Low-carbohydrate and low-fat diets have gained popularity for weight loss and blood glucose control, but their long-term impact on life expectancy remains uncertain. A study conducted by researchers at Nagoya University Graduate School of Medicine in Japan examined the association between carbohydrate and fat intake and the risk of mortality among 81,333 Japanese individuals over a period of 9 years.
The study assessed daily dietary intakes of carbohydrates, fats, and total energy using a food frequency questionnaire. Carbohydrate and fat intakes were calculated as a percentage of total energy intake. The quality of carbohydrate and fat intake, such as refined compared to minimally processed carbohydrates and saturated compared to unsaturated fats, was also considered.
The findings revealed that men who consumed less than 40% of their total energy from carbohydrates had significantly higher risks of all-cause and cancer-related mortality, regardless of the type of carbohydrate consumed. In contrast, women with a high carbohydrate intake of over 65% had a higher risk of all-cause mortality, although no clear association was found between carbohydrate quality and mortality risk in women.
Regarding fats, men with a high fat intake of over 35% of their total energy had a higher risk of cancer-related mortality. Low unsaturated fat intake in men was also associated with a higher risk of all-cause and cancer-related mortality. In contrast, women who consumed higher levels of total fat intake and saturated fat showed an inverse association with the risk of all-cause and cancer-related mortality.
The study’s lead researcher, Dr. Takashi Tamura, highlighted that the findings indicated saturated fat intake was inversely associated with mortality in women, possibly explaining the differing associations between sexes. He also suggested that components other than fat in the food sources might contribute to this inverse association.
This study’s significance is that it challenges the idea that high fat intake is detrimental to longevity in women. Drastic dietary habits, such as extreme low-carbohydrate and low-fat diets, have become popular strategies for improving health and managing metabolic syndrome. However, this study suggests that these diets may not be the healthiest approach for long-term well-being.
Instead, the researchers recommend individuals carefully balance their diets, ensuring a variety of food sources while avoiding extremes. The findings emphasize the importance of considering the long-term implications of diet choices and avoiding the potential risks of restrictive diets.
In conclusion, this research highlights the potential risks associated with extreme dietary habits for carbohydrates and fats. Finding an optimal balance in one’s diet may be crucial for promoting longevity and overall health.
Source: Journal of Nutrition
Title: Extreme dietary habits for carbohydrates and fats affect life expectancy: findings from a large-scale cohort study in Japan
DOI: 10.1016/j.tjnut.2023.05.027