How much is your cola really costing you?


It is a known fact that regular soft drinks are bad for our health. Numerous studies have been done on this hot topic and it’s proven that they are good for nothing.

They are empty calorie (no nutritional value) and the energy intake can increase your daily calorie consumption dramatically because of their high sugar content.

Some of the major health problems include:

  • Decreased metabolism.
  • Diabetes
  • Cardiovascular problems
  • Metabolic syndrome (a collection of three or more of the following).
  1. Central obesity
  2. Elevated blood pressure
  3. Elevated blood triglycerides
  4. Low HDL/High LDL
  5. Insulin resistance
  6. Obesity

It appears that we are doing the right thing by shying away from all the sugary stuff and if you already don’t, I highly recommend you do because the effects will catch up to you sooner or later. And science has proven that.

BUT, what about the zero sugar variety?

I get asked this almost every single day.

As a diabetes educator and a personal trainer, this is a topic of conversation at almost all my education sessions. There is a lot of confusion around this subject as a lot of health professionals recommend their intake over the full sugar varieties, while others claim it is loaded with chemicals and should be avoided at all costs.

So, what’s the scientific truth behind this? Let’s find out!

Below, I discuss some of the myths around diet soda consumption and compare them with the evidence that’s available. 

Diet soda causes weight gain

If we look at it from the calorie point of view alone, diet beverages help reduce sugar intake massively, reducing the daily calorie intake which helps with weight loss.                             

Additionally, in a groundbreaking study on evaluating the use of artificial sweeteners versus just water when attempting to lose weight, the researchers revealed that consumption of artificial sweeteners was actually associated with greater weight loss and a greater ability to keep the weight off after the diet (1).

Despite this simple logic and scientific evidence mentioned above, many people view them as being unhealthy. A lot of the blame seems to be put on the artificial sweeteners.

There is very limited researches done on effects of artificial sweeteners on human subjects. A weak data indicating consumption of diet soda daily (note: daily not occasionally) was associated with significantly greater risk of metabolic syndrome components and type 2 diabetes (2,3).

However, if we dig into the details, the study also found associations with the consumption of a western dietary pattern, such as meat and fried foods promotes the incidence of central obesity and diabetes.

Even though there is a relationship between artificial sweeteners intake and obesity, it is not a direct relationship. In the world of research and science, these studies are often ignored and not used as evidence base.

Diet soda causes cancer

While in one negative research, there was a link found between artificial sweetener (aspartame) dosage and cancer in mice, these researches are done at astronomical amounts equivalent to almost 200 cans of diet soda per day (4). For this reason, they are far from realistic as it would be nearly impossible for a human to consume similar ratio of aspartame in the real world.

Another problem with these studies is that they are mostly performed on rats and we all know that the effects of substances vary greatly when given to humans compared to rats (2).

It would take an astronomical amount of the sweeteners to cause the same effect in humans. In fact, a large systematic review that analyzed 599,741 humans found that even though there were indications that heavy prolonged consumption might increase risk of certain cancers, the evidence was inconclusive. Again this does not mean we cannot enjoy an occasional diet soda (9). 

Diet sodas cause insulin spikes

Many people still insist that artificial sweeteners induce an insulin spike. Insulin spikes can lead to a metabolic disorder called insulin resistance, which means that insulin isn’t able to do its job of removing glucose from the blood. This can lead to further diseases like diabetes and obesity.

Unfortunately for advocates of this theory, research has determined that artificial sweeteners such as aspartame don’t induce an insulin spike, despite claims.

Even if they did, a small insulin spike would not match that of an insulin spike from regular sugar, soda, ice cream, pizza etc. It’s these foods consumed over years which causes weight gain and insulin resistance, not sweetener or diet soda (5,6,7,8).

Take home message?

Firstly, there’s not any strong research in a controlled setting to show ill health from a moderate dose of artificial sweeteners in humans.

There are a lot of false and misleading information out there and a lot of videos done by the clean eating health gurus that always go viral, but that doesn’t mean the information provided is true.

Of course, I am always the first to say we should focus on natural whole foods 90% of the time, but drinking the odd diet soda is also perfectly fine.

To make it clear, I am absolutely not encouraging you to pick diet sodas over water but equally you should not have to stop consuming it occasionally if you enjoy it.

It depends on you. If you love it, it may aid your journey to a better health through weight loss and sustainability and also hydrate you (remember, it’s mostly water).

In summary, diet soda or artificial sweeteners are perfectly ok in a moderate dose. There is no research to prove it otherwise. 


  1. Peters, J. C., Beck, J., Cardel, M., Wyatt, H. R., Foster, G. D., Pan, Z., ... & Hill, J. O. (2016). The effects of water and non‐nutritive sweetened beverages on weight loss and weight maintenance: A randomized clinical trial. Obesity24(2), 297-304.
  2. Lutsey, P. L., Steffen, L. M., & Stevens, J. (2008). Dietary intake and the development of the metabolic syndrome. Circulation117(6), 754-761.
  3. Nettleton, J. A., Lutsey, P. L., Wang, Y., Lima, J. A., Michos, E. D., & Jacobs, D. R. (2009). Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA). Diabetes care32(4), 688-694.
  4. National Toxicology Program. (2005). NTP report on the toxicology studies of aspartame (CAS No. 22839-47-0) in genetically modified (FVB Tg. AC hemizygous) and B6. 129-Cdkn2atm1Rdp (N2) deficient mice and carcinogenicity studies of aspartame in genetically modified [B6. 129-Trp53tm1Brd (N5) haploinsufficient] mice (feed studies). National Toxicology Program genetically modified model report, (1), 1.
  5. Møller, S. E. (1991). Effect of Aspartame and Protein, Administered in Phenylalanine‐Equivalent Doses, on Plasma Neutral Amino Acids, Aspartate, Insulin and Glucose in Man. Basic & Clinical Pharmacology & Toxicology68(5), 408-412.
  6. Wolf-Novak, L. C., Stagink, L. D., Brummel, M. C., Persoon, T. J., Filer, L. J., Bell, E. F., ... & Krause, W. L. (1990). Aspartame ingestion with and without carbohydrate in phenylketonuric and normal subjects: effect on plasma concentrations of amino acids, glucose, and insulin. Metabolism39(4), 391-396.
  7. Horwitz, D. L., McLane, M., & Kobe, P. (1988). Response to single dose of aspartame or saccharin by NIDDM patients. Diabetes care11(3), 230-234.
  8. Teff, K. L., Devine, J., & Engelman, K. (1995). Sweet taste: effect on cephalic phase insulin release in men. Physiology & Behavior57(6), 1089-1095.
  9. Mishra, A., Ahmed, K., Froghi, S., & Dasgupta, P. (2015). Systematic review of the relationship between artificial sweetener consumption and cancer in humans: analysis of 599,741 participants. International journal of clinical practice69(12), 1418-1426.