The Impact of Carbohydrate and Fat Intake on Lifespan in Men and Women
A recent Japanese study suggests that extreme dietary habits related to carbohydrate and fat consumption may affect longevity. The research, conducted by Nagoya University Graduate School of Medicine in Japan, found that men who consume too few carbohydrates daily may increase their risk of dying. On the other hand, women who consume insufficient quantities of fat may face the same risk. The study involved participants who were in good health at the time of recruitment.
The study found that men who ate too few carbohydrates had a significantly increased risk of all-cause mortality. Women who consumed too little fat had a marginally higher risk of all-cause and cancer-related mortality. The research paints a complex picture of healthy eating in terms of carbohydrates and fats, suggesting that going to any extreme may negatively affect longevity.
In terms of carbohydrate consumption, men who got fewer than 40% of their daily calories from carbohydrates were at a significantly higher risk of all-cause mortality. For women, those who got more than 65% of their calories from carbohydrates were at a higher all-cause mortality risk. The study found no significant difference between the effect of consuming minimally processed carbohydrates versus refined carbohydrates.
Regarding dietary fat, men who got more than 35% of their calories from any kind of fat were at a higher risk of cancer and cardiovascular mortality. For women, consuming more fats, particularly saturated fats, decreased their risk of all-cause and cancer mortality.
The study involved 34,893 men and 46,440 women, ranging in age from 35 to 69 years. The average body mass index (BMI) for men was 23.7, and for women 22.2, within the healthy range.
Michelle Routhenstein, a cardiology dietician not involved in the research, stated that low carbohydrates in diet and low-fat weight loss diets for women can decrease longevity. Clinical nutrition epidemiologist Prof. Linda Van Horn, also not involved in the study, expressed concern that Americans may misinterpret the study’s findings.
In the United States, nearly one in three adults qualify as having overweight, and two in five qualify as having obesity. Dr. Van Horn added that the U.S. Dietary Guidelines take all these considerations into account and are far more reliable than attempting to extract meaningful applications from this cohort study.
The study suggests a shortfall in bioactive dietary components may be at play, such as fiber, heme iron, vitamins, minerals, branched-chain amino acids, fatty acids, and phytochemicals. A diet lacking in plant sources has been seen to encourage inflammatory pathways, cause more rapid biological aging, and produce oxidative stress.
The study supports the need for further research. For people in the U.S. and other Western countries, a similar study done with a more locally representative population may provide more actionable findings that consider the local dietary and health landscape.