Diet soft drinks – Are they really that bad?

You can call them fizzy drinks, pop, soda or soft drinks – but whatever you call them, we all know that they’re not exactly classed as 'healthy', right? Regular soft drinks have been linked with conditions such as obesity and diabetes to name just a few. (1)(2) The sugar content in a regular soft drink is usually over the recommended added sugar intake for an adult per day, never mind a child. Yet we as a nation continue to consume them on a daily basis.

Then we have diet soft drinks, which I will be talking about now. So, what exactly makes a soft drink ‘diet’ worthy? Well, diet soft drinks are usually sweetened with low- or no-calorie sweeteners in order to make them taste just like their regular soft drink equivalents. Aspartame and sucralose are two popular sweeteners used in diet drinks.

"More and more parents are wising up to the volume of added sugar in processed foods and drinks but many are concerned about the alternatives'.

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Should you limit your child’s intake of colas and squashes altogether or is it safe to let them have the odd diet soda or sugar free cordial?

Unless you are hiding under a rock these days, you more than likely have read about/watched some negativity towards diet drinks stating that they are worse for you than regular soda. You may have heard statements such as ‘diet drinks make you feel hungry, which means you eat more, therefore cause obesity in some people’, ‘diet drinks use aspartame, therefore they give you cancer’, and so on. There have been some very bold statements made about diet drinks that would cause some people to worry, and understandably so. If it's splashed all over social media/the web then surely it must be true? Well, no.

These claims are not backed up with any sound evidence/research. You might read an article on Facebook that says 'according to such and such study, diet soda is worse than regular soda'. Well, it has referenced some research so surely it's not lying? The danger these days is that a lot of people don't know what to look for in research papers, or how to tell if they are actually telling us the truth and if the results are relatable to real life and real people.

In relation to the bold statements made in the media about diet drinks causing cancer, well, in 2005 a lab study found more lymphomas and leukaemias in rats when very high doses of aspartame were used. (3) What is classed as a ‘very high dose’ in the study you ask? Oh, just the equivalent to drinking 8 to 2,083 cans of diet soda DAILY!! This is exactly why we have to be careful of the things we read on social media and what we believe. First of all, the study was on rats, and secondly the dosage is well beyond any normal person’s daily intake of aspartame/diet soft drinks.

Also, with regards to diet drinks (sweetened with aspartame) increasing a person’s appetite - there is no convincing data that exists to show that aspartame positively or negatively affects appetite. (4) However, this is a bit of a grey area and one that seems to have different effects on different people. Some say that a can of diet coke can curb their food cravings, whilst others argue that it does the opposite and makes them feel even hungrier! This is simply another case of 'what works for you'. If you find that diet drinks help curb your cravings, perfect! If not, and you find diet drinks increase your hunger, then maybe you should try to stay away from soft drinks altogether or give yourself a weekly/daily limit. A good alternative is having some fruit infused sparkling water, as a lot of people just crave that fizz and not necessarily the sugar or caffeine in soft drinks

Anyway, what I am getting at, is that most of the current research on diet soft drinks is actually based on surveys or epidemiological research. This is research that tries to find a relationship between 2 things/variables then sets up further studies to find which variable causes what. For example, more often than not, it is the diet in these studies that is not controlled, therefore it is impossible to tell whether it is in fact the diet soft drinks that cause a person to gain weight or just the fact that they are over eating in comparison to someone else.

So, if you are someone who craves a fizzy drink every now and then and have been scared by the media into thinking diet drinks are worse for you, then fear not! A diet drink will have little to no calories, may even suppress your appetite, and of course has no sugar! As the saying goes, everything in moderation so don’t go thinking you can drink endless diet drinks just because there are no calories. You must also remember that there are zero health benefits to drinking soft drinks, hence why they should be limited in your diet.

I personally try to avoid using the terms ‘good’ and ‘bad’ when referring to food and drink with clients because I feel we should never be made feel guilty for eating a certain food or having a glass of wine for example.

The same goes for your children (wine aside). We don’t want to be creating unhealthy associations with certain foods, goodness knows it’s hard enough as it is to get children to eat fruit and veg without scaring the bejesus out of them regarding their favourite beverages.

We should be aiming to eat a nutrition-packed diet that lasts a lifetime, not just this all-or-nothing approach only when we feel we need to lose a few lbs. That means knowing what foods make us feel good, what foods help us perform optimally both mentally and physically, as well as enjoying our favourite foods from time to time that may not be quite as nutritious. I use my Instagram account @caloriesandcarbs to show how I, myself, live by this rule :)


  1. Malik VS, Popkin BM, Bray GA, Despres JP, Willett WC, Hu FB. Sugar-sweetened beverages and risk of metabolic syndrome and type 2 diabetes: a meta-analysis. Diabetes Care. 2010;33:2477-83
  2. Hu FB. Resolved: there is sufficient scientific evidence that decreasing sugar-sweetened beverage consumption will reduce the prevalence of obesity and obesity-related diseases. Obes Rev. 2013;14:606-19
  3. Soffritti M, Belpoggi F, Esposti DD, Lambertini L. Aspartame induces lymphomas and leukaemias in rats.European Journal of Oncology 2005; 10(2):107–116
  4. Williams CL, Strobino BA, Brotanek J Weight control among obese adolescents: a pilot study Int J Food Sci Nutr. (2007)