We have been taught that there is nothing more to weight loss than calories in vs. calories out.
If this is the case, diet soft drinks must be a great replacement for calorie dense sugary drinks. The diet drinks are calorie free and should therefore help us lose weight.
It’s true, kind of. In the context of a calorie controlled diet, diet soda will not have any significant effect on body weight.
But the fact is that most people do not count calories and just eat when they’re hungry. This is where the situation gets complicated with diet sodas.
There are areas in the brain that control our food intake that don’t have much to do with willpower. These brain centers tell us when we’re hungry and when we’re full, and it just so happens that the food we eat can drastically affect those areas in the brain.
Foods that are very sweet, like sugar and artificial sweeteners, can directly affect those brain centers to make us want to eat more food and accumulate more fat .
This may seem strange, but there is actually a lot of epidemiological evidence showing that diet soft drink consumption correlates with several serious diseases, including (ironically) obesity.
Diet Soda And Food Intake
In a few short-term feeding trials where people eat until fullness, drinking diet soda with a meal leads to increased food intake compared to water. In some cases, the diet soda groups even eat more total calories than the groups who drink sugary soda  .
Diet Soda And Weight Gain
A study performed at the university of Texas discovered that those who drank artificially sweetened beverages increased their BMI by 47% compared to nonusers and had almost a double risk of becoming overweight or obese .
To be fair, one controlled trial found that substituting diet drinks for sugary drinks resulted in a mild decrease in body weight .
Diet Soda And Premature Delivery
A study of 59 thousand women in Denmark discovered that diet soda increased the risk of preterm delivery by as much as 78% for 4 servings per day, indicating that pregnant women should limit their intake .
Diet Soda And The Metabolic Syndrome
The metabolic syndrome is a term which encompasses the basic symptoms of the diseases of affluence, including high blood pressure, elevated cholesterol, weight gain, insulin resistance and a few others. Basically, what is making all the western nations fat and sick.
It turns out that diet soft drinks increased the risk of developing the metabolic syndrome by 34% in a study of 9514 individuals, over a 9 year period .
Diet Soda And Type II Diabetes
Type II diabetes is a disease that has reached epidemic proportions in the last few decades. This serious illness now affects about 300 million people, worldwide.
One study followed 6814 elderly individuals for several years. Daily consumption of diet soft drinks increased the risk of the metabolic syndrome by 36% and type II diabetes by 67% .
Correlation is Not Causation
I’d like to point out that most of these studies are epidemiological in nature. These studies follow a group of people for a certain amount of time and pay attention to whether a certain behavior (like eating a particular food) leads to disease over time.
It is impossible to prove that one thing causes another in such studies but they are useful to give us an idea of things to research further.
There is a possibility that those who have a genetic propensity towards weight gain are more likely to turn to diet soft drinks.
The problem is that the large-scale, controlled trials have not been performed. Until then, my recommendation is to be careful with diet soft drinks, as well as artificial sweeteners in general.
It is true that there isn’t any cold hard evidence to associate artificial sweeteners with any disease, but they haven’t been proven safe either. This is why I recommend that people stick to plain water.
Everyone needs to make up their own mind whether the benefits outweigh the possible risks, but my personal view on any artificial chemical entering the human body is: “Guilty until proven innocent.“