Spinach makes us strong and eating fish makes us smart. Saturated fat is bad, we should never snack before bedtime. Breakfast, meanwhile, is essential every single day. These are absolute truths that should never be questioned, right?
Wrong. They should be seriously questioned, according to Tim Spector, author of The Diet Myth and Spoon-Fed: Why Almost Everything We've Been Told About Food is Wrong. Spector is professor of genetic epidemiology at Kings College, London, and he wants to start a revolution on how we think about food.
"The purpose of The Diet Myth was to explain how gut microbes interact with food, but after its publication six years ago, I really started to notice how bad eating habits had become in Australia, England and the US," he says.
"People's diets have been manipulated by a series of factors. Many of these are the fault of the food industry, but also the very poor state of nutrition research and lack of funding. I set out to write Spoon-Fed to point out what bad shape we're in."
Published by Penguin, Spoon-Fed is "illuminating" and "incredibly timely", according to English-Israeli chef Yotam Ottolenghi.
Spector debunks beliefs such as sugar-free drinks are a safe way to lose weight, fish is the healthy option and exercise will make you thin (more on those later).
When Spector was researching Spoon-Fed, Clare Collins, laureate professor in nutrition and dietetics at the University of Newcastle, was creating an online course to help Australians make their own healthy eating decisions.
Collins' free six-week course, The Science of Weight Loss: Dispelling Diet Myths, is now open for enrolment through online learning provider EdX until March 10.
"More than 70 per cent of Australian men and 50 per cent of women are living with excess weight, which means weight loss is often on a lot of people's minds," she says. "The course is designed to address the same questions."
Topics include metabolic rate, how to identify fad diets, and how to maintain weight loss. The course aims to change conversations around food, a topic Spector believes is too often overlooked by educators.
"I want people to be interested in food, but rather than oversimplifying it, we need to acknowledge that food is complex and deserves full scientific attention," he says.
"It's a topic that needs to be taught to children. It's as important as reading and writing."
To cut through some of the complexity and ever-evolving research around weight loss, Good Food asked the experts to highlight seven myths that need busting for healthier eating, whether you want to lose weight or not.
1. Breakfast is the most important meal of the day
"Aussie kids are Weet-Bix kids!" We're also a nation of happy little Vegemites, avocado toast fetishists, and all-day-long egg lovers. But is breakfast as vital as dietary guidelines, food companies and grandparents would have us believe? Spector says no.
"We have been led to believe breakfast is the right thing to do through a series of bad research and breakfast cereal marketing. We've been told that skipping breakfast is very bad and could lead to diabetes, weight gain and kids going crazy in school.
"However, there's no evidence for any harm at all, and some evidence points to occasionally skipping breakfast as a useful strategy for reducing weight."
Research conducted though ZOE, a nutritional science company co-founded by Spector, found that as people get older, they tend to metabolise things better in the evening than before lunch.
"And yet we're told that everybody should have their calories in the morning because of studies originally done on 20-year-old students," says the professor.
Evidence is also growing that increasing fasting intervals to about 14 hours can reduce insulin levels and promote weight loss. Further, Spector says fasting may help create a healthier gut microbiome – the community of 100 trillion microbes living mainly in our small intestine.
The microbiome helps regulate our health and metabolism. Emerging data suggests short periods of fasting may lead to certain microbe species replicating and tidying up the gut to make it healthier and more efficient.
"I think everybody should skip breakfast once a week," says Spector, adding that anyone omitting the meal should track how it affects their energy and mood through the day, plus any long-term weight loss or gain.
"There are some people that do benefit from eating their kilojoules earlier in the day, and others in the evening. It's probably very personal. The message here is don't believe something just because your mother told you it's true. Do your own experiments."
The high-fat, low-carbohydrate keto diet is hard to sustain. Photo: iStock
2. Carbohydrates will make you fat
You can't talk about weight-loss fads in 2021 without talking about the ketogenic diet, more commonly known as keto. The high-fat, low-carbohydrate diet is designed to put the body into a metabolic state (ketosis) that makes it super-effective at burning stored fat.
"Fad diets often fade away and come back under a different name, and keto is just an extreme version of the Atkins diet," says Dr Jessica Danaher, a lecturer in nutrition at RMIT University, Melbourne.
"A lot of the time people can lose weight on a restrictive diet such as keto, but that's probably not the way you want to eat the rest of your life. The best diet is one that's sustainable."
Carbohydrates shouldn't be seen as the bad guys either. "People often get confused about the quality of carbohydrates in different foods," says Collins.
"Absolutely you should reduce your junk food carbs, but you shouldn't reduce carbohydrates found in whole grains, which are a good source of fibre. Plus, there's lots of research suggesting whole grains are particularly useful in lowering the risk of cardiovascular disease."
A 2018 clinical trial in California also found an equal number of adults lost weight on a high-fat and low-carb diet as on a high-carb, low-fat eating plan. Again, it's personal.
3. Exercise will make you skinny
Clocking up multiple kilometres each day on a fitness app? Fantastic stuff, keep it up. However, while receiving that 10,000 steps alert is "a nice placebo", Spector says all that walking won't lead to weight loss.
"There is this idea that if you exercise enough you don't have to worry about what you're eating, but unless you're an Olympic swimmer, that's not quite true. This isn't something people in the gym and fitness business like to hear."
It's not something sugary beverage companies such as Coca-Cola like to hear either, which is why they spend millions funding research to shift obesity blame away from diet and towards inadequate physical activity.
Virtually all non-biased research shows that exercise in normal amounts won't lead to weight loss, Spector writes in Spoon-Fed.
About 80 per cent of our energy expenditure is due to cells burning fuel just to keep us alive and digesting food. Another 10 per cent of expenditure is used on small movements such as standing and sitting, which, for most people, leaves only the remaining 10 per cent to be manipulated.
Further, exercise stimulates appetite and can lead to overeating. Kilojoules burned during a high-intensity workout are easily replaced with a protein shake and an extra slice of pizza.
But – and this is a big "but" – Spector also says exercise should arguably be our "number-one prescribed drug". It reduces the risk of diabetes and may well reduce heart disease and high blood pressure, too. Other studies have shown it can help depression and the severity of dementia symptoms. In other words, don't stop moving.
The number of fries varies between each individual serving. Photo: iStock
4. Kilojoule counting is reliable and easy
Speaking of kilojoules, at the core of every weight-loss diet is the rubric that burning more energy than you consume leads to success. Simple in theory if you assume all kilojoules are created equal and are easy to count. According to Spector, however, this is far from the truth.
"It's impossible to count kilojoules accurately," he says. "For one, the energy labels on food products and menus are almost always incorrect."
Consider the variables in a McDonald's value meal for example, from the number of individual fries in each serving, to a soft drink's shifting percentages of post-mix syrup, fizzy water and ice.
Additionally, says Spector, some people will react differently to a kilojoule depending on whether they consume it as a fat or carbohydrate.
Participants in the PREDICT (Personalised Responses to Dietary Composition Trial) study started by Spector in 2019 were fed special muffins while being monitored for sugar peaks and one in four people experienced a peak and subsequent dip after eating the baked item. They also reported increased hunger and consumed 10 per cent more kilojoules over the next 24 hours than participants who didn't have the dip.
"That was really interesting because it means the way your body responds to kilojoules from different sources will determine how much food you eat," he says.
"We now know from other experiments that if you give people junk foods and whole foods in identical kilojoule amounts, the junk food will always generate more hunger later. The kilojoule is camouflaging lack of quality."
When you also consider everyone burns fuel in different ways at varying levels of efficiency – dependent on factors including age, genetics, and the unique gut microbiome – any attempt to accurately count kilojoules consumed and burned is more or less a fool's errand. Dang.
5. Detoxing improves health and wellbeing
The concept of detoxing was thoroughly debunked by health professionals long before Gwyneth Paltrow was hawking cleansing "superpowders". Nevertheless, the global detox product market is expected to reach $US70 billion ($90 billion) by 2025, so someone's buying all those yerba teas and thistle pills.
Detox-spruiking products are largely snake oil, as our bodies already have detoxification well under control, says Collins.
"The liver is your major detoxification organ – the demolition yard to break down unwanted chemicals. And your kidneys are the body's filter, like the boom gates you see in waterways."
Any "cleansing" or detox diet that involves restricting food should not be attempted without consulting an accredited practising dietitian, who will most likely tell you it's bunkum and to eat more vegetables instead.
6. The healthiest diet is plant-based
With junk food companies well on board the plant-based train, marketing teams are trying their hardest to convince consumers that vegan eating is the healthiest thing since MeadowLea on multigrain.
"Veganism can be healthy, provided you're getting the majority of your nutrition from vegetables, fruits, wholegrains and healthy meat alternatives," says Danaher. "You don't want to rely on junk food that's vegan, or ultra-processed plant-based snacks. A vegan burger is still a burger.
"Anyone looking to exclude certain food groups from their diet should also consult an accredited practising dietician and make sure they're not setting themselves up for a nutrient deficiency."
Purple and red coloured fruits and vegetables are high in polyphenol. Photo: iStock
7. What's good for me is good for you
By now, it should be clear there is no one-size-fits-all diet. The "average person" is rare.
"There are loads of different ways to lose weight, it's keeping the kilograms off that's the hard part," says Danaher. "I wouldn't get caught up with someone screaming from the rooftops about keto, for example, just because it worked for them. There's every chance it won't work for the next person."
For anyone who has tried every diet in the playbook with limited results, Danaher recommends creating an individualised nutrition plan in consultation with a dietitian. Spector, meanwhile, suggests eating food to cultivate a "garden in your gut".
"Instead of worrying about kilojoules, focus on improving your gut microbes to help metabolism and get your weight under control. It's a really different mindset to saying, 'I have to lose 10 kilos in six weeks'. Every time you put something in your mouth, think about whether it's good or bad for your microbiome."
Spector's rules for healthy eating are as follows: avoid highly or ultra-processed foods, which are often manipulated by the manufacturer to make us eat more than we need to. Also experiment with meal skipping, which is increasingly recognised as having health benefits.
Try to eat between 20 and 30 plant species a week to create healthier and more diverse gut microbes. Polyphenol-rich plants are great to include in the mix, as evidence suggests they can help metabolism and weight loss, too. Bright or dark colours often indicate high levels of polyphenols in a food, so consider eating more berries, red grapes, beans, red cabbage and chillies.
Finally, a growing body of research indicates the gut loves to be nourished once a day by a fermented food such as kefir, kombucha, kimchi or 'kraut.
"Those rules aren't very hard to follow and can be adapted to suit your own tastes and circumstances," says Spector. "You're not going to lose weight suddenly, but you will notice a difference. And over the course of a year, you'll feel a whole lot better."
Kombucha is better for your microbiome than a Diet Coke. Photo: Jonathan Carroll
*A note on sugar
Advice around sugar is much the same as it always has been (limit intake, go for natural sources), but a recent systemic review found sugar-free soft drinks show no clear benefit for weight loss compared to regular soft drinks. Possibly because artificial sweeteners can hide nasty chemicals, and we're only feeding our long-term sugar addiction. The brain may also feel conned into thinking it was receiving real sugar and when it doesn't arrive will tell the body to regain this energy by storing fat. Your dentist will thank you for drinking less Diet Coke, too.