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Friday, July 19, 2024

How should we be dieting?

Duane Mellor and Cathy Knight-Agarwal |

Diet guidelines always come under a lot of fire. They have been accused of not being based on evidence, not being environmentally sustainable and being out of touch with nutritional science. And as has been shown time and again they fail to change people’s eating habits.

The time has come for us to rethink the purpose of dietary guidelines, what they contain and how they deliver their message.

As part of this, we need to think about how the public views these guidelines (and other health guidelines) so they become relevant. Hopefully, then people will be more likely to follow them.

If we don’t, we risk investing more research time and taxpayers’ dollars into producing documents many people seem to dismiss.

Are government dietary guidelines just too hard to meet?

There is good evidence from dietary surveys that for example only 4% of Australians meet the recommendations made in dietary guidelines, particularly when it comes to eating enough vegetables.

Dietary guidelines come under a lot of fire. They have been accused of not being based on evidence, and being out of touch with nutritional science.

So, should we make dietary guidelines easier or at least have more achievable targets so we don’t feel we are constantly “failing”? For instance, rather than pushing just the “5+2” a day (five serves of vegetables and two of fruit a day) as the only goal worth aiming for, we should start with a positive message encouraging people to eat more fruit and vegetables than they’re eating now. We could do this by breaking this down into achievable steps, for instance, recommending one more piece of fruit today and two more tomorrow.

read more: Enough with the Fear of Fat

Nutrition “experts” also often say “everything in moderation” when recommending a balanced or healthy diet. This may have merits. But clearly, some people cannot limit, restrict or consume high-sugar and high-fat foods in moderation, despite guidelines suggesting you should only eat them sometimes and in small amounts. In general, more than one-third of our energy intake comes from these so-called discretionary foods.

In any case, what does an occasional piece of chocolate cake mean? Is it once a week, a month or a year? How big a slice?

Perhaps we need to enjoy these foods, not feel guilty about eating them or seeing them as a treat, instead slotting them into our routines in smaller amounts and less frequently.

Meanwhile, when it comes to avoiding discretionary foods, our brains set us up for failure. Our brains are hardwired to seek out high fat, high sugar food and drink. This stimulates production of dopamine, the “happy hormone” that helps control the brain’s reward and pleasure centres. Put simply, we like the way it feels when we eat these foods so want to come back for more.

Are we addicted to some foods?

In 2014-15, a staggering 63% of Australians aged 18 years or more were overweight or obese, about standard for anglo-western countries. This suggests our addiction to high-fat, high-sugar foods.

Like addictions to nicotine and alcohol, should health professionals say moderation fails and abstinence of some foods is the only way? Or is dietary intake far more complicated?

Some people do exceptionally well abstaining, for instance media personality Peter FitzSimons writes about his year without sugar and alcohol.

Read more: How do you get kids to eat vegetables?

But some suggest restrictive dieting can lead to binge eating, increased weight over time and eating disorders. Some people can, and maybe even should, include a moderate amount of discretionary foods in their diet, without feeling guilty, to reduce the likelihood of developing an “unhealthy relationship” with food.

So, being flexible (or strict) with diet may be the ideal for some but catastrophic for others.

Is it food or nutrients?

In Australia, the first government dietary guidelines appeared in the 1980s as a 20-page booklet. In its most recent version in 2013, the National Health and Medical Research Council filtered 55,000 pieces of evidence and documents to settle on more than 1,100 in a 210 page technical report.

As well as the complexity of the evidence base, the type of recommendations in dietary guidelines have changed over the years. Once, dietary guidelines focused on nutrients we should eat or avoid, for instance the type of fat or sugar.

But our attitude to individual nutrients changes. For instance, the 1980s fat-heart-health idea that high fat intake was bad for your heart has been widely questioned; recently sugar has been labeled as public enemy number one.

We are still recommended to eat or avoid some nutrients today, such as lower fat dairy, a point critics challenge in light of recent evidence.

We should continue this shift away from nutrients to foods. After all, we don’t eat single nutrients; we eat foods.

Nutrition “experts” also often say “everything in moderation” when recommending a balanced or healthy diet. This may have merits. But clearly, some people cannot limit, restrict or consume high-sugar and high-fat foods in moderation

This shift should really go much further. Rather than mainly focusing on avoiding discretionary foods high in added fat and sugar, we should focus more on the positive message of recommending non-discretionary food. The World Health Organization calls them minimally processed foods, which include vegetables and fruit along with dairy produce, lean meat, fish and alternatives (pulses and eggs) and wholegrain cereals.

Ultimately, we need to shift the focus to look at dietary or food patterns, as seen in the recent Brazilian and to a certain extent the US dietary guidelines. For example, the guidelines from Brazil include concepts of enjoying shopping, sharing cooking and being cautious about advertising, going far beyond stating nutrient goals.

This should, ultimately, also be the future for dietary guidelines. This is not only because we eat foods not nutrients, but because food is culturally more important than the chemicals it contains.

What (and who) are dietary guidelines really for?

We also need to be clear what and who dietary guidelines are for.

Do western dietary guidelines aim, as their name suggests, for a healthy diet for all or a guide to prevent weight gain? A simple review of the technical document accompanying the guidelines finds more than 100 references to “obesity”, suggesting the latter. In fact, the word “obesity” appears four times more often than the words “underweight” and “malnourished” combined.

Read more: Genetic Heart Disease Risk Eased by Healthy Habits, Study Finds

Dietary guidelines are meant for the general public, therefore should not be aiming to treat disease, only looking to reduce the risk of developing illness.

Rather than just focusing on obesity, we should really try and focus on dietary approaches to maintaining health for an aging population. For instance, we could provide nutritional information aimed at maintaining muscle mass as people age, a significant problem in the elderly and closely linked to ill health and death.

As we rethink the purpose of dietary guidelines, what they contain and how they deliver their message, perhaps we should ask ourselves whether people ate more healthily before dietary guidelines were introduced and if so why.


Duane Mellor, clinically as a dietitian, has extensively worked in the fields of diabetes and obesity with a special interest in nutrition and pregnancy. He completed his Ph.D. investigating the effects of polyphenol-rich chocolate on cardiovascular risk factors in Type 2 Diabetes. Cathy Knight-Agarwal is a clinical dietitian by profession and has worked at the University of Canberra for the last decade as a lecturer for the discipline of Nutrition and Dietetics. She recently completed her Ph.D. in the area of maternal obesity prevention. The views expressed in this article are the authors’ own and do not necessarily reflect Global Village Space’s editorial policy. This piece was first published in The Conversation. It has been reprinted with permission.