Is soda really that big of a deal when it comes to your body weight?

Posted on January 9, 2013

(Last Updated On: May 20, 2017)

This is part of a series. You’re reading part 1part 2 here, part 3 hereand the series in its entirety is here. 

Let me first be very clear, I am not at all advocating drinking soda or sugary drinks. I’m just going to go over the affect these things have on one’s weight; then we’ll go from there.

Much like diet drinks, soda has quite an alarmist stance too. Is this stance valid?

Since this is primarily mentioned in references to children and adolescents, let’s look there.

Sugar-sweetened beverages and body mass index in children and adolescents: a meta-analysis

This review looked at a bunch of different studies and tried to find the relationship between sugary beverages (SB) and body mass index (BMI).

The conclusion:

“The [review] found that the association between SB consumption and BMI was near zero, based on the current body of scientific evidence.”

Over and over again, there just wasn’t much, if any, affect from sugary beverages on BMI.

So, it seems issues with drinking soda are blown way out of proportion. When you step back, this shouldn’t be surprising. Everyone wants to hang their hat on one thing, but this rarely pans out. I can’t think of one person I’ve had who could say to me, “Yeah, once I took out X food or Y ingredient I lost all the weight I wanted.”

Rather than stop there though, let’s go into more detail by looking at one study from the review that seemed to find the biggest impact.

Effects of Decreasing Sugar-Sweetened Beverage Consumption on Body Weight in Adolescents: A Randomized, Controlled Pilot Study

This is probably the best study from the aforementioned review. The study compared a group who subsitituted non-sugary beverages for sugary beverages, then compared their BMI after about 6 months.

(Here’s the wikipedia for BMI if needed.)

The author’s primary conclusion:

“The net difference, -0.14 (BMI) was not significant overall.”

That is, the group that got rid of their sugary beverage consumption had a lower BMI than the sugary beverage group by .14. Considering most people’s BMI falls somewhere between 20 and 40, .14 is a pretty damn small difference.

This difference was much more noteworthy in children who started overweight / obese. Presumably because these are the types of kids who drink more soda. More on this later.

I want to take this further though. The authors for some reason seem to glance over this statement they made:

“Because each 360-mL (12-fl oz) serving of SSB contains 150 kcal, and total SSB consumption was reduced by 82% in the intervention group, we calculate that BMI decreased on average by 0.26 kg/m2 for every serving per day of SSB that was displaced”

Because the intervention group didn’t completely eliminate their SB consumption, the authors came up with (in my mind) a better indicator of the true BMI difference. For every serving per day of sugary beverages that was removed there was a change in BMI by .26.

Here’s how this works out. The equation for BMI is weight (in kilograms) / (height (in meters) ^2). Or kg / m^2

So, a person who weighs 91kg with a height of 1.94 meters:

91 kg / (1.94^2) = BMI of 24.2

Over the course of roughly 6 months (the length of the study), if you added a serving per day of say, a soda, the BMI would increase to 24.46. Meaning the person’s body weight would be (stay with me, algebra haters),

24.46 = weight (?) / (1.94^2) =>

24.46 * (1.94^2) = 92.1 kg = the person’s weight

Start at 91kg; end at 92.1 kg (if everything else is equal)

Thus, over the course of about 6 months the soda netted a difference of about 2.2 pounds. (92.1 kg – 91 kg.) We’ll say over a year this might equate to 4 or 5 pounds. (Note I’m making an assumption that may be false.)

While this difference certainly isn’t going to prevent childhood obesity, I think it’s a bit more important than the authors let on. Also, if you only look at the fattest kids, this difference becomes a little over 6 pounds. Over a year, maybe 12 pounds. (Again, the reasoning being the most overweight kids tend to consume to most amount of soda to begin with.) This is starting to become more of a factor.

Over the course of an entire childhood this could certainly add up. However, I’m speculating these numbers would hold up. Which brings me to this next study:

A randomized trial of sugar sweetened beverages and adolescent body weight

First, this study basically did the same thing as the last study I just mentioned -substituting non-sugared beverages for sugared ones- but looked at overweight and obese adolescents only. In essence, a lot of the fattest kids of the previous study. The participants where things like decreased soda consumption would have the biggest impact.

Second, this study looked at things for 2 years instead of 6 months.

Next, for all the people who bitch “these studies aren’t recent enough,” well, here’s your recent one. Unfortunately, because it’s so recent, I can’t get the full text. That’s ok though, I only want to bring up one line from the abstract:

“The primary outcome, the change in mean body-mass index (BMI) at 2 years, did not differ significantly between the two groups. At 1 year, however, there were significant between-group differences for changes in BMI (-.57) weight (-1.9kg).”

At one year the difference of about 5 pounds holds up pretty nicely with the projected 5 -12 pound difference I just mentioned in the study before this. It seems whatever difference there is after 6 months might just be maintained to the one year mark. HOWEVER, while there was an initial difference after 1 year in BMI by changing sugar beverage consumption, this effect lessened over time, because there is no difference at two years!

This is really bizarre. I don’t want to spend too much time theorizing on why this happened. My initial reaction is the body is amazing at adjusting things, -often unconsciously- in its intent to maintain bodyweight. Perhaps people unconsciously (or consciously?) eventually started consuming more of other items where the difference became negligible. I don’t know.

What’s important here is saying anything resembling “Soda is the cause for childhood obesity” or  “Just eliminate soda to help obese kids” is patently false. I certainly am not saying soda or sugary drinks aren’t factors, but to single them out is futile.

Rant mode, on

I came across this site when I was researching this: KickTheCan [link no longer exists].

This site lists one of the above studies I just went over as a reason (I assume) to disuade people from drinking soda. The site actually quotes the abstract here, going (bolding mine):

“Among overweight and obese adolescents, the increase in BMI was smaller in the experimental group than in the control group after a 1-year intervention designed to reduce consumption of sugar-sweetened beverages, but not at the 2-year follow-up.”

Apparently they don’t even realize on their website, their website which is designed to disuade soda drinking,  they’ve posted a study contradicting their mission statement. They posted a study saying those who drank soda were no fatter after two years than those who did not. 

(I’m guessing someone was too lazy to read more than a couple of sentences.)

The site quotes another study here saying,

“In a recent (2010) study, it was found that children’s median intake is two sodas per week,”

I don’t even want to look at what study they’re referencing, but two sodas per week? Maybe 300 calories per week is what you’re singling out to turn around the obesity problem? There is another term for worrying about 300 calories per week; it’s called masturbation. You know, you’re throwing your hands around but you’re never really getting anywhere.

Continuing one of the quotes from above (emphasis mine),

“”In a recent (2010) study, it was found that children’s median intake is two sodas per week, with a mean of six per week.”

AH! Now we’re getting somewhere. For the non-statistically inclined, means (averages) and medians have a very subtle, but very important, difference.

A mean is susceptible to outliers -those who stand way out of the pack-  medians are not. For example, take 10 people and look at their mean income. If Warren Buffett is part of these 10, the mean is going to be very, very high. Take the median though and Warren Buffett has no greater impact on the data than the other 9. Medians are almost always more accurate of a population.

Bringing me back to my long-winded point: Your median person (or adolescent in this instance) does not have much of an issue with soda or sugary drinks. Abolishing these things is unlikely to have much of an impact on your everyday person or kid. However, if the person is someone who consumes a lot of soda, then we’re likely to see an impact.

That last sentence should read as “No shit.” Yet how many people do you know decrying soda is bad for everyone? Are you sure you’ve never been one of those people yourself? How many weight-loss coaches or dietitians immediately tell people no more soda, ever? Maybe now you understand why your diet of just eliminating soda has failed, over and over again.

Said another way: Your kid consuming too much soda is likely not why he or she (or you) is overweight or obese. It might be part of the equation, but only a part.

Another quote from this “wonderful” website:

“When it comes to childhood obesity, parents certainly have a big role to play. But parents also face the biggest challenge, because sodas are available everywhere and the industry spends more than one million dollars every day marketing their sugar water to kids. Parents don’t stock the shelves in the corner store their kids visit on the way home from school. And parents can’t monitor every website or text message soda companies send to their kid’s phones. Soda companies must stop undermining parents with their aggressive marketing.”

Actually, many parents do stock the corner store. Unless every person of every corner / grocery / food store is not a parent.

And who are the people doing the marketing? The kids?

“Well, they have to make a living” you say. Exactly.

I’m sure parents don’t give their kids the money to buy anything at the corner store either. Oh, wait…This is America and 8 year olds aren’t in sweat shops.

One of the studies stated 50% of sugared beverages were consumed at home.


You know, that place the parents live. Where they bring in the groceries. The groceries the parents bought. 

When you’re blaming 8 year olds for their own health issues you’ve hit the ceiling of ignorance.

And really, Coca Cola is sending text messages to kid’s phones trying to get them to drink soda??? Does this seriously happen? If it does happen, who at Coca Cola is sending the messages? More 8 year olds?

Or how about websites? Because social media has proven to be a terrible way to get people to drink soda. (An interesting aside: I have 13 friends who like Coca Cola on facebook; 8 of them are skinny.)

No, children’s free will isn’t the reason they’re overweight. Coca Cola isn’t the reason either.

The reason they’re overweight is due to all the shit you put in their mouth. You, the parent(s). THE SHIT THEY’RE EATING RIGHT WITH YOUR OVERWEIGHT ASS!

(This is not meant to criticize those who are overweight; this is meant to criticize self-delusion.)

Rant over.

With all that said, what if soda IS a problem for you?

Part 2 here: What’s up with diet drinks and your appetite?



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