The Slow Carb Rule I Don’t Agree With

It’s a simple lifestyle – beans, protein and vegies, and then that fun day of the week where anything goes. So what’s not to like? Great health results, losing fat, building muscle – it all seems pretty great. But there’s one particular recommendation Tim Ferriss made that I’ve never agreed with, and research now proves it could see your waist line expanding over the next 5 or 10 years. Find out what the problem is, right now, and stay lean for life.

Beyond the five simple rules of slow carb, there’s a lot of ‘oh but’s’ included for those who are enthusiastic to follow slow carb to the letter, with desires of losing fat and changing how the body looks and feels. It’s one of those little rules that’s got me worried. And some research I came across recently has made it even more important to share this with you.

Though mentioned in the book as an acceptable alternative, I strongly advise against drinking ‘diet’ soda, ‘diet’ pop, or ‘diet’ soft drinks (depending on where you live), and any other ‘diet’ drinks (including artificially sweetened protein drinks, and chocolate drinks). For some people, this might not change a thing, but for others, this could substantially change how you think about your weekly routine.

Before I hear protests about diet drinks not containing any calories, and them not having any sugar, let me say clearly, that this recommendation is not based solely on the suspected link to blood sugar and insulin that has been mentioned online, and may apply to certain artificial sweeteners – this advice is based on a scientific study done by the University of Texas last year.

The findings of the researchers was that quite clearly, there was a correlation between those people who drank diet drinks, and the size of their waist line.

The researchers actually tracked nearly 500 people over almost 10 years of their lives, to see if there would be any long-term effects from these drinks.

Their conclusion?

They saw a sharp increase is waist lines for those people who drank diet drinks. Especially for those who drank 2 cans, or more, per day – their waists were 5x more likely to increase than non-diet drinkers.

Another research project saw that mice, when fed aspartame in their diet, had higher blood sugar after 3 months, compared with mice who ate regular food. This is another great warning sign that these chemical sweeteners are not for anyone who has health and longevity on their mind.

The third strike comes from the co-author of the studies, who says that artificial sweeteners could stop the message getting to your brain that you’re full. Obviously this has huge consequences for anyone eating using any method other than counting calories. In this scenario, the worst thing to do would be listen to your hunger. And let me make it clear that I don’t believe we should have to count calories to stay at a healthy weight.

So how is it happening?

Pretty simply, according to the researchers, it’s likely that the artificial sweeteners are triggering hunger when they’re eaten, but then basically don’t deliver on that promise of ‘food’ when they arrive in the stomach. This confuses the body, and the result, on a biochemical and hormonal level, is still unknown. What has been demonstrated, however, is the external effect – waist lines increasing.

Even when researchers isolated out other lifestyle factors, like exercise, the results still showed the link between ‘diet’ drinks and waist size increasing.

Currently, there’s no research like this that has been done on natural sweeteners that are calorie free – specifically, Stevia. Stevia is a plant extract that is 100 times sweeter than sugar, and therefore is only used in very small amounts. It has no calories. It is difficult to say whether or not Stevia would have the same effect on hunger, or whether the current research that shows it does not affect blood sugar is a reliable indicator that it works differently than artificial sweeteners. Only time will tell.

Personally, I feel it’s wise to avoid the artificial sweeteners entirely, and that means keeping an eye on not just soda or pop. To be fair, Tim Ferriss has recommended against protein drinks with artificial sweeteners, citing blood sugar bumps, however I feel diet drinks need to be targeted, and removed from the ‘OK’ list entirely. Avoiding artificial sweeteners also means checking other products beyond drinks these days, that you might think are healthier than their ordinary counterparts – like low sugar yogurt, especially (though of course this might only be an issue if you are on slow carb and eat yogurt on cheat days).

Though this might come as a disappointment, or a shock for you, if you drink diet drinks right now, the good news is that ending that habit is likely to bring better results for you. Of course, there’s no guarantees as to how long that will take, but I expect in a few years’ time the body will have adjusted, without artificial sweeteners, to a healthier and more natural, balanced state.

Please pass this along to friends and colleagues who may be diet soda drinkers – with the diet fads sweeping through the media and grocery stores, and more people switching to what they think is a healthier alternative (and medical professionals even recommending diet drinks), I think this information is very important and needs to reach as many people as possible.

If you’ve got a sugar craving you’re having trouble kicking, you might want to read about Turbo Tapping – click here for more info.

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28 Responses to The Slow Carb Rule I Don’t Agree With

  • Tanja says:

    This information is not new… A lot of people have this opinion. Even artificial sweeteners seem to have the effect of increasing your insuline. I tought Tim Ferris did not say you can have unlimited access to diet soda and that he mentioned drinking 1/2 liter and that merely because he can not stop drinking his diet coke… :p

    • Luke says:

      Hi Tanja, thanks for your comment. You’re right that these sentiments have been expressed in various forums over the last few years. Having not discussed it specifically on our blog, I felt it worthwhile to bring this information to my readers.
      He didn’t say unlimited access, however my thought is that any diet soda is too much. If you need a caffeine hit, then coffee is a much healthier alternative.

  • Jason says:

    Luke, I completely agree with you, but I think (without having read it, admittedly) there’s a huge hole in the study.

    People with bulging waistlines don’t drink diet soda because we are trying to lose weight. Necessarily. We’ll still get a big mac with a supersized fries and a diet coke. The diet coke makes us feel better about our terrible health situation. I can say that because I’ve lived it. :)

    My immediate reaction was that their waistlines were getting larger not because of the diet soda but rather because they were failing to change the rest of their food habits. I don’t think it’s impossible that this study is proving something; I just question the accuracy of their extrapolation.

    Most of the people I know, when really trying to lose weight and get healthy, cut out sodas completely – diet or otherwise. I personally rarely drink it anymore, but mostly for the chemicals. I’ve also found in my experience that drinking diet soda only made me feel more hunger or crave other sweets. Sticking to water mitigates that.

    Anyway, I appreciate what the study is trying to prove, and I appreciate that you’re talking about it!


    • Luke says:

      Hey Jason, thanks for your thoughts! I updated your comment based on your edit – so it reads as you intended.
      I recognize that this type of correlation is open to interpretation, and I think your suggestion is a valid one. It’s hard to say if that would apply across all those people whose waistlines were increasing, or only some, ie 50% due to diet drinks, 50% drinking diet drinks to feel better about eating fast food. It’s hard to say. Or it could be 100/0 or somewhere in between.
      I also find drinking diet soda spikes my hunger, which can at times be uncontrollable, and different to any other kind of regular hunger, so I steer clear these days.
      I guess time will tell, as more studies are done. For now, I think diet drinks are best left with all the other artificial, man-made fake-food, which will all hopefully be just a memory in history soon.


  • Joules Jones says:


    Another flaw of the study is that people who drink diet soda are already overweight with large waist lines and that is why they are trying to cut out the extra calories. The study does not control the other areas of the diet that the people were on.

    If they had 2 subgroups who ate the exact same , who exercised the same except for diet vs regular soda….and they were quarantined to be sure they did not cheat….then had different waist lines….then I would believe the study. However, there are just too many other variables to ever get a study to be accurate.


    • Luke says:

      Hi Joules, thanks for your comment.

      You may be interested to note that ” 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.” -

      So in this case, it would seem that for anyone who had a large waist line to begin with, this was taken into account in the study, though I think perhaps you are talking more behaviorally – that non-overweight people won’t choose diet drinks. In fact, this is not the case, as diet drinks are promoted as healthier alternatives to the whole population, not just overweight people, and with the rise in awareness of diabetes and obesity, more people who are not overweight are selecting diet drinks, instead of high fructose corn syrup based sodas. In fact, for someone wanting a soda in North America, it is a diabolical choice between high fructose corn syrup, which has been shown to cause a myriad of health problems, including an increase in weight (due to it being a very effective obesogen), and the alternative – diet drinks with equally harming artificial substances. Effectively, a catch-22, when so much pop media promotes soda as a popular drink – thus reinforcing a self-feedback loop of people believing it is OK to drink soda, because everyone else is.

      All the best,

  • Jay says:

    Is stevia okay since it’s not artificial but natural?

    • Luke says:

      Hey Jay, this is an important question I mention here. There’s no conclusive evidence either way, and for now, I’m not prepared to trust some kind of ‘gut instinct’ of mine, that’s not founded in facts and evidence, and make any recommendations. If you’re interested, there is quite a bit of information available on Stevia, online, so you may want to do some further reading.
      All the best,

  • PhilT says:

    Got a link to the studie splease ?

  • Dave says:

    I read your blog because you help me fine tune the results I am seeking. My weight is dropping slowly and I am trying to accelerate my results. I haven’t been drinking diet soda, but appreciate your recommendations since I don’t hear many clarifications directly from Tim. I suspect that you have many readers similar to me. Keep up the great work and thank you for sharing your advice!

    • Luke says:

      Hey Dave, thanks so much for your comment. I really appreciate the feedback. I do my best! I think there’s a lot of clarification needed, for people who are practically making this a part of their lives, but without having all the science background that Tim had (and therefore was able to make easy case-by-case decisions on different foods and drinks).

  • Cindy Hick says:

    Hi Luke,

    I cut out all artificial sweeteners in January of this year, in February I cut out soda completely, by the end of February I also was able to cut out my high blood pressure medication. It was the only change I made to my diet. My doctor was amazed.

    • Luke says:

      Wow Cindy that’s really incredible. And disturbing at the same time!!
      The more artificial things in our body, the more strange results we’ll have. Getting back to basics – whole food and some exercise, really can work wonders, though the pharmaceutical companies would probably prefer to keep everyone on medication!

      All the best in great health,

  • Nolan Foss says:

    Tim did not say we could drink diet soda per say; he said that 16oz a day did not affect weight loss (for those diet coke/zero addicts) I think that if you try to follow the “whole food” approach for the 4HB lifestyle you will naturally let go of artificial sweeteners and thus the diet soda

    • Luke says:

      That’s correct Nolan – but he has made comments mentioning that diet anything have been some folks’ hurdle to fat loss, or cause for plateaus in fat loss. Ideally, artificial anything is best avoided, because we just don’t know what it’s doing inside our bodies. There isn’t really a non whole food approach to slow carb – it’s legumes, meat and green veges, effectively. Those using protein powder or other alternatives are actually not following the slow carb principles, though some people do have success making modifications and still getting fat loss.
      All the best,

  • doug sheehan says:

    OK, here is my issue with the study and the discussion. The study doesn’t look at diet drinkers vs. regular drinkers. If it did, I would bet the regular drinkers would have substantially larger waistlines. I believe diet drinks don’t fill you up and the chemicals may be bad for you, but they don’t dirrectly make you gain weight,

    I was a diet drinker for years(1-2 cans per day), and I started this diet with 30% body fat. i loved my carbs, and ate them with every meal. Still drink an occasional diet drink, and I’m down 20 lbs. in 8 weeks. Actually, I haven’t craved the drink the past few weeks. Water is more satisfying.

    Just my opinion.

    • Luke says:

      Hey Doug,
      Thanks for sharing your thoughts.
      It’s difficult to say, with regards to diet drinks, if there is absolute proof currently. That said, I believe the artificial sweeteners can diminish one’s ability to judge calories over time, and therefore, unless someone tracks everything they eat all the time, more likely this will lead to food overconsumption, and weight gain. Cheers,

  • Shmully says:

    The thinking is that artificial sweeteners trick Your body into thinking it needs to release insulin to Take up sugar. Now there is Insulin release but no Sugar so your body triggers a hunger response to get sugar to get rid of the insulin. However, this would happen after the artificial sweetener was absorbed into the blood stream. Thus, FYI, splenda (sucralose) doesn’t cause hunger, as other artificial sweeteners would, because it is not absorbed and is all excreted. Also, unlike other artificial sweeteners, Sucralose has been thoroughly tested and its safety is without controversy. As a nutrition expert, I do Agree that staying away from sodas and any sweeteners is best practice. Stevia, Btw, is a super heated and bleached processed Extract of a Small Fraction of the whole leaf. That’s why the Leaf is green while the product is white. It is also Frequently cut with agave, but that is only revealed to consumers who read the ingredients,

    • Luke says:

      Hey Shmully,
      Thanks for your comment.
      Sounds like you’re quite interested in the topic, so I really appreciate you weighing in with your thoughts. Though Sucralose may not be fully absorbed, there’s a lot more to the story than that. On average 15% of sucralose is not excreted, meaning it stays in the body, and the chemical composition is why most people can’t break it down – it’s a molecule that doesn’t occur in nature. It has chlorine added in the process, and though the manufacturers will say there’s over 100 studies done on Splenda, less than 10 have been on humans, and no study has run longer than 3 months. Considering it is such an artificial, man-made item (not food), my thought is that it’s likely there’s a potential for negative impacts we might not even be able to measure currently. At the end of the day, it’s an individual choice, but nature gave us plenty of ingredients to use as food, I don’t see why we need to be creating any new ones.
      Stevia too is highly processed, compared to the original leaf, less processed alternatives to the white powder version are available.


      • shmully says:

        Hey Luke,

        Not in any negativistic, argumentative spirit that so often happens on the internet, as I am all about collaborative learning and positive spirit. Did want to reply to your reply. Foremost, I am in total agreement with your thoughts that there is no need for anything unnatural. I don’t eat sugar of any denatured kind (meaning only non-extracted sugars occuring in the whole foods I consume). The stats I’ve sen on Sucralose have the upper limit of what is absorbed and not excreted as 8.1%, not 15%. The average would be more around 4.5%. The fact that a chlorine molecule is added isn’t necessarily bad. For instance, table salt is sodium with a chlorine molecule added, and it is not harmful unless eaten in excess, and that is due to the sodium rather than the chlorine. finally, the fact that most studies are on animals is not any more of an issue than it is with all of the many scientifically studied remedies for illnesses that have been tested mostly on anaimals. I wish we didn’t use animals for studies, but almost all substances that need fda approval have been studied mostly on anaimals, as they would have to be before the fda would approve them to be studied on humans. and once human studies are approved the fda requirements are less stringent for amount of studies before the substance may go to market than it is about the amount of animal studies and the quality of results required to go to human trials. so, to my way of thinking, if i work with someone who really won’t change their habbits enough so as to consume little to no sweetener, by far of all the sweeteners available sucralose stacks up better than any other, that is for someone who really wants the taste and versatilty of real sugar (which stevia, date sugar, etc. don’t offer). Anyway, again just in th spirit of dialogue, not arguimg. Of course your info on sucralose may be more accurate than mine. with info so ubiquitous nowadays thatt can be hard to figure out. Anyway, cheers. – Shmully.

        • Luke says:

          Hey Shmully, really appreciate your reply. The points you make are good ones, and I too am always interested in good debate in the spirit of discussion and revealing the facts. Thanks for sharing the stats you did – as you say it depends on sources as to what you find these days. Regardless, I do see your point in terms of ‘harm mitigation’ – that if someone literally won’t give up sweetened products, that sucralose may be better than sugar, as at least it won’t lead to diabetes and all the issues that come with that problem. It does concern me though that someone who may have a weight problem, and have the common depression, low energy problems that may come along with this may then also be subjecting themselves to “gastrointestinal problems (bloating, gas, diarrhea, nausea), skin irritations (rash, hives, redness, itching, swelling), wheezing, cough, runny nose, chest pains, palpitations, anxiety, anger, moods swings, depression, and itchy eyes.” (Brahmini, 2012) rather than finding out that living can feel a lot better when one’s body is not dealing with chemicals and excess weight. Both of which can be alleviated by consuming whole foods and meals made with whole foods.

          Interested in what you think! Is it possible to help someone find a path to experiencing the great feeling of a healthier body, or is it sometimes just too difficult, and it’s about helping a person avoid illnesses they may be headed for?


          • shmully says:

            Hey Luke, It’s a great question. In addition to Being a Certified Sports Nutrition Consultant, Nutrition as Medicine Expert, and Certified Fitness Trainer, I have been a Licensed Psychotherapist since 2003. So, on a daily basis your question is at the core of what I work on, think about and study. My background in addiction treatment and the workings of the brain and nervous system would tell me that it will be extremely hard for many people to make the most crucially healthy dietary changes as long as even the supposedly healthy food stores, such as whole foods, are predominantly sugar dealerships. we all have heard of the old studies done on rats that showed when cocaine was placed in their cages the rats went only for the cocaine and ignored their food and water for days. sugar is a different substance from cocaine, yet it has been shown to have the same neural networking effects as any drug has, permanently rewiring the brain to become addicted to it. unfortunately, what was not told to us about those rat studies is that they actually let the rats go into a large filed that had cocaine placed throughout it and easy to find. In that natural setting for rats, however, no rat, not one, sought out any of the cocaine, even though just moments earlier they had been in a confined environment that coerced them into addiction. I see our food supply in that light. ending one’s sugar consumption is not easily done when the majority of what is called food in our stores and eateries is so laced with sugar, its consumption is normalized to a degree that few would be willing to consider their sugar consumption as identical, in bio-psycho-social terms, to alcoholism and any other addiction, and we are given so much misinformation by supposed super-health gurus that certain sugars (Agave, Coconut Sugar, etc.) are actually healthful. on the other hand, i have found that there are incredible change stories that can and do happen when a relationship is forged between someone who is considering change and a compassionate helping professional who comes to the relationship truly believing in the person’s ability to change and enacting a true collaborative spirit through which yearnings, hopes, strengths, past successes, and innate resiliency are championed towards the change. there are no guarantees, though, but i always carry a ton of hope. a quick note going back to Splenda: Brahmini didn’t do the studies but wrote a summary abstract of myths and facts about splenda, which sites the duke university study but qualifies it quite a bit and comes down on the side essentially that splenda is probably safe with some reservations. and, the duke university study itself was heavily panned by all of the major independent university research bodies in the U.S. This was for two reasons: Foremost, it had several major methodological flaws. The second major reason was that it was, in fact, funded by the natural sugar industry and then used in a law suit by said industry in an attempt to sue the makers of splenda to force them to stop advertising it as a sugar substitute. the judge, however, did not allow the study to be used in the law suit, and the sugar industry lost. To all things healthy and wise, Shmully.

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