seek more. Once we are hooked onto blends of fat, salt and sugar, it is very hard to resist their pull.

I have just scraped the tip of the iceberg here… more to come next time!


Bronwen King is a NZ-registered nutritionist and qualified chef, and regular contributor to Healthy Food Guide magazine. She specialises in population health nutrition and weight management and currently manages Appetite for Life, a primary care-based healthy lifestyle and weight management programme in Canterbury. She enjoys everything about food! Check out Bronwen's personal blog, www.eatlosewin.com.

First published: Aug 2012
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