Usually, this type of nonsense doesn’t faze me, but the overwhelming amount of messages I’ve received from people who are doubting if they should eat keto, let alone low-carb, has me more concerned about what this type of misinformation can actually do to people’s health outcomes. I almost got Deja vu thinking back several decades ago to what I refer to as “fat-gate,” or the fat distortion, led by Ancel Keys and several others, did to our society (Check out this hilarious, yet surprisingly accurate video by College Humor on the topic).
So, let’s clear up one of the most common misconceptions floating around right now:
Low-Carbohydrate Diets Are Linked to Increased Mortality
If you haven’t seen the hype around the latest “groundbreaking study,” supposedly indicating that eating a carbohydrate-rich diet will make you live longer, then good for you. You either don’t watch the news (seriously, kudos to you) or you missed just about every media outlet trying to capture the attention of consumers with headlines like, “Low-Carbohydrate Diets Shorten Your Life”, “Low-Carb Diets Can Increase Risk of Early Death”, or the best one I’ve seen yet, by none other than the NY Post, “Eating Pasta Could Save Your Life.”
So, what’s with all this noise, and is the study these articles are referencing actually legitimate? For those of you who want to read the study, you can find it here. However, for those that want a breakdown, I’ll describe 3 key points: the study, the problem, and the actual science.
The “Study” and Its Findings
An observational study was recently published in the highly respected journal The Lancet titled, “Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis.”
- The researchers followed over 15,000 individuals over several years and had them fill out a 66-item semi-quantitative food frequency questionnaire (FFQ) – If you are curious as to what the survey looked like, here is a slightly different version of their questionnaire (https://regepi.bwh.harvard.edu/health/FFQ/files/80out.pdf)
- Participants reported the frequency with which they consumed particular foods and beverages on 2 occasions, six years apart. Their health was then tracked over the next 25 years.
- Researchers pooled the data with other meta-analyses to run further statistics.
- The lowest observed risk was associated with people who reported consuming diets that were composed of 50-55% carbohydrates. (After running statistical models, the authors speculated that, “a 50-year-old participant with intake of less than 30% of energy from carbohydrate would have a projected life expectancy of 29 years, compared with 33 years for a participant who consumed 50–55% of energy from carbohydrate.”)
- Low-carbohydrate dietary patterns that replaced energy from carbohydrate with energy from animal-derived protein or fat were associated with a greater risk of death.
The Problem: Media Data Dredging and Understanding Correlation Does Not Equal Causation
- The “low-carb” groups (<44% carbohydrate) had a significantly higher rate of diabetes (13%) than the other groups.
- The “low-carb” groups also had a higher percentage of current and former smokers.
- The “low-carb” groups had the lowest amount of exercise activity (i.e., they didn’t exercise as much).
- The “low-carb” groups had less total fiber per day than the other groups.
- The “low-carb” group had the highest amount of college graduates. Hey, can we make the correlation that eating a “low-carb” diet makes you more likely to graduate college?! (Just kidding, I had to throw this one in there :P)
- The “low-carb” groups weren’t in any way, shape or form, LOW-CARB: <44% carbohydrate, or about 144-182 grams of carbohydrates per day, based on their reported caloric intake.
- This was a self-reported survey study, taking place over 25 years with follow-ups every few years. I don’t know about you all, but I forget what I had for dinner last night, let alone last year.
- There was NO indication of the QUALITY of the food consumed.
By now, I may sound like a broken record, but correlation DOES NOT equal causation. Just because there is a correlation between two things does not mean there is causal evidence.
The following video provides a great breakdown for those who want more information on correlation vs causation (hint: there is a correlation between ice cream sales and crime rates and last time I checked, eating ice cream doesn’t make you a murderer – at least I hope not).
The Actual Science:
- “The objective of this study was to mimic this metabolic shift using low-carbohydrate diets and to determine the influence of these diets on longevity and healthspan in mice. The ketogenic diet (KD) significantly increased median lifespan and survival, compared to controls. In aged mice, only those consuming a KD displayed preservation of physiological function, memory, and muscle mass.”
- “We show that a non-obesogenic ketogenic diet improves survival, memory, and healthspan in aging mice.”
- “BHB also signals via extracellular receptors and acts as an endogenous inhibitor of histone deacetylases (HDACs). . . HDAC inhibition by the ketone body βOHB may modulate metabolism and diseases of aging.”
- “Aging constitutes the central risk factor for major diseases, including many forms of cancer, neurodegeneration, and cardiovascular diseases. The most robust intervention extending lifespan, plausibly impinging on the aging process, involves different modalities of dietary restriction (DR). Ketogenic diets, including DR, may entail similarly protective epigenetic mechanisms.”
- “Ketone bodies have signaling functions, as well as being a mobile source of cellular energy. Ketone bodies inhibit histone deacetylases and control gene transcription. Histone deacetylase function is implicated in the regulation of aging. Ketone bodies may link environmental cues, such as diet, to the regulation of aging.”
- “The prospective cohort study, named PURE, found that in >135,000 participants from 18 countries, nutritive carbohydrates increase human mortality, whereas dietary fat reduces it. Experimental evidence from animal models provides synergizing mechanistic concepts, as well as pharmacological options, to mimic low-carb or ketogenic diets.”
- “In postmenopausal women with relatively low total fat intake, a greater saturated fat intake is associated with less progression of coronary atherosclerosis, whereas carbohydrate intake is associated with a greater progression.”
To spare you hours upon hours of reading, I won’t continue to cite the plethora of other studies out there that have found results to counter those described in the study published in the Lancet. We could sit here all day and look at correlative data and make it out to be the next big headline. Where are the media outlets jumping all over this study from 2005 that found that “a high intake of carbohydrate, glycemic load, and glycemic index increases the risk of symptomatic gallstone disease in men”? These results add to the concern that low-fat, high-carbohydrate diets may not be an optimal dietary recommendation.
A similar headline might be:
“Want Gallstones? Eat Pizza, Not Cauliflower Crust, with Breadsticks on the Side”
This article is meant to bring awareness to the fact that not everything we see or hear on the news, or on the latest “ground-breaking” article is legitimate. I hope that by reading this, either you, a friend, a colleague, might not only change their outlook on the recent headlines surrounding the ketogenic diet, but information consumption as a whole. It’s difficult to weed out the noise in today’s social media-driven society, but at the same time, I encourage you to do your best to find legitimate, trusted sources that you anchor to for quality information. Continue to ask questions. Continue to explore. Continue to be your own scientist and find out what works best for your body. Until next time, I’ll be sitting here, still pondering how pasta might be able to be used in other ways than food consumption, in order for it to truly be able to “save our lives.” This is all I could come up with, but if you have any other ideas I’d love to hear them
Love y’all and continue to #makepositivitylouder
- 1. Roberts, M. N., Wallace, M. A., Tomilov, A. A., Zhou, Z., Marcotte, G. R., Tran, D., … & Imai, D. M. (2017). A ketogenic diet extends longevity and healthspan in adult mice. Cell metabolism, 26(3), 539-546.
- 2. Newman, J. C., Covarrubias, A. J., Zhao, M., Yu, X., Gut, P., Ng, C. P., … & Verdin, E. (2017). Ketogenic diet reduces midlife mortality and improves memory in aging mice. Cell metabolism, 26(3), 547-557.
- 3. Newman, J. C., & Verdin, E. (2014). Ketone bodies as signaling metabolites. Trends in Endocrinology & Metabolism, 25(1), 42-52.
- 4. Moreno, C. L., & Mobbs, C. V. (2017). Epigenetic mechanisms underlying lifespan and age-related effects of dietary restriction and the ketogenic diet. Molecular and cellular endocrinology, 455, 33-40.
- 5. Ravichandran, M., Grandl, G., & Ristow, M. (2017). Dietary Carbohydrates Impair Healthspan and Promote Mortality. Cell metabolism, 26(4), 585-587.
- 6. Mozaffarian, D., Rimm, E. B., & Herrington, D. M. (2004). Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. The American journal of clinical nutrition, 80(5), 1175-1184.
- 7. Tsai, C. J., Leitzmann, M. F., Willett, W. C., & Giovannucci, E. L. (2005). Dietary carbohydrates and glycaemic load and the incidence of symptomatic gall stone disease in men. Gut, 54(6), 823-828.