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Artificial Sweeteners: The Good, The Bad and The Ugly

Never has there been a bigger divide in the nutrition world than between the clean eating folk versus the flexible dieting folk. Ok maybe the vegans versus the meat eaters. Or even the low carbies versus the high carbies. Regardless, artificial sweetened products have caused a lot of controversy in their relatively short life-span since their inception almost three decades ago.

The world is in an obesity epidemic and giant food corporations have invented ingenious ways to target the dieter. With sugar being supposedly ‘bad for us’ the public need an alternative to it. So diet drinks and low calorie snacks have hit the aisles in a mission to counteract this alleged sugar problem.

But if we are getting fatter and sicker; how come these diet products have not stopped the obesity epidemic?

Today we play devil’s advocate and look at the big picture. The Good, The Bad and The Ugly side of artificial sweeteners. Do they work? Are they safe to consume? Are we even correct in calling diet drinks… diet drinks?

Just an FYI - the studies referenced below interchange between aspartame, saccharin and sucralose because we want to keep it as easy for you as we can. However there chemical differences between them and slight differences in sweetness. But not in the grand scheme of a diet. So they get discussed as one group.

So let’s start with…

The Good

Artificial sweeteners can be a good strategy for keeping you on track on a diet as they replace food and drinks that are calorie dense, non-nutritious, and non-filling.

Artificial sweeteners have next to no calories and if we have an individual that guzzles down Coke and Pepsi for fun but wants to shed some pounds then a simple switch to a diet option will remove empty calories. Yes ideally everyone should choose water for the health reasons alone but this easy switch is great for someone just starting out on diet because it helps keep someone on track as we tactically add something sweet to avoid any sugar cravings. Happy days.

We know that the long game is probably one of the most important factors to long term sustainability on a diet, even when you make it to your desired weight. After all keeping it off is just as tricky as losing it.

Let’s look at the science. One study shows us when aspartame was substituted for sugar in a metabolic ward; there was a 25% reduction in overall calorie intake (although calories were removed to accommodate the inclusion of artificial sweeteners but it’s still a positive result.)[1]

If you struggle with your calorie intake and want a quick fix than a can of Diet Coke at almost 0 kcal is a great option when you have a can of Coke that has up to 140 kcal. The effect is even greater if you drink soda from the big litre bottles with calories reaching very high levels.

"But hold on" you ask. "Wasn't there a study done on rats where they all got cancer because they drank diet drinks?"

Let's debunk this once-and-for-all. Back in the 70’s a study was carried out on rats who were given saccharin (an form of artificial sweetener) and subsequently developed bladder cancer. [2] This study was criticized and subsequently detracted because the rats were not given a normal dose that an every day person would expect to consume. You are looking at the equivalent of about 50 cans per day. The rats were basically drowning in the stuff!

But it's not all good news however...

The Bad

Long term artificial sweetener intake may actually cause weight gain.

Why? Because artificial sweeteners could be affecting your brains power to count calories and therefore track energy intake.

To give you context one study compared the follow-up results of artificial sweetened beverages to sugary beverage drinkers. They found that after a 7-8 year follow up the BMI of the sugary beverage drinkers were in fact lower and 47% higher in the diet drinkers. [3]

Too add fuel to the fire, in the same study from the good section above participants who knew they had been switched over to aspartame actually overcompensated with an overall increase in calories and the rest of their diet went to pot.

We could have a problem here.

It may be that people on a diet are actually still on a weight gain trajectory and are none-the-wiser, even if they switch to diet sodas.

When we consume energy in the form of food and drink in our diet they first hit our taste buds. Think of your taste buds as the front desk when it comes to energy going in. They can register and inform the brain how many calories you have consumed. So once you have a sweet substance entering the body at zero calories the brain now thinks that sweetness equals zero calories.

If your taste buds continue to underestimate the calorie count of actual calorie dense sweet foods, like a biscuit for example, because they register sweetness as equal to zero calories it means you could be overeating. Because your brain now believes that biscuit to be zero calories.

And if you still take in more energy than you burn, even with diet drinks, you still gain weight. So in fact just because it says diet on the side of the can does not mean you are even on one in the first place!

Finally we have…

The Ugly

Artificial sweeteners may invoke headaches, dizziness, gastrointestinal problems or mood alterations in people that habitually drink them. [4]

Why is it ugly you ask? Because the results aren’t actually clear at this stage. A lot of these symptoms have been self-reported by users which inevitably has its limitations. Variables such as; stress, sleep levels, hydration levels, problematic foods in the diet, could bring on some of if not all of the above symptoms, especially headaches or changes in mood. So it was never actually the artificial sweetener but something completely different.

If you think that some of these symptoms happen to you but you aren’t sure then good old fashioned bio-feedback will be your friend. So consume a potential problem food or drink and see how you feel from the time you consumed it for up to 2-3 hours afterwards. If you drink a can of Diet Coke and feel terrible afterwards you can be quite sure it was the Diet Coke.

Just try not to go ‘looking’ for symptoms that may not even be there in the first place. Like when people think they are gluten intolerant and get bloated when in fact they are not. Be honest with yourself and look for the signs.

It could be that the occasional diet dink is fine. But can-after-can-after-can makes you feel bloated, gassy and drained of energy, In that case just stick to the odd glass here and there.


So there's mixed results on artificial sweeteners and it's really going to be dependent on the individual.

Your best bet is to test it out for yourself and see how you respond. Failing that then moderation is always a good method to stick to. Some people avoid it which works well for them. Others opt for a can a day and report being totally fine as well.

There should be nothing wrong with a Diet Coke or Pepsi with a calorie controlled homemade chili con-carne. However a diet coke with a big Mac and fries is not ideal and the diet coke is going to be the least of your concerns!

If you are classified as obese or overweight we feel diet drinks or artificial sweeteners are a great short term fix to your energy imbalance problem. Use them strategically alongside water. But if you consistently reach for the biscuit tin after a can, feel a bit sick or headachy after consuming artificial sweeteners then reconsider your options.

We also mentioned that there are differences between aspartame, saccharin, sucralose and even Stevia which may affect how you feel afterwards. Again experiment with what works for you. You may be fine on aspartame but not on sucralose! Become a guinea pig and go find out. But please, don't drink 50 cans of Diet Coke per day.

For more of the sweet-science head on over to Angel Nutrition on Facebook or Instagram!


  1. https://www.ncbi.nlm.nih.gov/pubmed/910740

  2. https://www.nhs.uk/Livewell/Goodfood/Pages/the-truth-about-saccharin.aspx

  3. https://www.ncbi.nlm.nih.gov/pubmed/18535548

  4. https://www.cdc.gov/mmwr/preview/mmwrhtml/00000426.htm

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