The answer is yes and no, and varies person to person. So if you regularly drink diet drinks - this is a good read for you!
Whilst diet drinks such as Diet Coke, Coke Zero, Pepsi Max, 7upZero, Fanta Zero etc have very low (less than 5) calories or zero calories per serving, they contain artificial sugars such as sucralose, aspartame, acesulfame K and saccharin which have been shown to increase appetite when digested, potentially leading to you eating more.
Ever had a diet drink and then felt hungry afterwards? It's a very common occurrence and numerous studies have shown that calorie consumption goes up after consuming diet drinks. Here's an example of that research which builds on an already quite considerable stack of evidence that points to higher calorie intake in those that regularly consume diet drinks. Sounds counter-intuitive, right?
On the flip side of that, many people find that consuming a fizzy drink helps them feel full due to the gassy nature of the liquid and stops them from consuming more calories. For some, it can also help satisfy sweet cravings and stop further calorie consumption.
In this post, we look at the physiological response to consuming diet drinks and why it might be harmful to losing weight, the pros and cons of including them in your diet, and alternatives that might be helpful and that will lead to better weight loss results.
What is a Diet Drink?
A diet drink is a drink that is created to be either ultra low or zero in calories, typically by using artificial sweeteners or natural sweeteners as opposed to sugar.
These drinks are often marketed by the big food and drink companies as positive alternatives to sugary drinks, especially for those looking to reduce their calorie intake or lose weight.
Diet drinks come in various forms, including fizzy soft drinks (e.g. Diet Coke, Pepsi Max, Coke Zero, 7Up Zero etc), flavored water (e.g. Vitamin Water, Oasis Zero), iced teas, energy drinks (Lucozade Zero), and powdered mixes or concentrates that can be added to water. They are designed to provide a sweet taste without the high caloric content of traditional sugary drinks.
Common artificial sweeteners used in diet drinks include aspartame, sucralose, and saccharin. These sweeteners are significantly sweeter than sugar, meaning drink companies can create low-calorie or calorie-free beverages while still providing a sweet taste.
But what's the catch?
Does Drinking Diet Drinks Mean You Consume Less Calories?
This is one of many questions where the jury is out.
On a strict side by side comparison, consuming diet drinks vs regular drinks means that you'll consume fewer calories.
Examples
Diet Coke | Regular Coke | |
Calories per 330ml Can | 1 | 139 |
Pepsi Max | Regular Pepsi | |
Calories per 330ml Can | 1 | 141 |
There is no doubt that Diet Drinks contain fewer calories than their regular counterparts however, whilst you consume less calories via the drink, there is evidence to suggest that when drinking diet drinks, you consume more calories through food afterwards.
This is due to your bodies physiological reaction to consuming artificial sweeteners.
Your Body's Response to Diet Drinks
Increased Hunger After Consuming Diet Drinks
Some studies have shown that calorie intake from food sources increases after consuming diet drinks. One reason put forward for this is that the artificial sweeteners cause the body to think that it is going to be taking in energy (i.e. sugar), but when it doesn't get the energy it expected hunger hormones signal to effectively put the call out for more food. This can cause you to eat more and, according to research, sometimes significantly more than what you might have eaten if you had not had the diet drink.
Increased Sweet Cravings After Consuming Diet Drinks
The sweet taste of diet drinks can cause people who are susceptible to sweet/sugar cravings to want more, leading to further calorie intake.
The opposing argument to this is that the sweet nature of the drinks can actually help some people satisfy their sugar cravings and stop them from reaching for sugary foods.
Insulin Sensitivity and Metabolism
Insulin sensitivity is a very interesting topic. We won't go in to lots of detail here as we'll write a full article about it, but the important thing to understand is that you want your body to be as insulin sensitive as possible, and NOT insulin resistant.
There is research to suggest that diet drinks increase insulin resistance over time because the artificial sweeteners used in the drinks can stimulate a similar physiological response to consuming real sugar. There is also the suggestion that consumption of diet drinks may effect the bodies ability to metabolise glucose.
The body of research on this subject however is not conclusive, and so it's difficult to say for certain what effects, if any, diet drinks may have on insulin sensitivity and metabolism.
Gut Health
Another argument against diet drinks is that artificial sweeteners can change or damage the good bacteria in your stomach or change the gut microbiome which can then lead to a deterioration of gut health. Again though, the research on this is not conclusive and further studies are required.
Do Artificial Sweeteners Cause Cancer?
At present (May 2024) there is no conclusive evidence to suggest that artificial sweeteners, consumed within the recommended limits, can cause cancer. However, there once was a time when smoking was promoted as healthy.
Food and drink products have to pass rigorous testing and oversight in Western countries e.g. the Food and Drug Administration in the USA or the Food Standards Agency in the UK.
And so you would think that if the drinks have made it through this testing then they should be safe. However, and not to sound like conspiracy theorists, the sponsors of the research being carried out and the influence of large private businesses on government decision making can be huge and so it's unlikely that we have full transparency as to any and all potential effects of regular diet drink consumption.
Looking at diet drinks objectively, it's hard to think that the regular consumption of artificial sweeteners alongside the unnatural flavourings and additives that are included in the recipes is going to be something that is good for you either short or long term.
Why Is There So Much Conflicting Evidence On Whether Diet Drinks Help You Lose Weight?
The simple answer is that it's very difficult to isolate just diet drinks as the main cause of something occurring in the body. Typically, there are many other factors to consider across diet, fitness, health, psychology and environment that can have an impact on how your body might respond after consuming diet drinks. And so it's hard to pinpoint if it's the diet drink that is causing something to happen or is it a myriad of factors.
As an example, a couple of studies have suggested that obese people eat more when consuming diet drinks but those of a healthy weight do not. So is it diet drinks making people obese? Or is it the overall diet, fitness routine and current health of the obese that effects the results? This is why there is a lot of conflicting or inclusive research on whether diet drinks can help you lose weight and/or what effects they have on the body.
Action Points
Start Tracking Food /Drink Intake
If you currently consume diet / zero calorie drinks as a regular part of your diet then the first thing we'd recommend doing is monitoring your food and drink intake. Do this for all times of day.
Keep a food journal or log everything through MyFitnessPal. This way, you can get an accurate idea of what you are consuming on days when you have diet drinks vs days that you don't.
You can then use that data to determine if the diet drinks are having a negative effect on your appetite and causing you to consume more.
If you notice that on days when you consume the diet drinks your calorie intake is much higher then take them out. But if you notice no considerable change then you're probably ok to leave them in as part of your diet.
Monitor Hunger Levels
Something else to note is that if you're actively trying to lose weight or body fat and you're consuming diet drinks and noticing that it's increasing your appetite and hunger, then it may be worth removing them all together.
Even if you're not actually consuming more calories after consuming the drinks, if it's causing your appetite to go up and you're then having to fight feelings of hunger regularly then it will make the weight loss / fat loss journey much harder than it needs to be. By removing the diet drinks, you can remove the stimulus that's making you hungry and make the weight loss journey a lot smoother.
Alternative Drinks to Consider to Help You Lose Weight
Water! At least 3 litres every day and 4-5 litres if you're training.
Water is the drink of adults. Get plenty of water in and you'll feel so much better as well as having many of your cravings for fizzy drinks or flavoured drinks fall away.
Apologies if you were expecting a long list of substitutes. Drink water.
Conclusion
It's important to note that everyone is different. The effect that diet drinks have on you and your appetite, your food consumption and how you feel day to day can vary greatly from the next person. So you need to understand the effects of diet drinks on your body, regardless of what articles, research and studies might suggest.
It's also important to consider the context of diet drinks within your overall diet, health and lifestyle factors. We would argue that for most people, diet drinks make up a relatively small proportion of their overall health and fitness considerations and it would be far more beneficial to focus on getting your overall diet right, ensuring you exercise regularly and doing your best to get plenty of good quality sleep, manage stress and look after your gut health.
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