Is swapping high-fat foods with their low-fat alternatives a good way to lose weight?

Written by Nyomi Graef 
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For decades the media and health experts told us to eat low-fat foods to help us lose weight and be healthier. But during this time the rates of overweight and obesity around the world increased. What happened? Had the experts got it wrong? Consultant cardiologist Dr Aseem Malhotra thinks so. He believes that: “Promoting low-fat foods is perhaps the biggest mistake in modern medical history, resulting in devastating consequences for public health.” In fact, Dr Malhotra is just one of many health experts who says that the low-fat era was a disaster.

​There is now a growing trend towards eating less carbohydrates, but eating plenty of healthy fat. And lots of research supports this. Read on to find out more about why replacing all high-fat foods with their low-fat counterparts is unhealthy, and what we can eat instead for better health.
 
What happens when the fat is removed from food? And how can low-fat foods badly affect us?
 
After a lot of fat is removed from a food, the food often doesn’t taste good. To make low-fat food taste okay, food companies often replace the fat with sugar. Sugar is also cheap, and it’s a great preservative, so it cheaply and effectively increases the shelf life of foods. Food companies obviously like this.

Low-fat foods were promoted as better for us/lower in calories than their high-fat counterparts. As a result, many people believed this "expert advice", and believed that they could eat virtually as much of the low-fat foods as they wanted. And they did.

Many low-fat products still contain calories (energy), often about as much as their high-fat counterparts; so portion control is important. The calories are often mostly from sugar and white flour – two common refined carbohydrates (carbs) that are easy to eat in large amounts, so can lead to weight gain. The low-fat versions of foods that contain artificial sweeteners can also cause problems with our health, and can hinder weight loss (a topic for another blog post).
 
It doesn’t help that many low-fat foods are high in added sugar/white flour, low in fibre and low in protein. Why? Fibre and protein both help us feel fuller for longer. Added sugar and white flour, however, do little to make us feel full. So many people find it easy to eat lots of low-fat biscuits, crackers and other desserts/treats, for instance, in one sitting. The result: weight gain and declining health, and an increase in sales and profits for food companies selling low-fat products.
 
Why else are high amounts of refined carbs bad for our health and our waistlines? When we eat carbs, our bodies make the hormone insulin. Insulin is often called the fat storage hormone. This is because it encourages our bodies to store fat rather than burn it for energy. High amounts of refined carbs, especially, leads to high levels of insulin, which encourages weight gain and increases our risk of type 2 diabetes, inflammation and many other health problems.

​"Everything you eat is either a carbohydrate, protein or fat. They all affect glucose, and therefore insulin levels differently. Fat does not cause a glucose or insulin response, and that winds up being pretty important."
​​- Dr Sarah Hallberg, US diabetes and weight loss expert

What are the recommendations for sugar intake?
 
The World Health Organization (WHO) recommends that:
 
“... adults and children reduce their daily intake of free sugars to less than 10% of their total energy intake. A further reduction to below 5% or roughly 25 grams (6 teaspoons) per day would provide additional health benefits.”
 
Want more information about free sugars? Visit the WHO’s website at https://www.who.int/mediacentre/news/releases/2015/sugar-guideline/en/.
 
How much added sugar do Australians consume?
 
On average, Australians consume more added sugar than the WHO recommends for good health. The Australian Bureau of Statistics (ABS) said that:
 
“In 2011-12, Australians consumed an average of 60 grams of free sugars per day (equivalent to 14 teaspoons of white sugar). The majority of free sugar intakes comes from added sugars with an average 52 grams (or 12 teaspoons)...
 
Intakes of free sugars were highest among teenage males (aged 14-18 years), who consumed an average 92 grams per day. The top 10% of the 14-18 year old males were estimated to usually consume at least 160 grams (or 38 teaspoons) of free sugars per day.”
 
How healthy are high-carb low-fat foods and diets?
 
Professor David Haslam, National Obesity Forum (NOF) chairman, said:

"As a clinician treating patients all day every day, I quickly realised that guidelines from on high suggesting high carbohydrate, low-fat diets were the universal panacea, where deeply flawed.
 
Current efforts have failed, the proof being that obesity levels are higher than they have ever been, and show no chance of reducing despite the best efforts of government and scientists."
 
Professor Iain Broom, from Robert Gordon University, said:

“The continuation of a food policy recommending high carbohydrate, low fat, low calorie intakes as healthy eating is fatally flawed.

​Our populations for almost 40 years have been subjected to an uncontrolled global experiment that has gone drastically wrong.”

Dr Joanna McMillan, one of Australia’s leading dietitians, said in a TEDx talk that:
 
"The research actually showed that ... if we replace saturated fat with a whole bunch of refined carbohydrates, we’re in just a bad a state [of health], possibly even worse."
 
Dr David Ludwig, a professor in the Department of Nutrition at the Harvard T.H. Chan School of Public Health, has a similar point of view to Dr McMillan's. According to Dr Ludwig:
 
"Overall, these processed carbohydrates are worse than the fats they replaced."
 
What are healthier food choices?
 
The tide is turning away from low fat, and towards eating patterns with plenty of healthy fats, and less carbs.

Dr Barbra Allen Bradshaw, Dr Carol Loffelmann and Dr Andrew Samis report that multiple high-level scientific studies show that low carbohydrate and ketogenic diets show improvements in diabetes control and equal or better weight loss when compared to low-fat diets.

Leading weight loss and diabetes expert Dr Sarah Hallberg said:

"So, what about the research on this [low-carb diets]? Is this just anecdotal evidence from our clinic? No, there are literally dozens of randomised controlled trials on low carb looking at cardiovascular risk factors, diabetes and weight loss, and they are consistent. It works. There is even a study from The New England Journal of Medicine comparing it with the Mediterranean diet, and it was better there as well. There are also multiple studies that show that low carb decreases markers of inflammation, which is part of the reason it is being looked at for cancer."
 
Celia Smoak Spell, Assistant Editor at Harvard Health Publishing, said:
 
“... Don’t be afraid to go back to fat. Just make sure it’s the healthy fats like avocado, olive oil, and nuts. Don’t cut out the fat, and don’t make a habit of eating products labelled “fat free.””
 
Great advice. The type of fat we eat is very important for our health. Choose fats that promote good health.
 
Trans fat is bad for our health and our hearts. It’s in hydrogenated oils, and many shop-bought cakes, doughnuts, biscuits and more. Check food labels to see if the food contains hydrogenated fat, including partially hydrogenated fat. Avoid foods with trans fats.
 
The fat in many cheap vegetable oils, and fat that has been re-heated often and/or raised to very high temperatures, is also bad for us. Any goodness that the fat might have is destroyed by excessive heat, and re-heating the oil over and over again.

Dr Sarah Hallberg and Dr McMillan are among many nutrition experts who also recommend (among other recommendations) that we eat "real food" (not highly processed/junk foods), especially vegetables. 
 
Generally, the more processed a food is, the more essential vitamins, minerals, fibre and other nutrients are destroyed/lost. Fibre makes us feel fuller for longer, so we are less likely to overeat on whole grains than refined grains. So choose brown rice and wild rice instead of white rice, and whole wheat flour instead of white flour, for example. Also, if you eat bread, buy genuine wholemeal bread, not bread with only 40 per cent wholemeal flour, for instance.
 
Eat mostly foods with low or no added sugar. A low-fat biscuit/other treat/dessert packed with added sugar/white flour is not good for our health nor our heart. Just because the food is low in fat – and might have some healthy-looking symbol(s) on the packet – does not mean that a sugary junk food is healthy! Marketing nonsense! So eat low amounts of high-sugar/high-white flour muffins, cakes, biscuits, pastries and so on. Sugar is also hidden in many foods including many sauces, salad dressings, spreads, and soups. Limit these foods.
 
Summary
 
The low-fat versions of many foods can be unhealthy and can cause weight gain. For better health, and easier weight loss, eat mainly healthy wholefoods, with plenty of fresh fruit and veggies. Eat low amounts of food and drinks with lots of added sugar/other refined carbs. Avoid trans fats, and fats and oils that have been heated often/heated to very high temperatures. Choose foods high in good fat, such as olives, extra virgin olive oil, avocados, nuts and seeds.
 
References
 
Allen Bradshaw, B, Loffelmann, C and Samis, A, 2019, Opinion: Is Canada’s new food guide a pathway to health for most Canadians?, Vancouver Sun, https://vancouversun.com/opinion/op-ed/opinion-is-canadas-new-food-guide-a-pathway-to-health-for-most-canadians
 
Bodkin, H, 2016, 'Eat fat to get thin': Official diet advice is 'disastrous' for obesity fight, new report warns, The Telegraph, https://www.telegraph.co.uk/news/2016/05/22/eat-fat-to-get-thin-30-years-of-flawed-dietary-advice-is-disastr/

Cutting carbs, not calories, may be key to long-term weight loss, 2019, Harvard T.H. Chan School of Public Health, https://www.hsph.harvard.edu/news/hsph-in-the-news/carbs-calories-weight-loss/
 
Fact check: Is sugar consumption down while obesity rates have risen?, 2018, ABC News,  https://www.abc.net.au/news/2018-08-03/fact-check-sugar-consumption-and-obesity/9999182

Hallberg, S, Reversing Type 2 diabetes starts with ignoring the guidelines, 2015, TEDxPurdueU Talk, YouTube, https://www.youtube.com/watch?v=da1vvigy5tQ

McMillan, J, 2014, Eat for real change, TEDx Talk Macquarie University, YouTube, https://www.youtube.com/watch?v=fbeFn1Xcqo4
 
Smoak Spell, C, 2016, There’s no sugar-coating it: All calories are not created equal, Harvard Health Publishing, https://www.health.harvard.edu/blog/theres-no-sugar-coating-it-all-calories-are-not-created-equal-2016110410602
 
WHO calls on countries to reduce sugars intake among adults and children, 2015, World Health Organization, https://www.who.int/mediacentre/news/releases/2015/sugar-guideline/en/
 
4364.0.55.011 - Australian Health Survey: Consumption of added sugars, 2011-12, 2016, Australian Bureau of Statistics, https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4364.0.55.011main+features12011-12