Does Diet Coke Make You Fat?

Does Diet Coke make you fat?

does diet coke make you fatIn the land of the interweb, memes will tell you that having a drink of Diet Coke is about as bad for you as sticking your tongue in a blender.

And we all know a resident self-appointed “diet expert” – i.e. the girl at your office who doesn’t possess any qualifications but does sneer at other people’s food choices as she chows down on salad so, you know, science – who claims Diet Coke is linked directly to Satan.

Check out this email from website member Suzy:

“Hi Russ, my diet has been progressing well and I’ve lost a total of 24lbs, which I’m really happy with. I’ve always enjoyed a glass of Diet Coke with my lunch and recently a colleague has been giving me the third degree on this, saying I am ruining all my results.

I know I’m not, because I’m still losing weight and seeing progress. But it’s playing on my mind now. She says I need to eat clean and drink only water, otherwise it’s all pointless. I don’t feel the need to diet so hard that I need to avoid everything I enjoy. So can you answer this question once and for all for me?”

So today I’m going to look into this question and get past the BS.

is diet coke bad for you

Does Diet Coke Make You Fat?


Anything with zero calories cannot make you gain weight.

I could end this post here, as it’s simple science, but I’ll go on.

A 2009 study published in the Journal of Endourology concluded that drinking carbonated diet soda drinks is not harmful to health or overall body composition. (1)

Yes, despite the plethora of shock journalism which tells you otherwise, there is absolutely zero evidence to support claims that diet soda is counterproductive to weight loss.

Nor will it slow down your metabolism. (2)

But what about the claims that the sweeteners in Diet Coke and other diet soda drinks will “trick” the body into believing it’s had sugar and spike insulin levels through the roof, causing unnecessary fat storage?

Again, nope. (3, 4, 5)

Despite the scare tactics usually employed by self-proclaimed “wellbeing coaches” looking to sell you their latest detox pack, all relevant scientific data at the moment points clearly towards the fact that the sweeteners found in diet soda drinks are safe unless consumed in ridiculous proportions, meaning that you have absolutely nothing to worry about regarding weight gain or weight loss as a result of having a can of Diet Coke every so often. (6)

So long as your overall diet is still hitting your daily calorie targets, keep focusing on the big picture and you will see results.

Despite the fact that diet soda drinks are often associated with adverse weight issues, this is mainly due to the fact that the bulk of people who consume these beverages are doing so in an attempt to lose weight by chopping calories from their diet, leading to an association that “people who drink diet soda generally have weight issues.”

But correlation does not equal causation.

As you can see, the evidence clearly demonstrates that having a glass of your favourite diet soda will not wreak havoc on your diet. Nor will it force a team of imaginary Oompa Loompas to flip your body’s fat burning switch off and then guard it with their life. Nor will it melt you from the inside out.

So where does the problem lie regarding Diet Coke and weight loss?


does Diet Coke make you fat

The Big Issue

Yep, you guessed it.

When it comes to weight gain and weight loss, the big deciding factor is your overall calorie consumption. And the biggest misconception regarding drinking Diet Coke – and any other diet soda – is that it’s “healthy”.

Make no mistake, it’s not “healthy”.

By that, I mean it’s not something which is going to help you to burn more fat or perform better in the gym.

No, it’s simply a calorie-less drink. That is all.

And by placing yourself under the false idea that you are somehow in a calorie deficit because of this drink, most people fall into the trap of jamming more and more calories into their diet, resulting in weight gain. (7)

You see, a fascinating 2009 study from the University of Texas Health Sciences Center discovered that if we compare diet soda to other calorie-free drinksand controlling the rest of the calorie intakeno difference in weight loss was experienced. (8)

The big issue at hand is the bad habits of the target audience who commonly opt for diet soda drinks, rather than the diet soda itself.

does diet coke make you fat

The Bottom Line

So there you have it.

Drinking a can of Diet Coke will not make you fat, or ruin your hard earned results in the gym.

As for your friend’s recommendation to go down the rigid clean eating route, if you are a regular reader of my blog you’ll already know my opinion on that.

So here’s the deal:

Unless you are taking the absolute piss with your soda consumption – and if you are reading this thinking you are taking the piss, chances are you’re right – the worst you can expect from occasional diet soda consumption is feeling a bit gassy and bloated, and the obvious dental issues which arise. (9)

The body can tolerate everything in moderation, and Diet Coke is no different.

Most of my clients make space in their diet for drinks like this as-and-when they require them, and I see no relevant research currently available presenting a viable reason to change that.

Click here for free access to my workout plans. Thousands of people use them already.


  1. Passman CM, et al. “Effect of soda consumption on urinary stone risk parameters.” J Endourol, 2009.
  2. Maersk M., et al. “Sucrose-sweetened beverages increase fat storage in the liver, muscle, and visceral fat depot: a 6-mo randomized intervention study.” Am J Clin Nutr, 2011.
  3. Møller S. E., et al. “Effect of aspartame and protein, administered in phenylalanine-equivalent doses, on plasma neutral amino acids, aspartate, insulin and glucose in man.” Pharmacol Toxicol, 1991.
  4. Wolf-Novak L.C., et al. “Aspartame ingestion with and without carbohydrate in phenylketonuric and normal subjects: effect on plasma concentrations of amino acids, glucose, and insulin.” Metabolism, 1990.
  5. Horwitz D.L., et al. “Response to single dose of aspartame or saccharin by NIDDM patients.” Diabetes Care, 1988.
  6. Andrew G., et al. “Sweet-taste receptors, low-energy sweeteners, glucose absorption and insulin release.” Br J Nutr, 2010.
  7. Davidson T.L., et al. “A Pavlovian approach to the problem of obesity.” Int J Obes Relat Metab Disord, 2004.
  8. Nettleton J.A., et al. “Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA).” Diabetes Care, 2009.
  9. Shenkin J.D., et al. “Soft drink consumption and caries risk in children and adolescents.” Gen Dent, 2003.

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