What’s up with diet drinks and appetite?

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This is part of a series. Part 1 here, you’re reading part 2, part 3 here, and the series in its entirety is here. 

Diet drinks get chastised all over the place. I’m going to go over some of the more prevalent reasons, at least from what I’ve seen.

One of the main arguments against diet drinks is they increase appetite. The main tenet of this argument seems to be artificial sweeteners are sweet, so they cause sweet cravings.

I’m going to ignore the fact I’ve never heard someone go, “Yeah, you know, whenever I’m craving chocolate I’ll eat chocolate, and then my craving gets worse. Next thing I know the only thing I’m eating is chocolate 24/7.”

Or “Yeah, I was just chomping at the bit for a cheeseburger so I entered one of those pound burgers challenges and you know what? All it did was make me go and order more burgers!”

I’m pretty sure people typically eat a particular food to mitigate a craving; not exacerbate it, but let’s throw silly logic aside for now.

Back to the original argument: While you may get rid of the calories from say, a Coke, by drinking a 0 calorie Diet Coke, you’re still not going to get anywhere. You may actually go backwards due to the diet drink increasing your appetite.

First, and I can’t believe I even have to address this, but there are people who go “Aritificial sweetener use has increased in the last 40 years and so has obesity. Thus, increased artificial sweetener use leads to eating more, which leads to obesity.” When attempting to describe the rage instilled in me upon hearing things like this the only words that come to mind are, “Dexter.”

Let’s take a look at some research.

Satiety scores and satiety hormone response after sucrose-sweetened soft drink compared with isocaloric semi-skimmed milk and with non-caloric soft drink: a controlled trial.

In this study a few different drinks and their affect on hunger were looked at. How much people ate after they had each drink was looked at too. The drinks were a regular soda, skim milk, aspartame (artificial sweetener found in things like Coca Cola) drink, and water.

Soda increased hunger the most, milk was second, and then water and artificial sweetener were tied for the least.

Summarizing from the author in an interview with NPR,

“We found if you’re drinking soft drinks without calories it behaves [on the appetite] exactly like drinking water”

And then from the actual study:

“Furthermore, there were no indications [diet soda] increased appetite or energy intake compared with water.”

Another study finding no evidence is The Use of Low-Calorie Sweeteners by Adults: Impact on Weight Management

One quote from that paper:

“Although reported consumption of carbonated soft drinks and fruit juice, 2 of the most frequently consumed food categories, has declined over the past decade”

For all those who love correlation, there you go. According to this, in the last 10 years people have gotten fatter, but soft drink consumption has gone down. Riddle me that, Ms. Kick The Can.

There’s also this from Nonnutritive sweetener consumption in humans: effects on appetite and food intake and their putative mechanisms 

“Overall, only 15.1% of all Americans indicated that they consumed any food or beverage with NNS added in 2003–2004”

66% of people are overweight / obese, but only 15% consume artificial sweeteners. Only adding to the case for artificial sweeteners not having much, if any, impact on people being overweight.

Sucrose compared with artificial sweetener – different effects on ad libitum food intake and body weight after 10 weeks of supplementation in overweight subjects

In this study a group of overweight people, primarily women, were given one of two supplements. One essentially a sugar drink; the other an artificially sweetened drink. Basically one sweet drink with calories and one sweet drink without calories.

The result:

“Records of ad libitum [unrestricted] food intake (including supplements) showed that total energy intake increased significantly in the sucrose group (by 1.5 MJ/d) but remained constant in the sweetener group compared with habitual energy intake (Week 0.) “

Other than carbohydrates and sugar, nutrient consumption stayed pretty much the same between groups.

The most noteworthy thing from this study is the group who was given more sugar to drink consumed…more sugar (and carbs). Thus, they gained weight. In comparison to the artificial sweetener group which actually lost some weight.

“Body weight and fat mass increased in the sucrose group and decreased in the sweetener group during the 10-wk intervention. For the sucrose group, the total weight gain at week 10 averaged 1.6 kg, of which 1.3 kg was a gain in fat mass. For the sweetener group, the total weight loss at week 10 averaged 1.0 kg, of which 0.7 kg was fat-free-mass and 0.3 kg was fat mass. “

The artificial sweetener group improved in just about everything. Likely due to the fact they lost weight as opposed to the sweetener doing anything physiologically.

(Click to enlarge.)

Another anecdote: In the group given the sugar supplement, while there overall sugar and carbohydrate consumption increased, they decreased their original consumption of sugar. For example, say a person consumed 100 grams of carbs a day from three different foods before the intervention. After the intervention they may have decreased their consumption to 50 grams a day from those three foods, but overall increased the consumption to 150 grams due to the supplementation scheme.

This makes sense. The body is trying to make some adjustments and not just increase everything.

What’s interesting here is this: The artificial sweetener group ALSO decreased their sugar and carbohydrate consumption. As if the artificial sweetener acted in the brain just like the sugar supplement did. So, if the artificial sweetener isn’t doing anything physiologically, it could very well be doing something psychologically. (Although, maybe you can’t really separate the two.) The significance being the artificial sweetener has much less, if any calories associated with it. Hence, sweetener group loses weight; sugar group gains weight.

(Remember, in this study people didn’t know what they were consuming.)

Lastly, again, the artificial sweetener group suffered no negative influences on their appetite. If anything, they received a benefit.

Oh, and just to throw it out there. The sweetener group, again the group that lost weight, consumed more alcohol than the group that gained weight. No surprise there. 

Summarizing appetite effects

Overall, it appears diet drinks or artificial sweeteners really have no impact on appetite. Anyone who quotes a study saying they do can easily be refuted by a study saying they don’t. Hell, some studies say they decrease hunger.

I also want to bring up for the studies that do find an increase in hunger, the reasoning seems to be this: Whenever an artificial sweetener increases hunger it seems to be when it is consumed by itself, in a form similar to regular eating (like drinking a diet drink). However, consume the diet drink with other food, and this effect, if it was even there to begin with, goes away.

There are even studies out there where people were given the sweetener in pill form and this result of increased hunger goes away. Further indicating it’s not the sweetener but the act of drinking that may be bringing on the hunger.

This is discussed nicely in Nonnutritive sweetener consumption in humans: effects on appetite and food intake and their putative mechanisms.

This is a good time to apply all this research to the real world. And in reality hunger is an extremely complicated area. Another quote from one of the above studies (bolding mine):

“It is clear that low energy sweeteners can be as satisfying as sugars during a meal, particularly when subjects are unaware of the caloric manipulation.”  

When they are unaware.

Here’s a big issue with this body of research: In the majority of research a double blinded study is ideal. However, in reality, people know what they’re eating. They know if they switched to diet, or a low-fat alternative. And because they know, they can consciously or unconsciously compensate.

A similarity would be exercise: People know they exercised on a particular day; because of this some are likely to go to McDonald’s as a “reward” where others are going to want to eat very “clean” that day to not mess up their great workout. Psychology is profound in influencing appetite.

For instance, if you’re someone who only has a can of diet coke when eating lunch, it’s easily conceivable drinking a diet soda is going to trigger hunger as your body is used to the association of soda = meal time.

Or here’s a quick blurb how the color of a cup of hot chocolate affects satisfaction: http://www.businessinsider.com/color-of-containers-affect-taste-2013-1

Or the fact often times people switch to a “diet” or “low-fat” food but then immediately compensate by eating more calories from the low-fat option than they would have eaten of the original. In my post on Mindless Eating (here and here) I talk about how those given a “low-fat” granola bar end up eating more overall than the “regular” granola bar group. The theory being people subconsciously go, “Well, I had a low-fat snack, now I can eat more of other things.”

At this juncture, a bunch of people are thinking, “Ok, but what about the health concerns of artificially sweeteners themselves? I get they can help me lose weight, but won’t they cause cancer in the process? I’d rather be fat without cancer than skinny with tumors.”

Part 3 here: Are diet drinks safe? Do artificial sweeteners really cause cancer?