This study is highly flawed:
https://www.hsph.harvard.edu/nutritionsource/2017/09/08/pure...
Be careful making any changes to your diet based on these "findings". The healthiest populations on the planet eat plenty of carbs, but not refined sugars.
I'm not surprised to see this at the top of HN considering how many people seem to be fans of the Keto Diet. I am very excited for people who find something that works for them, but I would be very wary of a study like this if you are looking for confirmation for multiple reasons:
1. The study "did not analyze which specific source of carbohydrates (e.g., sugar/refined carbs versus whole-grain products) may contribute to the detrimental effects of carbs observed, especially since income and wealth do impact the quality of dietary choices significantly."
This is HUGE. Any study or person that attempts to label an entire macronutrient as "bad" or "evil" is not helping anyone understand the whole picture. The most nutritious foods in the world are carbs. Many of the least nutritious foods are also carbs. Not distinguishing the two gets us nowhere.
2. With this study and most high fat/keto diet studies as well, the timeline is not long enough to tell us about true "lifespan" impact. This one is over 7.4 years. I know it's more difficult to do 10, 20, 30 year studies, but until something can be correlated over those timespans, I would not bet everything on that diet for longevity. There are a handful of generational studies, and almost all have shown that "high carb" or more specifically "plant based" ARE good for longevity. Not saying high fat aren't good for longevity as well, but we have yet to really see examples yet.
3. As many who have tried Keto specifically will tell you (as some have mentioned in the comments), it is very difficult to maintain a ketogenic state. You have to be very disciplined, and this is made harder when you are a social person. This is a big problem when talking about diet and longevity. If it's not fairly easy to maintain, then it's not a feasible diet for longevity where the average person is concerned.
4. As someone else mentioned, the percentage of carbs that the studies participants were eating were not even close to the level required for a Keto Diet
I've read a lot of, often conflicting, dietry guidance. I have realised one very important thing: humans will very easily accept that something they enjoy is bad for them (see fat, sex etc.) So listening to what people say is bad for them is stupid.
Instead I have taken a simpler approach: I observe the lifestyles of people who are healthy and live a long time. I have observed that eating simply "good, old-fashioned" home cooked food is important. My grandmother lived into her 90s. Ate fat and carbs. Julia Child lived into her 90s. Ate fat and carbs. Edna Lewis lived into her 90s. Ate fat and carbs. I could go on. Just do what they did and you'll have as good a chance as any.
I’ve been living a ketogenic lifestyle for a few years now. I go in and out once and a while but seeing the “fat is bad” theory thrown out the window with research like this makes it easier to remain committed.
The trouble comes with the way society has been conditioned to have carbs with every meal. Like 90% of the food my peer group eats are surrounded in carbs. Even for a company-wide lunch in the office: the go-to is usually a couple dozen pizzas.
Once you’ve lived low carb for a long time you look at people in line at a coffee house grabbing a bagel and a milkshake and just feel bad for the crash they will have later.
I’m happy to see Keto becoming more and more socially known. Accessiblity around low carb options is getting better and better. My favorite will always be a protein style burger from In-N-Out though.
> Next, a number of studies have evaluated the effects of specific macronutrients on lifespan, initially in S. cerevisiae (Lin et al., 2002), subsequently in C. elegans (Schulz et al., 2007 and follow-ups), and mice. Out of the latter, two studies in the previous issue of Cell Metabolism have studied this in mice starting at 12 months of age. In regards to the PURE study, most notably, the almost complete removal of carbohydrates (<1%) from the diet to generate a ketogenic diet extended lifespan compared to a high-carb diet. However, reconstituting only 10% of energy of the ketogenic diet by sugar abolished this effect (Roberts et al., 2017), suggesting that specifically sugar (rather than carbohydrates in general) has the most relevant effect on lifespan. Along this line, it is also interesting to note that when nutritive sugar content is kept constant, a different (and less extreme) high-carb diet exerts the best effects on murine lifespan. By contrast, a high-fat diet still containing the same amount of sugar, but no other carbs reduced lifespan slightly. Lastly, when combining high-fat and high-carb components from the two previous diets, the worst effect on lifespan was observed (Keipert et al., 2011). Moreover, lifespan extension in mice was also obtained when dietary protein was replaced by carbs, possibly independent of the total uptake in calories (Solon-Biet et al., 2014). Taken together, these studies suggest that dietary sugar may be one important, but not the only, nutritional factor in limiting healthspan in rodents, hence additional studies are definitely required to establish firm evidence in model organisms.
This section of the article does not correspond to the title. In fact it seemed all over the place, then goes on to conclude ‘maybe it’s refined sugars.’
Related; I saw on Hacker News awhile back a really great website that aggregates a lot of this health research and then gives summaries of, "What's the current known truth" based on all of the varying research. They then re-market that data as a service somehow. Anyone on here recall this by chance as I'm no longer able to locate it?
Does it bother anyone that this study is intentionally misleading by masking the fact that the carbohydrates tested were refined sugars?
I’ve found eating out socially on keto a big challenge (carbs still look delicious) until I found a hack: unreasonably large portions of salad, covered in salt. Salt is fucking delicious. Add olive oil too if you feel like it.
And yet many of the longest-lived populations on earth have diets rich in carbohydrates, like the Okinawans.
I hate associational studies like this which don't distinguish between types of carbohydrates (sugar vs starch) or other factors, like whether they were eating whole meals of natural foods or snacking on potato chips 24/7.
But at least they've finally noticed they were completely wrong about saturated fat for 80 years.
tl;dr Refined sugar contributes to getting fat, and an early grave. No shit, Sherlock. They conveniently left out any reference to fiber, or the exact sources of said carbohydrates. Sources matter tremendously due to fiber content and levels of refinement.
Stick to fibrous veggies, beans, nuts, some fruit (berries are best), and you'll be just fine eating carbs.
I'm not contesting the fact that ketogenic diets work for people. But this study is kinda bullshit since it's basically alluding to the worst kind of high GI refined carbs
>>> (1)The conversion of D-glucose into metabolic intermediates, namely glycolysis, can be inhibited by compounds like (the highly efficient but rather toxic) 2-deoxy-D-glucose or (the less efficient but completely harmless) D-glucosamine (GlcN). The latter is widely used to treat arthrosis with the questionable claim of inducing cartilage regeneration. Both compounds have been shown to extend C. elegans lifespan (Schulz et al., 2007, Weimer et al., 2014), while only GlcN extends lifespan in rodents (Weimer et al., 2014). Notably, GlcN uptake has been also associated with reduced mortality in a large human cohort (Bell et al., 2012).
So does this mean the glucosamine chondroitin pills I take for my joints will help reduce glucose conversion and extend my lifespan?
As usual, correlation is incorrectly assumed to mean causality.
The summary text says there's causality. A few paragraphs into the study, the text interchangeably uses causality and correlation:
>> found that carbohydrate intake was associated with increased total mortality.
>> By contrast, any type of dietary fat reduced the likelihood of dying.
Can anyone provide a TLDR on what exactly the conclusion of this article is? My experience with a low-carb diet is quite similar to that of @whalesalad, and it remains much more effective than any other diet or a strict exercise regimen.
Take home message?
Eliminate sugar, increase saturated fat. This study provides little guidance on question “is total keto good or not”.
"Moreover, there was no link to cardiovascular events or related mortality, except for saturated fats, which were unexpectedly associated with a lower risk of stroke."
That's interesting.
Man I'm screwed. Don't drink, don't smoke, but totally addicted to carbs. Granola bars...mmmmmm
Note that this is probably not what you are thinking (low-carb, very-low carb or even keto diets are good for your healthspan).
The lowest quintile in this study were consuming 46,4% of kcal from carbs (that's about 230 gram of carbs for a 2000 kcal total intake). Not even close to low carb by today's standard in the health blogosphere.
The authors make this explicit in the discussion section:
>>> However, the absence of association between low carbohydrate intake (eg, <50% of energy) and health outcomes does not provide support for very low carbohydrate diets. Importantly, a certain amount of carbohydrate is necessary to meet short-term energy demands during physical activity and so moderate intakes (eg, 50–55% of energy) are likely to be more appropriate than either very high or very low carbohydrate intakes.