A team of researchers at Nagoya University in Japan conducted a large-scale study to understand how dietary patterns relate to longevity for men and women. The findings suggest that gender-specific nutrition matters: women may benefit from a greater emphasis on healthy fats and a careful approach to carbohydrate intake, while men could see advantages from limiting fats and increasing carbohydrate consumption. The results were reported in a peer-reviewed journal focusing on nutrition science and public health.
Involving a substantial sample, the researchers analyzed data from 81,333 Japanese adults aged 35 to 69, with 34,893 men and 46,440 women participating. The group displayed BMI values that commonly fall within a healthy range, averaging 23.7 for men and 22.2 for women. Participants were followed for more than nine years, providing a long-term view of how dietary choices correlated with health outcomes over time. Dietary intake decisions were assessed using a comprehensive questionnaire that captured daily amounts of carbohydrates, fats, and total energy consumed.
The analysis revealed notable gender differences. Men whose diets drew less than 40 percent of total energy from carbohydrates faced a significantly higher risk of mortality in the study period. For women, the pattern was opposite: those whose diets contained more than 65 percent of energy from carbohydrates exhibited a higher risk of death. Importantly, the study found that the degree of carbohydrate processing—whether the carbohydrates came from refined white rice or from unrefined brown rice—did not substantially alter these associations with life expectancy. In other words, the source of carbohydrates did not mitigate the observed risks in either sex when the overall carbohydrate contribution was very high or very low.
When examining fat intake, distinct gender-specific trends emerged. Men who obtained more than 35 percent of their energy from fats showed an elevated risk of cancer-related mortality. This risk was particularly pronounced if their intake of unsaturated fats, which are abundant in fish, seafood, and plant-based foods, was low. On the other hand, higher fat consumption among women was linked to a lower risk of death, suggesting that fat sources and overall energy balance might interact differently in women compared with men when it comes to longevity outcomes.
The study also touches on a broader issue observed in many nutritional discussions: extremely restrictive dietary patterns that push very low levels of carbohydrates and fats are popular in some circles. While such approaches can lead to short-term improvements in certain health markers, the researchers urge caution by noting that long-term health risks could offset the initial benefits. These findings add nuance to the conversation about dieting, emphasizing that a one-size-fits-all strategy is unlikely to be effective for longevity and that gender-specific considerations may be important for personalized dietary guidance.
Beyond the core results, the researchers reflect on how people’s dietary choices are shaped by cultural and food system factors. In communities where staple foods are high in carbohydrates or fats, adjusting intake patterns may require practical, sustainable approaches rather than abrupt, drastic changes. The ultimate goal remains clear: to support healthier aging through balanced eating patterns that align with individual health profiles and lifestyle realities. While more research is needed to refine dietary recommendations, this study contributes valuable evidence about how men and women may experience different longevity implications from the same macro-nutrient distributions.
Current findings also align with a broader body of work exploring nutrition and metabolic health. The observed gender differences in how carbohydrate and fat intakes relate to mortality risk underscore the importance of considering sex as a biological factor in nutritional studies. The study does not claim that one nutrient is inherently good or bad for everyone, but rather highlights that the same dietary mix can have divergent health implications depending on sex and overall dietary context. This perspective supports a move toward more personalized nutrition guidance in public health messaging and clinical practice, aiming to optimize longevity while respecting individual dietary preferences and cultural practices.
The broader implication for individuals and health professionals is to approach dietary planning with nuance. Rather than pursuing extreme low-carbohydrate or low-fat regimens, attention should be given to balanced energy intake, the quality of macronutrients, and how dietary patterns interact with activity levels, genetics, and other health factors. In particular, opportunities may exist to tailor guidance to the needs of men and women separately, recognizing that optimal fat and carbohydrate balance might differ between the sexes to support long-term health and life expectancy. These insights reinforce the value of evidence-based nutrition that respects diversity in dietary patterns and aims for sustainable, healthful eating over the life course.
Researchers also note that ongoing exploration into nutritional biochemistry continues to reveal how foods influence disease risk and aging. As science advances, more precise recommendations can emerge, taking into account not only macronutrient ratios but also micronutrient adequacy, meal timing, and overall dietary variety. The study invites further inquiry into how personalized nutrition strategies can be implemented in public health programs and individualized care, with the shared aim of helping people live longer, healthier lives through informed, practical choices about what to eat.