Caffeine Makes Us Feel Better

Yet another study shows that people who drink diet soda actually gain weight. But it probably doesn't matter, since that's not why people drink them.

Yet another study shows that people who drink diet soda actually gain weight. But it probably doesn’t matter, since that’s not why people drink them.

Science Daily (“Waistlines in People, Glucose Levels in Mice Hint at Sweeteners’ Effects: Related Studies Point to the Illusion of the Artificial“):

In the constant battle to lose inches or at least stay the same, we reach for the diet soda. Two studies presented June 25 and 27 at the American Diabetes Association’s Scientific Sessions in San Diego suggest this might be self-defeating behavior.

Epidemiologists from the School of Medicine at The University of Texas Health Science Center San Antonio reported data showing that diet soft drink consumption is associated with increased waist circumference in humans, and a second study that found aspartame raised fasting glucose (blood sugar) in diabetes-prone mice.

“Data from this and other prospective studies suggest that the promotion of diet sodas and artificial sweeteners as healthy alternatives may be ill-advised,” said Helen P. Hazuda, Ph.D., professor and chief of the Division of Clinical Epidemiology in the School of Medicine. “They may be free of calories but not of consequences.”

To examine the relationship between diet soft drink consumption and long-term change in waist circumference, the Health Science Center team assessed data from 474 participants in the San Antonio Longitudinal Study of Aging, or SALSA. This is a large, population-based study of the disablement process in elderly Mexican Americans and European Americans. Dr. Hazuda, senior author of the presentation, is SALSA’s principal investigator and has led the study for two decades.

Measures of height, weight, waist circumference and diet soda intake were recorded at SALSA enrollment and at three follow-up exams that took place over the next decade. The average follow-up time was 9.5 years. The researchers compared long-term change in waist circumference for diet soda users versus non-users in all follow-up periods. The results were adjusted for waist circumference, diabetes status, leisure-time physical activity level, neighborhood of residence, age and smoking status at the beginning of each interval, as well as sex, ethnicity and years of education.

Diet soft drink users, as a group, experienced 70 percent greater increases in waist circumference compared with non-users. Frequent users, who said they consumed two or more diet sodas a day, experienced waist circumference increases that were 500 percent greater than those of non-users.

This doesn’t establish causation, however. Indeed, since they don’t appear to have controlled for any other dietary factor other than intake of diet sodas, I’d bet my money that a sweet tooth is the real link.

Still, as Esquire‘s Answer Fella points out (“Why People Really Love Diet Coke So Much“), this may be beside the point.

According to Thomas Critchfield, an Illinois State University professor of psychology and coauthor of a study titled “Caffeine Reinforcement Demonstrated in a Majority of Moderate Caffeine Users,” “Caffeine makes us feel better. Stimulant drugs — including caffeine and close chemical relatives in coffee, tea, and chocolate — tend also to improve the focus of attention and enhance mood. Not only are we awake, but we tend to like the way we feel on caffeine.”

Plus, Critchfield notes, “Caffeine is dependency producing. I imagine that this fact puts little dollar signs in the eyes of beverage manufacturers. One more wrinkle: A handful of studies suggest caffeine may cause us to like the flavor of a beverage more than if the beverage were decaffeinated.”

I actually don’t drink much Diet Coke, using it mostly as a mixer with rum (I recommend Cruzan or Appleton Estate, which I much more flavorful than Bacardi at only a modest premium in price) but the caffeine is the primary reason for indulging in colas on the rare instance I drink them straight. I prefer Diet Mountain Dew to Diet Coke for that purpose. And coffee remains far and away my preferred vehicle for caffeine.

Why “Diet”? Partly for the savings of a few calories. Mostly, though, I find the regular versions too sweet.

FILED UNDER: Health, Science & Technology,
James Joyner
About James Joyner
James Joyner is Professor and Department Head of Security Studies at Marine Corps University's Command and Staff College and a nonresident senior fellow at the Scowcroft Center for Strategy and Security at the Atlantic Council. He's a former Army officer and Desert Storm vet. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. michael reynolds says:

    We had a rather horrifying situation the other day. Don’t read any further unless you’re prepared for some pretty awful stuff.

    I’ll just get it out there: my wife accidentally filled the coffee bin with decaf.

    Lethargy. Mental confusion. Headaches. A desire to grab a chef’s knife and run through the peaceful streets of Irvine stabbing everyone I encountered while howling like an animal. (Granted, I often feel that way, so that may not have been caffeine deprivation. But the headaches: that’s caffeine.)

    Then, the truth dawned on us.

    I’m not ashamed to say that I had tears in my eyes as I opened the Peet’s African Sumatra, and brewed up a pot of the full-strength juice, baby, the real thing.

    Oh yeah. So good. Just the way I like it.

    Mmmm. Let’s make another pot.

  2. Ben Wolf says:

    Myers’ Dark Rum is also a good choice. My girlfriend is definitely a fan of Cruzan; I tend to stick with Captain Morgan’s Private Stock.

  3. john personna says:

    They suggest a feedback between diet sodas and “sweet tooth.” That is, it breaks what should be the natural connection between sweet taste and energy. Without the guarantee that sweets provide energy, the body demands more.

  4. Trumwill says:

    What John Personna says. It’s speculated that the fake-sugar confuses the body on whether or not it’s had sufficient sweetness, and pushes for more.

    I’m not sure whether that’s true or not, but I can say this: Every time I have tried to switch to diet, I find myself constantly hungry and constantly munching. This is at odds with the conventional wisdom that soft drinks do not fill you up. Unless it’s the diet drinks actually making me hungry. Or a combination of both.

    Whatever the case, my substantial weight loss included 3-5 soft drinks a day. A sin tax on them would have been counterproductive, for my purposes anyway.

  5. Trumwill says:

    Woah! Comment editing! Sweet! Good work!

  6. Ben Wolf says:

    Very interesting article in the New York Times, on whether sugar could be considered toxic.

  7. Rob in CT says:

    Crap. I drink 3 diet pepsis a day.