• Diet soft drinks: the better of two evils? (AP Photo/Jeff Chiu)Source: AP Photo/Jeff Chiu
We tackle the big question about your take-away request: if you order a diet soft drink with a burger and fries, will it really help you to lose weight?
By
Yasmin Noone

8 May 2018 - 2:33 PM  UPDATED 8 May 2018 - 3:03 PM

We all know that sugar-fuelled soft drinks are bad for us and regular consumption can cause us to put on weight.

But what about diet soft drinks: are they really a better alternative for weight loss?

Accredited Practising Dietitian, Dr Alan Barclay, says people who regularly consume a diet high in sugar, filled with soft drinks, can lose weight by switching to diet soft drinks.

"In humans, there’s some strong evidence saying that consuming intense sweeteners will not make you put on weight,” says Dr Barclay. “In fact, if you replace the sugar [in your diet] with an intense sweetener, you will lose weight."

Diet soft drinks, beverages sweetened with non-nutritive sweeteners (or intense sweeteners) like Sucralose or Stevia, do not contain carbohydrates and have very few calories.

“In fact, if you replace the sugar [in your diet] with an intense sweetener, you will lose weight."

“So if you do consume a lot of free or added sugars then you can safely switch to an alternative sweetener or a diet soft drink, and that will help you to cut down on calories and carbohydrates from your diet."

However, he explains, if you don't drink soft drinks at all, you will not lose weight by introducing diet soft drinks into your routine. "You won’t gain weight either by drinking diet soft drinks. It is likely to produce no difference [on your weight] whatsoever. 

“But if you go and order a burger, fries and a diet beverage, the diet drink is not going to make you lose weight as the overall meal is unhealthy." 

A study, published in the Journal of Nutrition earlier this year, looked at the impact of low-calorie sweeteners on glycemia and weight in lean adults. It found that when the artificial sweetener tested, aspartame, was ingested regularly over a three-month period, it had no effect on glycemia, appetite, or body weight. 

Another study from 2016 involved a systematic review of evidence from human and animal studies on low-energy sweeteners and energy intake and weight. It concluded that "overall, the balance of evidence indicates that use of low-energy sweetener in place of sugar, in children and adults, leads to reduced energy intake and body weight, and possibly also when compared with water".

Dr Barclay explains that, contrary to popular belief, the consumption of intense sweeteners does not lead to an increased desire for sweet and sugary foods.

“This is not the way the human body works," he says. "Evidence from randomised controlled trials in humans indicates that intense sweeteners can satisfy an individual’s desire for sweetness if consumed before a meal.”

“But if you go and order a burger, fries and a diet beverage, the diet drink is not going to make you lose weight as the overall meal is unhealthy." 

However, Dr Barclay adds that neither product – sugar nor an intense sweetener – are essential food products. They offer no nutritional value and both can be cut from your diet as needed.

Diabetes Australia maintains the position that people should not rely on artificial sweeteners or products, like soft drinks, as a health or weight loss strategy.

The body says online that claims about sugar substitutes having a lower GI than sugar are untrue.

“Many of these claims are actually irrelevant,” the body says online. “For example, the GI of sugar substitutes becomes irrelevant when they are only used in small amounts. A teaspoon of any sweetener is going to have a similar impact on blood glucose levels, it doesn’t matter if it is high GI or low GI.”

The advocacy body recommends that sugar substitutes be used in small amounts to reduce the impact on blood glucose levels and weight.

Diet soft drinks, dementia and metabolic health

Research from Boston University USA, released last year, shows that drinking a diet soft drink every day could significantly increase a person's risk of suffering a stroke or developing dementia. The participants involved in the research who drank at least one artificially-sweetened beverage a day were three times as likely to develop a ischemic stroke and 2.9 times as likely to develop Alzheimer's disease dementia.

Meanwhile, a University of Sydney study, released this week, examined how diet beverages impact the metabolic health of rats compared to sugar sweetened drinks. 

The study, published in Physiology and Behaviour, included two experiments designed to assess the effect on female rats of switching to either water or an artificially sweetened saccharin-based solution following unrestricted access to a sucrose-based sugar solution. Both the groups that switched to water or artificial sweetener recovered the abilities they had lost as a result of excessive sugar consumption.

“Given the controversy over diet drinks, it’s notable that switching from sugar to a solution containing an artificial sweetener like saccharin produced the same improvement as switching from sugar to water."

Senior author Emeritus Professor Bob Boakes says it’s generally accepted that high consumption of sugar-sweetened beverages is a risk factor for weight gain and associated metabolic diseases. However, he said there is ongoing debate about whether this risk is reduced by switching to artificially sweetened beverages.

“Given the controversy over diet drinks, it’s notable that switching from sugar to a solution containing an artificial sweetener like saccharin produced the same improvement as switching from sugar to water,” says Professor Boakes.

“So while it is important to reduce sugar consumption to improve health, the benefits are likely to be greater if we can get children and young adults to quit before some irreparable damage is caused.”

Co-author Dr Kieron Rooney notes that the capacity to recover may be dependent on the amount of time spent consuming sugar before quitting.

“Our data suggests that the capacity to recover from the damage caused by excess sugar consumption is influenced by the amount of damage or length of exposure,” says Dr Rooney. “So while it is important to reduce sugar consumption to improve health, the benefits are likely to be greater if we can get children and young adults to quit before some irreparable damage is caused.”

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