Zero weight loss from zero calorie drinks? Say it ain’t so – . Health Blog

Are you trying to save calories by switching from regular soda to diet soda? Do you prefer carbonated water with a bit of flavor like Hint or LaCroix? Or did you buy a carbonation device like SodaStream or Drinkmate?

Research suggests that none of these choices can actually help you lose weight. Worse, they could even lead to weight gain! The reason might surprise you. It sure surprised me.

The problem with regular sodas isn't just the calories

If you drink two 12-ounce cans of regular Coke each day, you can eliminate 280 "empty" (non-nutritious) calories by switching to a calorie-free alternative. Over a month, that's 8,400 fewer calories, enough to lose nearly two and a half pounds. So what's the catch?

One concern is that artificially sweetened diet sodas can create cravings for sweet, high-calorie foods. Even if the number of calories from calorie-free soda drops, consuming other foods and beverages can do even more. Rodent studies have found that at least one artificial sweetener (aspartame) damages a part of the brain that tells the animal when to stop eating.

And a number of human studies (like this one and this one) have actually found a weight gain tendency in people who drink artificially sweetened beverages. The research has been inconsistent, however: other studies have shown that artificially sweetened low calorie drinks can help you lose weight.

One factor that makes researching calorie-free beverages and weight loss difficult is called the "reverse cause." People at risk for obesity tend to choose these drinks, which makes it appear that these drinks are to blame.

Of course, there are other health concerns related to artificial sweeteners, including a possible increase in the risk of certain types of cancer, cardiovascular disease, and kidney problems. However, the evidence isn't strong enough to be certain.

Surely carbonated water without artificial sweeteners is okay?

Drinks that contain carbonated water and no artificial sweeteners have long been considered safe bets when it comes to breaking the normal soda habit. How can you go wrong if you don't have sugar, calories, or artificial sweeteners?

But a 2017 study on humans and rats also casts doubt on this approach.

First, the rats: for over a year, male rats were given one of four beverages: water, a normal carbonated drink, a normal carbonated drink that was allowed to go flat, or a carbonated diet drink. The normal carbonated drinks had sweeteners that were not artificial.

Here's what the researchers found:

• The rats that drank a carbonated beverage (regular or diet) ate more food than rats that drank water or flat soda
• The rats that drank a carbonated beverage (regular or diet) gained weight faster than rats that drank water or flat soda
• The amount of ghrelin in gastric tissue after exposure to carbonated beverages was higher than that of non-carbonated beverages. Ghrelin is a hormone that controls hunger.

And now the people: 20 male students drank five drinks, one per session for a month. The beverages included water, regular soda, regular soda that had flattened out, diet soda, or carbonated water. Soon after, her blood ghrelin levels were measured.

When students drank carbonated beverages (regular soda, diet soda, or carbonated water), their ghrelin levels rose to a higher level than when they drank water or flat soda.

Although this study did not evaluate students' food intake or weight changes after drinking different types of beverages, the increased ghrelin levels after consuming carbonated beverages make it plausible that these beverages can lead to hunger, increased food consumption, and weight gain. And that is cause for concern.

Why would drinking carbonated beverages encourage your body to release more ghrelin? The study's authors speculate that pressure-sensitive cells in the stomach respond to the carbon dioxide in carbonated beverages by increasing ghrelin production.

What is left to drink?

The short answer is simple: water. Unsweetened tea or fruit-infused water are also good alternatives.

It should be emphasized that occasionally drinking regular soda or any other carbonated beverage is not dangerous. The question is, what is your default drink of choice – and what are the possible consequences?

The final result

While clear water is the best for health, it is not the most attractive choice for many. If you'd rather drink soda every day, it makes sense to switch from a regular to a calorie-free alternative. A low calorie carbonated drink can still be a sensible choice as long as you keep track of the rest of your diet and weight.

There is a real possibility that carbonated drinks could have a negative effect on appetite and weight. Still, it would be premature to say that we should all cut out carbonated drinks so that the obesity epidemic does not get worse.

Look forward to future research examining the health effects of a range of low calorie beverages. While it is good to make decisions, it is also good to understand the pros and cons of each one.

Follow me on Twitter @RobShmerling