In this post from The Sydney Morning Herald, Sarah Berry clears the air on some long-held diet myths that have been debunked by the ever-evolving field of nutritional science.
“Dietary advice does not merely need a review; it should not have been introduced.”
This is the arresting conclusion made in a new review published in BMJ’s Open Heart journal.
In this instance, the researchers are referring specifically to the fat recommendations in national dietary guidelines.
Nutritional science is a dynamic field and knowledge is growing quickly, debunking long-held beliefs. Beliefs like margarine is better than butter or that fat makes you fat.
Here are 10 common nutritional beliefs that have been debunked by science.
1. Saturated fat is bad
This myth started in the 1970s with the flawed Seven Countries study, which looked at the correlation between saturated fat intake and heart disease among 12,763 men from seven different countries.
The study failed to consider whether the men smoked, did exercise or consumed sugar, among other factors.
Saturated fat, as the new BMJ study has found, is not bad for weight or heart health.
In fact, it can even be good for us – if it’s coming from healthy sources like organic eggs, coconut oil, butter and range-raised, grass-fed meat instead of salami and fast food.
“The truth is, saturated fats from animal and vegetable sources provide the building blocks for cell membranes and a variety of hormones and hormone-like substances, without which your body cannot function optimally,” says Dr Joseph Mercola.
“Any dietitian working with clients for weight loss or to improve blood lipids knows it is the fat balance in the diet that is crucial, not just the saturated fat intake,” adds dietitian Susie Burrell. “Anything is bad if we have too much of it, but 15-20g saturated fat each day via dairy or meat and a balanced diet is no issue.”
Bottom line: As part of a balanced diet, saturated fat is not bad. In fact, when it comes from the right sources and is eaten in moderation, it can be beneficial to our health. “Dietitians are now recommending that people focus on whole foods as opposed to purely on nutrients,” says accredited practising dietitian from Nutrition Plus Melanie McGrice.
2. A low-fat diet is better for health
This comes from the same school of thought that labelled fat bad. It has, thankfully been debunked on multiple levels.
“Low-fat processed foods tend to contain refined carbohydrates and added sugars – in general processed foods are not a good choice,” Burrell says.
Bottom line: It’s still a matter of moderation, but this myth needs skimming. The Dietitians Association of Australia suggests about 70 grams of fat per adult per day. To put it in perspective, an avocado has about 15 grams of fat. “In recent years we have learnt how important a small amount of fat is for part of a healthy diet – even for those who want to lose body fat,” McGrice says.
3. Salt is the devil
A new study, conducted over 10 years, found that sodium intake was not associated with higher death rates, cardiovascular disease or heart failure.
“There is a need for stronger evidence, preferably from rigorous controlled trials testing additional thresholds for sodium intake, before applying a policy of further sodium restriction to older adults beyond the current recommendation for the general adult population (2300 mg/dl),” the authors said.
In fact a separate study of more than 100,000 found that a diet too low in salt can have negative health implications.
“Research in nutragenetics is now showing us that some people are more sensitive to salt than others, so salt’s impact on your health may be affected by your DNA,” note McGrice.
Bottom line: For healthy individuals, without blood pressure or heart issues, a moderate amount of salt isn’t bad. Instead of slavishly counting milligrams, one idea is to eat real (not processed salt-packed foods), add salt where necessary for flavour and leave it at that. “There are worse things going on with Australian’s diet than salt – if you cut back on fast and processed foods, you will automatically cut back on salt,” Burrell points out.
4. Sugar is the dietary devil with its empty kilojoules
OK, sugar sure looks and tastes a treat. But, it can be very badly behaved. If we eat too much of it, that is.
It is not just the way it delivers empty calories, completely devoid of nutrition. It is the way it messes with your insulin, making you want to go back for more. And more.
It’s the way it can cause metabolic problems, diabetes and even cardiovascular disease.
We currently consume too much sugar and there is no doubt we need to dabble less in the sugar dance.
It’s also more than just empty kilojoules
BUT, a little sugar is not the dietary devil, as some food activists say.
“Added sugars via soft drink, lollies, snack foods offer little nutritionally and should be kept to a minimum in the diet,” Burrell advises. “A small amount of natural sugars in fruit and dairy is no cause for concern.”
Bottom line: For healthy, active people who eat a well-balanced diet, a small amount of sugar is sweet. “If you’re undertaking plenty of physical activity, and brushing your teeth regularly, there’s no harm in having some jam on your toast or a little chocolate syrup in a glass of milk to add flavour and variety to your diet,” McGrice says.
5. Eggs are evil
“Eggs are one of the most nutrient dense natural foods available,” says Burrell.
Recent research has debunked the idea that eggs are bad for heart health and cholesterol in healthy individuals. In fact, eggs are rich in iodine, for making thyroid hormones, and phosphorus, which is essential for healthy bones and teeth. They are also packed with vitamins A, B, E and D.
As well as this, eggs activate serotonin, the happy hormone.
“Eggs have been recommended as a great source of nutrition by the Australian Dietary Guidelines for over a decade now,” McGrice points out.
Bottom line: Eggs are good for body and mind, so get cracking, preferably with free-range or organic eggs, which studies have shown to be more nutritious.
6. Multiple small meals beats three square meals
Despite a recent trend towards small meals spread evenly throughout the day to fuel the metabolism, there is no solid evidence that this happens.
Rather, research has revealed that it is the total amount of food eaten in a day that makes the difference to appetite, fat loss and metabolism. This is regardless of whether you’re consuming three square meals or six small ones.
“Whether you should eat three meals or include snacks in between largely depends upon your routine and lifestyle,” McGrice says.
“Many Aussies snack too much with 6-8 eating occasions a day,” adds Burrell. “Three to four suit most people – breakfast, lunch, mid afternoon and dinner.”
Bottom line: Watch your quantities however you consume them and stick with what works for you, but it is not true that eating more frequently will burn more kilojoules over the course of the day.
7. Low fat dairy is better for health and weight loss
Many health guidelines recommend low fat dairy to minimise kilojoule intake. Additionally, full fat dairy has been slandered by the saturated fat equates to a greater risk of heart disease and obesity.
Interestingly, studies have shown an inverse association with full fat dairy and obesity risk.
As well as this, overall intake of dairy products was not associated with early death. The conclusion of one long-term study: “A possible beneficial association between intake of full-fat dairy and cardiovascular mortality needs further assessment and confirmation.”
Adds McGrice: “The difference in fat between full cream milk versus low fat milk is only 2% so doesn’t amount to a very big difference in kilojoules anyway unless you’re drinking litres of milk every day, the key message is to ensure that you’re including three serves of dairy or dairy alternatives in your diet each day.”
Bottom line: Full fat dairy has been linked with a reduced risk of obesity and possibly even heart disease. As with anything the key is easy does it. “If the rest of the diet is low in processed and fast foods, a small amount of full cream dairy can be a part of a balanced diet,” Burrell says.
8. Cooking with olive oil is bad
This rumour has been doing the mainstream rounds in recent years. Olive oil has been called the healthiest fat on the planet. It runs its liquid gold goodness right through the Mediterranean diet, is abundant in antioxidants and improves risk factors related to heart disease, cholesterol and diabetes.
But, some researchers have said that olive oil burns at low temperatures compared to other types (like coconut oil), and when oil is overheated, it produces toxic chemicals called lipid peroxides.
Various other studies however have found this to be untrue and found heated olive oil to be more stable than oils like sunflower or canola.
“Deep frying in olive oil will destroy the oil but olive oil still offers the health benefit of acting as a rich source of antioxidants when used in cooking at medium temperatures,” Burrell explains.
“Variety is the spice of life and I think that it’s a great idea to vary the types of oils that you use to create different flavours in your meals,” McGrice suggests.
Bottom line: Olive oil can tolerate heat and is OK to cook with as well as being wonderful in salads… and pretty much everything else.
9. Skipping breakfast is a terrible idea
One study found that while eating breakfast resulted in greater initial weight loss among participants, those who tended towards eating later instead were better at maintaining fat-free mass, which impacts metabolism.
“What time you have your first meal of the day really should come down to your lifestyle and what you eat for your first meal,” McGrice advises. “If your first meal is a doughnut at 11am, then maybe you should be considering eating breakfast.”
Adds Burrell: “Eating the first meal of the day as early as possible helps to boost metabolic rate.”
Bottom line: Breakfast is known to have a positive impact on cognition, but skipping it won’t necessarily slow your metabolism. Start the day how it feels natural for you and eat when you’re hungry.
10. Fasting slows your metabolism and increases cortisol
Dr Michael Mosley popularised the idea of intermittent fasting. But, rumours persist that going without food will slow your metabolism.
This is not true, so long as the fasts are for short periods, research has revealed.
“New research suggests that occasional fasting may even boost metabolism, if done in the right way,” says Burrell.
One recent study found beneficial effects of intermittent fasting on glucose regulation and cardiovascular function. Other studies have found that overnight fasting (after dinner waiting 12 hours to eat breakfast) can improve blood sugar and metabolism levels, help fight high cholesterol, diabetes and obesity.
“Your metabolism slows when your body runs out of fuel and has to start breaking down muscle mass, but your body should have enough glycogen stores to last a few days before this occurs,” McGrice says.
Bottom line: Prolonged fasting and severe calorie restriction disturb the endocrine system, but intermittent fasting can have positive effects on our health and waistlines.