Does Diet Soda Cause Weight Gain Feature Image

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The thought of indulging in your favorite carbonated beverage may be put to one side while trying to lose weight, but diet sodas are a popular option with those trying to cut calories for weight loss.

Some people, however, claim that drinking diet soda causes weight gain – the polar opposite of what consumers hope for.

We take a look at both sides of the argument to answer the question, “does diet soda cause weight gain”?


People may think that just because a drink has no calories, it will help you lose weight. However, there are several reasons why diet soda may cause the body to retain or gain weight. Sodas usually contain sodium, which is notorious for causing water retention.

If you drink diet soda you are probably holding onto excess water weight that could be lost by switching to consuming water instead of carbonated beverages. In addition to sodium, diet sodas contain a lot of artificial sweetener which can be up to 200 times sweeter than sugar.

This may be better than consuming sugar but the sweet taste can make you predisposed to choosing sweet options at other times, increasing the potential for picking high-calorie foods with little nutritional value.

This could be due to the sweetness receptors that are activated in the brain after consuming diet soda – the brain is tricked into expecting an influx of calories, which the body will then crave when it doesn’t receive them.

The body may also have an insulin response after consuming sweet diet sodas in anticipation of the increased blood sugar levels – over time this process can lead to insulin resistance which can cause weight gain.

One 2014 study found a link between artificial sweeteners and glucose intolerance; the evidence is currently fairly thin, but it is something to consider when choosing your drinks [1].

The last way that diet sodas may cause weight gain is by people using them as an excuse to eat higher calorie foods later on.

Some studies have found that people who drink diet sodas are more likely to consume more snack foods, although it is uncertain whether drinking soda causes this, or whether it is just part of a related behavior pattern.


What causes weight gain is simply consuming more calories than you burn, so consuming beverages with zero calories will not make you gain weight.

In contrast choosing a diet soda over a soda with sugar can save up to 150 calories per can, which can help with weight loss as part of a calorie controlled diet. To put it another way, if you drink one can of regular soda per day then by swapping to a diet soda you could lose a pound per month (12 pounds per year) without doing anything else.

Another way that diet sodas can help with healthy weight maintenance or weight loss is by creating a feeling of fullness due to the carbonation. Often, diet sodas are viewed as de facto appetite suppressants. Furthermore, they can help prevent dehydration disguised as hunger.

The research that has found links between diet soda and weight gain does not prove causality – that is, although some people will drink diet soda and gain weight, there is no evidence to suggest that this is because of the soda. It could because they are predisposed to snack and convenience foods, which are often sold alongside sodas and are typically high in fat, sugar and calories.

Health considerations that should be taken into account when drinking diet soda include dental health due to acids and colorings added to diet sodas, and the amount of caffeine that can be consumed. However, recent fears about diet sodas leeching calcium from the bones are true only for cola drinks due to the phosphorus in the recipes – other diet soda drinks do not have the same effect on the calcium in our bodies.

If in doubt, plain water is always a good option!


There is no solid evidence to suggest that diet soda causes weight gain, and the logic that weight gain only happens when calories consumed exceed calories burned leads to the conclusion that consuming diet soda in itself cannot cause weight gain.

Behaviors such as excessive snacking, consuming a lot of processed convenience foods and not drinking enough can lead to retaining water weight and gaining fat, and is not conducive to building lean muscle.

Rather than rely on any one food or drink item to help you lose weight, take up a regular exercise plan and embark on a diet of healthy, balanced meals that is high in vegetables. Speak to your physician before making any changes to your diet or exercise routine.

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Fact Checked

This article has been reviewed and fact-checked by a certified nutritionist, and only uses information from credible academic sources.