Diet soda and weight gain

I wonder what Seth Roberts thinks about this:

Study links diet soda to weight gain


San Antonio Express-News

A review of 26 years of patient data found that people who drink diet soft drinks were more likely to become overweight.

Not only that, but the more diet sodas they drank, the higher their risk of later becoming overweight or obese — 65 percent more likely for each diet drink per day.

The findings, the latest from the long-term San Antonio Heart Study, took even the researchers by surprise.

”I was baffled,” said Sharon Fowler, a faculty associate at the University of Texas Health Science Center, who presented the data earlier this month at the American Diabetes Association’s 65th annual Scientific Sessions in San Diego.

Researchers looked at questionnaires and medical records for 1,177 patients who began enrolling in the study in 1979. All had weights considered either normal or overweight, but not obese.

The volunteers were asked how many soft drinks per day they usually drank and whether they were regular or diet — or a combination of each. The researchers followed up with them over the years.

Drinking any soda — regular or diet — was linked to a higher risk of becoming overweight and increased incidences of cavities and tooth decay. As any Dentist in Sarasota will agree, consuming sugary drinks in excess can wreak havoc on your teeth and oral health. But when the researchers adjusted the data to account for differences in age, sex and ethnicity, they found that regular soft drinks had very little connection with serious weight gain.

Diet drinks, however, did.

The researchers are quick to point out that their findings are not proof that drinking diet soft drinks causes people to become heavy. It could be that as they began gaining weight, they switched from regular to diet drinks.

”People who were normal weight, one out of four of them at the time of our study were drinking diet drinks,” Fowler said. “People who were overweight but not obese, one out of three of them were drinking the diet drinks. Definitely they were voting with their feet. They were obviously trying to avoid gaining further weight or repeating a family history.”

However, the idea that diet sodas can lead to weight gain isn’t new. Last year, a group from Purdue University found that when rats were fed the equivalent of diet soda, they ate more high-calorie food afterwards than did rats fed the same amount of a drink sweetened with high-calorie sweetener.

Here’s another story with more details, including:

That may be just what happens when we offer our bodies the sweet taste of diet drinks, but give them no calories. Fowler points to a recent study in which feeding artificial sweeteners to rat pups made them crave more calories than animals fed real sugar.

“If you offer your body something that tastes like a lot of calories, but it isn’t there, your body is alerted to the possibility that there is something there and it will search for the calories promised but not delivered,” Fowler says.

This is very similar to the reasoning applied in reverse by Seth, who recommends a weight-loss strategy based on taking sugar water (with calories but no taste) between meals. Seth developed his ideas using self-experimentation but based his conjectures on rat experiments as well.

7 thoughts on “Diet soda and weight gain

  1. Andrew, you're presumably able to get in contact with Seth Roberts, who quite sensibly doesn't appear to publish his email address. Could you pass along an idea for testing one of his hypotheses in a larger sample?

    Following along the link to his webpage, Seth hypothesises that human beings have a circadian rhythm for things like moods and irritability. The idea being that human contact in the morning is good for depression but human contact in the evening is bad. He appears to be testing this by using television-watching as a substitute for human contact; I'm not a psychologist but I'd guess that it isn't.

    If he wants to do an experiment on this, the ideal study group would be the staff of an investment bank. People who work for investment banks on the professional "front office" grades are very similar on broad-brush social indicators, but they divide professionally into two categories; brokers and bankers, who keep very different hours.

    Brokers have lots of human contact in the morning because they have morning meetings an hour before the market opens and do most of their client contact then. Bankers have lots of human contact in the evening because they do a lot of work over dinner and because they stay late to work on deals. This is pretty systematically true across the industry. If there were systematic differences between brokers and bankers on measures of depression (and the folk wisdom of the industry certainly has brokers as cheerful and bankers as miserable) then Seth's hypothesis would be supported.

    sorry to hijack your blog but I did try to get an email address.

  2. I think the researchers' interpretation is reasonable. People who are not gaining weight feel free to drink sugar drinks, which they have been told cause weight gain. People who are gaining weight avoid sugar drinks, drinking diet sodas instead. Several other epidemiological studies have found that the more sugar you eat, the less you weigh — to the researchers' surprise.

    In the last 1980s, Israel Ramirez, a scientist at the Monell Chemical Institute, reviewed the literature about the effects of sugar on weight. He concluded that although sugar under some conditions can cause weight gain in rats, this was apparently because the sugar (which was in water) caused the rats to drink more water.

  3. Very interesting – the major issue I have with this research is that the investigators have done a poor job of constructing a nomological network of any complexity – the research is basically a set of main effects with little by way of blocking – this leads to the standard set of endless hypotheses that really cannot be properly assessed – yes correlation does not imply causation – but it does lead to publications and policy debates that are really left to opinions – I am personally dissappointed in the researchers in this case – they make a mockery of science and statistics

  4. The author seems to forget that genes also have a big role to play in weight gain. What one takes in alone is noe sufficient to account for increase in weight.

  5. I think that there is a similar effect for people that try to stop smoking also, they try to minimize sensual pleasures to avoid the urge to smoke, but then they feel deprived or "starved" for something and the result is more smoking instead of less.

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