Sugar vs fat: Will the real demon please stand up?
If you’re confused about whether to cut the fat or tame your taste for sugar, we’re not surprised. Paula Goodyer sorts fat, er fact, from fiction.
Many of us blame sugar for our health woes. It loads our diets with excess kilojoules and our food with extra sweetness, making it easy to overeat. Yes, sugar’s already in the sin bin, but over the past few years its reputation has sunk to a new low. Its critics have branded it both dietary public enemy number one and the major cause of obesity.
Meanwhile, saturated fat has been excused from the naughty corner and is now sporting a ‘health halo’. News headlines claim that sat fat is less of a risk factor for heart disease and obesity than we’ve been led to believe, but you may have also heard that it’s so good for us, we should be sautéing our vegetables in butter or pork fat! At least, that’s the message you’re likely to take away from media reports claiming that saturated fat is healthy.
The ‘sugar is bad; saturated fat is good’ debate has been fuelled partly by conflicting expert views, and on top of this, the rise and rise of the non-expert. Bloggers, writers and chefs, many of whom have little or no background in nutrition science, are voicing their opinions and adding to the confusion. All of a sudden, a sprinkle of sugar on porridge is setting us on the path to obesity, while butter, a former bad guy, is widely promoted as a natural healthy fat. But is sugar really the major threat to our health it’s made out to be? And should we really be eating more saturated fat?
The sweet truth
Let’s start with sugar, and a brief look at the way scientific research is driving the idea that the sweet stuff is somehow toxic. Understanding this complex topic demands a little background information on the natural sugar fructose. So what exactly is it? And how did it get such a bad name?
You may know that fructose is fruit sugar, but it also makes up 50 per cent of cane sugar (aka table sugar or sucrose) — Australia’s most popular sweetener. Glucose makes up the remaining 50 per cent, but it’s the fructose that makes cane sugar so sweet.
Most of us didn’t give fructose a second thought until paediatric endocrinologist Dr Robert Lustig labelled sugar a ‘poison’.
In 2012, this American doctor claimed that eating large amounts of fructose promotes weight gain. How? It increases both kilojoules and insulin resistance, a disorder that not only makes it easier to gain weight, but also ramps up the risk of type 2 diabetes.
And that’s not all, according to Lustig, who also said that consuming too much fructose leads to fatty-liver disease.
The problem with cane sugar is that its fructose half behaves differently from its glucose half. When we eat food that contains cane sugar, its glucose is taken up by several different bodily organs (including the muscles and brain), but its fructose goes only to the liver. Lustig says that when the liver has to process an overload of fructose, problems such as fatty-liver disease and insulin resistance can result.
Although the evidence that excessive fructose consumption promotes insulin resistance and fatty-liver disease is convincing, fructose isn’t the main cause of obesity, says Professor Joseph Proietto from The University of Melbourne, who’s also a past president of the Australian and New Zealand Obesity Society (ANZOS). What’s more, he adds, it’s certainly no reason to drop fruit from your diet.
“With fruit, you’re eating important nutrients and fibre, not just fructose,” he says. “The problem with fructose occurs when you consume it in large amounts in the form of foods such as soft drink. “But even then, sugar alone doesn’t make people obese. The real cause of the obesity epidemic is the combination of genetic influence and an environment that offers too much high-kilojoule food and little need to be physically active. In such an environment, genetically lean people will gain weight, but they won’t become obese.”
The fundamental problem is that human evolution hasn’t caught up with the way we find food today. Sourcing a meal now demands just a quick drive to the shops on our way home from sitting at a desk all day — a far cry from the hours our ancestors spent hunting for wild game or trudging across the savannah in search of edible plants.
“On an evolutionary timeline, it’s only in the last few minutes that we’ve had easy access to so much food,” explains Proietto. “The human body is still meant to work very hard to find food, so when we expend so little energy to find so much food, we become overweight or obese.”
Look beyond sugary foods
Shifting the blame for obesity onto sugar just distracts us from other factors that contribute to weight gain, cautions Proietto. His long list of offenders includes sedentary lifestyles, lack of sleep and disruptions to our circadian rhythms (which can be caused by exposure to excess light at night and even certain gut microbes). Other suspects include health problems, such as thyroid disorders, and some prescription drugs, such as medication for type 2 diabetes and some mental illnesses.
Scapegoating sugar also makes it too easy to overlook other eating (and drinking) habits that can lead to weight gain, adds Accredited Practising Dietitian Catherine Saxelby, author of Catherine Saxelby’s Complete Food and Nutrition Companion.
“A lot of people eat too many foods and soft drinks with excess added sugar. However, sugar alone isn’t to blame — the real culprit is the combination of sugar, fat and refined carbohydrates you find in processed foods,” explains Saxelby.
“When people tell me they’ve lost weight because they’ve quit sugar, I usually find that they’ve cut out foods such as sugary muffins and desserts, which also contain bad fats and carbs, and the kilojoules that come with them,” says Saxelby. “For example, if you slash five teaspoons (20g) of sugar from your diet, you lose 320kJ (77cal). But if you cut out two glazed cinnamon doughnuts, you remove roughly the same amount of sugar, along with 26g of fat, 24g of refined carbohydrate and 1900kJ (455cal).”
As for alcohol, “some young people are drinking up to 12 standard drinks in one session, and that’s like eating 12 slices of bread,” Saxelby cautions. “Then there are ultra-processed foods such as chips, for example. These contain no added sugar, but people eat too many of them.”
Be sweet smart
Although Saxelby believes we should reduce the added sugar in our diets, she’s not keen on simply replacing it with an alternative sweetener, such as rice-malt syrup or stevia. In her view, that would only feed our taste for highly sweetened foods.
A smarter approach, she says, is to sprinkle less sugar and take control of how often it sweetens your food. She also recommends eating more wholefoods you’ve prepared yourself, and if you need a touch of sweetness, say, in your breakfast bowl, add fresh fruit, which also provides extra fibre.
Saxelby also suggests buying natural yoghurt instead of flavoured varieties. If you find the natural stuff too acidic, don’t be discouraged. Shop around and you’ll find a product with a milder taste. Still want a sweeter yoghurt? Drizzle it with a small amount of honey or top it with sweet berries.
The sat fat facts
Now let’s explore the idea that we should go back to eating saturated fat. It’s true that some recent research shows that reducing sat fat doesn’t reduce levels of heart disease — but does this mean fat is no longer the threat to our health we once thought?
This controversial concept is creating plenty of buzz in the media, but it’s not that simple, says Jennie Brand-Miller, Professor of Human Nutrition at The University of Sydney. (Brand-Miller is also a pioneering researcher into insulin resistance and a co-author of The World’s Best Diet.)
Basically, the health message to limit saturated fat for our heart’s sake backfired. Yes, many people reduced their intake of saturated fat, but they also started to eat more refined carbohydrates, and these aren’t heart healthy either, explains Brand-Miller.
“I think experts now recognise that telling people to avoid saturated fat for their heart’s sake, and to limit all fats to prevent weight gain, was a too-simple strategy that failed,” she adds. “Australians did reduce their total fat intake, but they often replaced the fat with carbohydrates that score high on the glycaemic index (GI). These include rice, breads, potatoes and breakfast cereals — carbs that have since been linked to higher risks of type 2 diabetes, cardiovascular disease and some cancers,” says Brand-Miller.
“Unfortunately, the message made people fat phobic, and the term ‘fat free’ suddenly became synonymous with good health.”
Reach for the right fats
Our new understanding, says Brand-Miller, is that it makes more sense to assess foods on their merits as a whole — not to judge them by their fat or sugar content alone.
“Focusing on single nutrients and blaming one or another for our [health] woes is a problematic approach that some people call nutritionism,” she says. “I think most nutritionists now appreciate that our diets are not made up of macronutrients, such as fat or carbohydrates, but of whole foods. “Nuts, for instance, contain more fat than unhealthy chips do. And dried fruit is full of sugar, but it also provides fibre and valuable nutrients.” The latest Australian Dietary Guidelines recognise this, advising us to either eat or limit certain foods.
Even fat isn’t necessarily a culprit in weight gain, at least not as part of a diet that includes healthy fats, says Brand-Miller. “Studies show that compared with low-fat diets, Mediterranean-style diets (which are high in ‘good’ fats, such as nuts and olive oil) promote better weight control and lower risks of heart disease and stroke,” she explains.
In Brand-Miller’s opinion, the low-fat message for weight control has been unhelpful. She thinks we should stop counting the number of kilojoules and grams of fat or carbohydrates in food. We need to start choosing foods on the strength of their ability to keep us satisfied and feeling full. In other words, opt for lean protein-rich foods, and include plant sources, such as nuts, beans, lentils and chickpeas.
We should also swap high-GI carbohydrates for their low-GI counterparts. Instead of flaked and puffed breakfast cereals, eat traditional oats. Replace breads made of finely ground flour with dense wholegrain breads that have visible grains and seeds. Barley and quinoa are also good options when you’re trying to add low-GI carbs to your diet.
Keep sat fat in check
So if fat isn’t the enemy, is saturated fat off the hook? As Brand-Miller says, “saturated fat is the single most important player in increasing levels of ‘bad’ LDL cholesterol, which is a precursor of heightened rates of heart disease and related deaths”.
“In my opinion, we should keep saturated fats to less than 10 per cent of total kilojoules,” says Brand-Miller. “This means choosing reduced-fat dairy foods and lean meats as well as limiting the usual suspects: sausages, salami, meat pies, chips, cakes and biscuits.”
“My advice for people who want to lose weight? Cut out highly processed foods and alcohol, but keep eating foods that provide healthy fats,” says Saxelby. ‘Good’ fats, such as those in nuts, avocado and olive oil, actually lower cholesterol levels and stop blood from clotting, thereby reducing our risk of heart disease. In addition, the healthy omega-3 fatty acids in oily fish, chia and flaxseeds are linked to better brain function and mood, as well as a decreased risk of diabetes.
“My approach is not to worry too much about avoiding full-fat yoghurts, for instance. They’re not that different from reduced-fat yoghurts, and the full-fat variety can be more satisfying,” she adds.“Eating well is about enjoying more fresh and home-cooked wholefoods, including plenty of vegetables and using dressings made from extra-virgin olive oil.”
Sugar plus fat and refined carbohydrates equals unhealthy food.
When we weigh up all the evidence we currently have, it becomes clear that the real diet demon is neither fat nor sugar, but the company they keep. In other words, it’s processed foods’ rich cocktail of fats, sugar and refined carbohydrates. If we can start trimming these foods from our diet, we’ll be well on the way to good health.
A rich, bittersweet history
510 BCThe Persians stumble upon sugar cane when they conquer India. From there, sugar’s sweetness spreads through Africa and as far as Europe.
14th centuryA kilo of sugar sells in Britain for today’s equivalent of $130.
17th centuryThe slave trade in the New World (later the US) grows to meet the booming global sugar demand.
1869A French chemist develops margarine in response to a request from Napoleon III for a cheap butter substitute.
1936Aussies eat about 260g of butter a week, which is like eating a whole block of butter. (By 2000, this figure has dropped to just 55g a week).
1951Australia’s sugar consumption peaks at 57kg per person, per year — more than a kilo a week! (This figure has steadily declined and was 42kg in 2011.)
2011A widely publicised paper by Professor Jennie Brand-Miller points out that despite the substantial decline in sugar consumption, there’s been a steady rise in the obesity rate.
201435 per cent of Australians’ daily kilojoule intake comes from high-fat, high-sugar processed foods that have little to no nutritional value, according to the National Nutrition Survey.