Could aspartame prevent weight loss?

aspartame-884051_960_720I’ve never been a fan of artificial sweeteners.  My philosophy about that stuff “It’s not nice to fool Mother Nature”.  Taste buds were meant to sense sweetness from sugars.  Stimulating them with unrelated chemicals sounds like a bad idea to me.  But plenty of people are now dependent on that sweetness fix from manufactured non-caloric sweeteners like saccharine and aspartame.  For years, artificial sweeteners have been pushed marketed as the solution to obesity, although ironically obesity keeps increasing.  Coincidence?

So this headline caught my eye “Can aspartame prevent weight loss?”  Wait, what?  Aspartame was supposed to cause weight loss.  No this is not a typo.  The study examines whether aspartame in fact prevents weight loss.  In other words, it’s not just a study about cutting calories by substituting a non-caloric sweetener for sugar.  The premise is that aspartame actually does something in the body that metabolically interferes with metabolism and weight loss.

The researchers used mice, divided into 4 groups:

  1. chow diet and water
  2. chow diet and aspartame sweetened water
  3. high fat diet and water
  4. high fat diet and aspartame sweetened water

After 18 weeks, the mice were evaluated for a variety of metabolic indicators including:

  • intestinal alkaline phosphatase (IAP) an enzyme found in the intestines that, in normal conditions helps to prevent type 2 diabetes, cardiovascular disease and other problems.  When aspartame is broken down, one by-product is phenylalanine, a known inhibitor of IAP.
  • blood sugar
  • TNF-alpha, a protein involved in inflammation


  1. The mice on the high fat/aspartame diet gained more weight than mice consuming high fat/water diet.
  2. Both aspartame-drinking diet groups had higher blood glucose and higher TNF-alpha levels than the water-drinking mice

The researchers attributed these findings to the sweetener’s interference with IAP activity.  They pointed out that elevated TNF-alpha is characteristic of people with metabolic syndrome.


First it’s a mouse study, so critics can cry “Foul!  These findings don’t apply to humans.”  Maybe.  Maybe not.  It’s certainly interesting though.

Second, the study didn’t look at any effects on calorie intake.  We’re talking about mice after all.  They aren’t likely to put themselves on low calorie diets and stick to reduced calorie intake.  So while aspartame might have some effect on IAP, if use of aspartame reduces calorie intake, a person still could lose weight, or maintain a lower weight after a diet.

Finally, this study was about specific chemical effects of aspartame, not about any other artificial sweeteners in use today.  Aspartame is a unique molecule, so if it’s found to have unique metabolic effects, I’m not surprised.

What should you do?

Well, you could get off the sweet tooth bandwagon and drink plain water or plain tea or unsweetened coffee drinks.  Sweetened beverages don’t contribute anything useful that you can’t find in whole foods.  I remain suspicious about the effect of artificially sweetened beverages and foods on sugar cravings.  And then there’s the obesity evidence.  In all the decades we’ve been guzzling artificially sweetened soft drinks, rates of obesity, type 2 diabetes and metabolic syndrome have exploded.  Artificial sweeteners haven’t helped prevent that.  Why?

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