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?
Maybe it's not the caffeine?
Maybe it's not the artificial sweetener?
but possibly the carbonation?
Does carbonation affect ketones?
a) The artificial sweetener caused the response
b) The caffeine caused the response
c) The ultra-palatability of the food caused the response
d) There was a placebo response because he expected (or wanted) something to happen
e) The anticipation (and expectation) of receiving food caused the response (so it was nothing unique to just the soda but any food source)
f) One of the other hundred chemicals in the soda caused the response.
g) One or more of the above interacted together to elicit a response that would not otherwise happen if each individual component was tested individually
With the exception of d and e, you could still make the conclusion that drinking a Pepsi Max would elicit some form of response but it's impossible to pinpoint the causal factor. However, it's also impossible to know if the response wasn't caused by d and/or e so it's impossible to interpret the results and find the causal agent and you definitely can't conclusively say the response was caused by the Pepsi Max (let alone blaming some singular component of the Pepsi Max for the response).
Nice self-experiment though, I'll probably repeat something similar on myself soon but I'll test only once but I'll repeat the test once every three days for ten total tests to see if the response is the same every time. That way i can hopefully eliminate any non-physiological responses.
As a better future experiment, you might want to consider just mixing artificial sweetener with water, and then combining pure caffeine with water, and then have a control (pure water) and then possible even have a mildly salted water to hopefully rule out any response due to the taste.