Perhaps the next big eating trend is the not-too-sexy-sounding medium-carb diet.
A study from Brigham and Women’s Hospital, Boston, which involved more than 15,000 Americans tracked for a quarter of a century, found a U-shaped link between carb intake and life expectancy. During the study period, those who ate a low-carb diet (less than 40% of daily calories) or a high-carb diet (more than 70% of daily calories) were more likely to have a lower life expectancy than those who ate a moderate-carb diet, where 50%–55% of calories hailed from carbs. Published in the August 2018 edition of The Lancet, the study also linked low-carb diets that replaced carbs with animal-based proteins and fats to a greater risk of early death than low-carb diets that subbed in plant-based proteins and fats, like those found legumes and nuts.
People eating lofty amounts of carbs might be consuming too many refined grains and sweeteners, whereas animal-based, low-carbohydrate diets like Paleo® and keto might set some people up for a shortfall in certain important nutrients and antioxidants. A moderate carb intake can be an indication that someone is eating a well-balanced diet.
Yes, this study found only an association between moderate carb intake and longevity based on self-reported diet intake. It did not prove that low- or high-carb diets cause an increase in early death rates. Nevertheless, we may be getting closer to finding that elusive sweet spot for carbohydrate intake.