New Research Challenges the Low-Carb Craze

Is the Low-Carb Diet Trend Helpful or Harmful?

Have you or someone you know tried a low-carb diet recently? Although this weight-loss strategy is gaining popularity, you might want to reconsider drastically slashing your carb intake (and what you replace those carbs with!) to improve your health. Interesting new evidence has emerged on the mortality risks of low- and high-carbohydrate diets from the Atherosclerosis Risk in Communities (ARIC) study. If you are looking for a sustainable way to manage your weight and possibly lower your mortality risk, this study suggests incorporating more plant-based proteins and fats into your diet with a moderate (50-55%) intake of carbohydrates may be a good strategy. 

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"Both high and low percentages of carbohydrate diets were associated with increased mortality, with minimal risk observed at 50–55% carbohydrate intake."

Seidelmann, Sara B, et al.

These researchers found that participants on a low-carbohydrate diet had the highest risk of mortality, although participants on a high-carbohydrate diet were also found to have a significantly higher risk of mortality compared to those with a moderate carbohydrate intake. Those with the lowest average carbohydrate intake ate more animal fat and protein and less plant protein and dietary fibre than participants in the moderate and low-carb categories, which may play a role in their increased mortality risk.

Interestingly, researchers found no significant difference in weight gain among participants at 3-year and 6-year time points, regardless of their average carbohydrate intake. This may be disappointing news for the many people following a carb-restricted diet for weight management, as carbohydrate restriction alone does not seem to be an effective weight-loss strategy in the long-term.

Research Methods

This ongoing cohort study has followed over 15,000 adults so far in the United States over 25 years to measure cardiovascular risk factors. Participants were recruited between 1987 and 1989 and examined periodically over time. Any subject missing complete dietary information and those with extreme caloric intake were excluded. All participants were interviewed and completed questionnaires reporting how frequently they ate certain foods and beverages, with standard portion sizes, pictures, and food models provided as a reference for estimation. An extensive list of covariates (such as cigarette smoking status, education level, diabetes status and many more) were adjusted for.

Moderate Carbohydrate Intake Could Lower Mortality Risk

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Carbohydrates, fat, and protein are all essential to good health and extreme intake of any of these macronutrients is not an effective or sustainable method of weight management. More importantly, researchers don't fully understand the long-term effects of swapping out carbohydrates in favour of more animal protein and saturated fat. According to the ARIC study, having too little or too much carbohydrates in your diet could potentially shorten your lifespan, while a plant-centred diet comprised of 50-55% carbohydrates may be beneficial. Here are three safe and healthy dietary changes you can make today to lower your risk:

  • Reduce your intake of lamb, beef, pork and chicken by having more meatless meals that showcase plant proteins like tofu, tempeh, beans and lentils
  • Opt for unsaturated vegetable oils and plant-based fats like avocado and nuts over saturated fats found in animal foods
  • Choose more whole-grain carbohydrates like bulgur, buckwheat, amaranth, kamut, quinoa, rye or spelt


Seidelmann, Sara B, et al. “Dietary Carbohydrate Intake and Mortality: a Prospective Cohort Study and Meta-Analysis.” The Lancet Public Health, 2018, doi:10.1016/s2468-2667(18)30135-x.

Ryan Stallard