Will A Low Carb Diet Really Knock Years Off My Life?

low carb

Recently, there was a study published in The Lancet claiming that a low carb diet could shorten a person’s lifespan. As a result, mainstream media jumped to their own conclusion and came up with their usual alarmist headlines warning people about the danger of a low carb diet, including the keto diet. But is there any truth behind this?

Chris Kresser, a functional and integrative medicine practitioner and proponent of the Paleo dietsays this about the media misinterpretation:

Unfortunately, this study has already been widely misinterpreted by the mainstream media, and that will continue because:

  1. Most media outlets don’t have science journalists on staff anymore
  2. Even so-called “science journalists” today seem to lack basic scientific literacy

Will A Low Carb Diet Shorten My Life?

What Is The Lancet Public Health Study All About? 

In the study published by The Lancet Public Health, 15,400 people from the United States were asked to fill out some questionnaires regarding the food and drink they consume, including the portion sizes. From this, researchers estimated the proportion of calories they obtained from eating proteins, fats, and carbohydrates.

After observing the group for an average of 25 years, they found that people who obtain 50 to 55 percent of their energy from carbohydrates have a slightly lower risk of death unlike those in the high and low carb groups. This has made them to conclude that eating a very low and very high carbohydrate diet can shorten a person’s lifespan.

Here’s the interpretation of the study:

Both high and low percentages of carbohydrate diets were associated with increased mortality, with minimal risk observed at 50–55% carbohydrate intake. Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain breads, were associated with lower mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and mortality.

Why Eating Low Carb Will Not Shorten Your Life

There are various limitations to the study, which is why it’s truly unfortunate that a lot of media outlets have jumped to their own sensationalist conclusions without doing their own proper research. Here are some of these limitations:

No focus on nutrients – the researchers of the study have speculated that the Western type of low carb diet does not include intake of fruits, vegetables, and grains. They assumed that these diets consist mainly of animal proteins and fats that are often link to inflammation and aging. But this is not really the case because low carb diets like the keto diet encourage the consumption of healthy fats. It is clear that the participants who were on a low carb diet were not following the Ketogenic type of diet that’s high in healthy fats and nutrient-rich foods. The researchers have, in fact, pointed this out:

“By contrast, the animal-based low carbohydrate dietary score was associated with lower average intake of both fruit and vegetables (appendix pp 9, 10).”

According to an article in the New Scientist online Sara Seidelmann, at Brigham and Women’s Hospital in Boston, said

The more you exchange plant-based fats and proteins for carbohydrates, the more the risk lowers.

Certain factors are not adequately controlled for – one of the problems with observational studies is that the people involved don’t live in a highly-controlled environment and there are variables that could affect the health and lifespan of humans, such as air and water quality, genetics, lifestyle, etc. This is one of the reasons why nutritional studies are heavily criticized. In fact, an article from the Mayo Clinic Proceedings claimed that:

nutrition studies cannot be reliably, accurately, and independently observed, quantified, and confirmed or refuted,” they do not follow the scientific method and should be regarded as “pseudoscience” at best.


It should be clear by now why eating a low carb diet does not necessarily mean it will shorten your life expectancy. The Lancet study is not based on solid pieces of evidence. By having a clear grasp of the problems associated with these types of nutrition studies, you should be able to protect yourself from these sensationalized headlines that are merely based on poorly designed studies. If you’re following a low-carb diet and the ketogenic lifestyle, continue with what you are doing. You are definitely on the right track to a healthier and longer life.


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