Is Pepsi Max bad for your weight?
Can artificial sweeteners from diet sodas affect your weight? My six hour experiment the other day implies that the answer might be yes.
The results can be seen above. I drank the Pepsi Max (17 oz.) after about an hour. The black line is the blood sugar and the purple line is the ketones.
Preparation
When the experiment started I was in pronounced ketosis since several weeks (due to a strict LCHF diet). I was fasting six hours before the experiment started.
The first four blood samples were taken before I started drinking Pepsi Max. Blood sugar and ketones were both a bit above 4 mmol/L (which equals a blood sugar of 72 mg/dl). The small variation in the first tests is probably due to the meter not being more exact (normal for home meters).
During the dark mark I drank the Pepsi (50 cl / 17 oz.), it took 10-15 minutes.
Blood glucose results
As you can see nothing special happened to my blood sugar during the experiment. It stayed at around 4,5 mmol/L (80 mg/dl) and the tiny variation is probably within the margin of error of the meter.
Ketone results
If nothing happened to my blood sugar the effect on my ketone levels were more dramatic. As I noted when planning the experiment one of my suspicions were that the artificial sweeteners might trigger a release of insulin. That would lower ketone levels, as ketones are very sensitive to insulin.
Fifteen minutes after drinking the Pepsi my ketone level appeared to drop, from around 4 to 3,4 mmol/L. Then it continued down during two and a half hours until it had dropped by almost 50 percent.
After that the ketone level started rising again. But when I stopped the experiment, almost five hours after drinking the soda, it was still not back where it had started.
What does this mean?
Pepsi Max and other products with artificial sweeteners are thought not to affect peoples weight, as they contain no calories. That’s an oversimplification that ignores any hormonal effects and resulting hunger. If the sweeteners slow your fat burning and increase your hunger they will of course affect your weight – calories or not.
What is clear from the experiment is that something happened. The ketone level dropped precipitously. My interpretation is that this potentially could result in a decreased fat burning, making it harder to lose weight. Perhaps this is due to insulin release, perhaps not.
I wonder: What if your fat burning is impaired for more than five hours, every time you ingest artificial sweeteners?
One objection: Was the culprit the artificial sweeteners or the caffeine in the soda? This experiment can’t tell, but I would gladly bet money on the sweeteners. Perhaps I’ll do a similar experiment later, drinking black coffee instead.
What do you think about the results?
138 comments
Remember that you don't have to give up everything at once. Why not keep drinking the diet pepsi for a little while longer and see you you feel a few weeks from now?
In my opinion, "giving up" foods/drinks isn't what you do on low-carb. On low-carb you build strong, healthy eating habits, and sometimes you make exception to these habits :) Personally, I have 2-3 beers around two times a month. I know that isn't perfectly healthy, but as long as I do it rarely it's no big deal, for me at least.
Maybe all Diet beverages are not the same.
Also I did it at lunch where I ate more than usual (LCHF soups), so I was bloated with soups and Coke Zero.
But what about having a Pepsi Max instead of a glass of red wine during the weekends? Which one would impact more my weight loss?
Thanks!
Hi Marcos!
I don't believe anyone have tested this scientifically. But my best guess is that an occasional glass of wine or Pepsi will not significantly impact your weight. :)
You also stated that if the artificial sweeteners weren't the cause of insulin production, then you surmise it must be the caffeine in the soda, but your next experiment will be coffee. According to Dr. Robert Atkins' Diet Revolution, circa 1972, he clearly states that caffeine consumption should be limited to two cups a day due to its ability to stimulate insulin.
I don't believe artificial sweeteners cause weight gain, I believe people cause their own weight gain as it is iIlogical to consume a zero calorie additive that results in a caloric result.
I am not in the medical field. The only proof I have is my own use. I have used artificial sweeteners for over 30 years live a low carb lifestyle. I have not experienced any I'll affects from Splenda (I use Splenda sparingly due to its fillers and that does slow weight loss), sucralose (EZ Sweetz) and Erythirol and neither cause me to overeat.
Good luck with your caffeine experiment.
Why doen't you test them all?
To address the experiment, ketone production is a byproduct of being in ketosis, not the reason for it. Your body will stay in ketosis to keep using ketones for fuel as long as there is no glucose available. Your ketone blood levels mean nothing to being in ketosis or to fat loss. They are not the reason for it, higher ketone blood levels do not mean more fat loss.
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No, otherwise breathing would make you fat (ignoring the obvious reason why breathing technically does).
Now I'm not saying that drinking diet sodas is necessarily healthy but I've lost about 37 pounds so I don't think it has that much of an effect on ketone levels. At least not for everyone.
When I did the Atkins diet some years back there was a special mention in the book concerning coffee intake and how it can upset ketosis. I drank caffeine-free diet Pepsi or caffeine-free diet Coke with no problems