Buzz
A recent study published in The Lancet discovered a correlation between high carbohydrate consumption and increased mortality risk. The ensuing media coverage led to celebrations among low-carb enthusiasts and sparked debates among low-fat advocates. However, as with most nutrition studies, the reality is more nuanced than the headlines suggest.
The Headline: Major dietary study indicates carbs, not fats, may pose a greater risk to your health
The Story: The ongoing debate between low-carb and low-fat diets has persisted for decades. News stories often swing between declaring butter harmful, beneficial, or even part of a larger conspiracy, leaving the public confused. In truth, four of last year’s most contradictory studies on butter actually aligned more than they diverged when examined beyond the sensational headlines.
New findings in nutrition science typically reinforce or expand upon existing knowledge rather than completely overturning established principles. This latest study is no exception.
In the study, detailed dietary questionnaires were gathered from more than 135,000 participants across 18 nations. Over several years, researchers tracked these individuals, recording incidents such as heart attacks, strokes, cardiovascular-related deaths, and overall mortality. While everyone’s lifetime risk of death remains 100 percent, the study aimed to determine whether dietary habits influenced the likelihood of death within specific timeframes.
The findings revealed that individuals consuming over 77 percent of their daily calories from carbohydrates faced a 30 percent higher risk of mortality during any given period compared to those who derived less than 50 percent of their calories from carbs. Conversely, those who consumed more than 35 percent of their daily calories from fat had a reduced risk of death compared to those with the lowest fat intake, around 11 percent of daily calories.
Media headlines have suggested that high-fat diets might be protective or that high-carb diets could be harmful, but these conclusions overlook critical nuances.
First, since a low-fat diet is generally defined as one with less than 30 percent of calories from fat, participants adhering to such a diet—typically high in carbs—experienced no heightened risks. The so-called “protective” effect of higher fat intake applied to anyone consuming more than 23 percent of their calories from fat. Even those who ate up to 62 percent of their calories from carbs and as little as 16 percent from fat showed no adverse effects. For context, the CDC’s National Center for Health Statistics reports that the average American derives about 50 percent of daily calories from carbohydrates and 34 percent from total fat.
Additionally, it’s uncertain whether the increased risks observed in this study are relevant to individuals in Western countries. Among the 18 nations studied, several were low- or middle-income countries where diets high in refined carbohydrates (such as white rice) were common due to limited access to diverse, nutrient-rich foods. In such cases, high-carb diets might coincide with malnutrition. Participants in developing nations may also have faced challenges like inadequate healthcare, poor access to clean water and air, or insufficient food to meet their energy or micronutrient needs, all of which could have contributed to their higher mortality risk.
For a deeper dive into the study’s methodology, results, and potential confounding factors, I provided a more comprehensive analysis here.
The Takeaway: Diets extremely low in fat (less than 20 percent of calories from fat) and high in carbohydrates were linked to a higher risk of non-cardiovascular mortality. However, moderate consumption of both fats and carbs showed no such risks. Instead of sensational headlines, it’s wiser to focus on balanced reporting, such as this Science Daily headline: “Moderate consumption of fats, carbohydrates best for health, international study shows.”
