The general idea is always that obesity is an important cause of various human diseases, and even fat people have a higher mortality rate than normal weight, but in recent years there is also a theory of “obesity paradox”, citing a study in 2012, pointing out that “fat people” are healthier than “normal” weight people, the study shows that whether overweight or mild obesity (according to the BMI index), fat people have a 6% lower risk of death than normal weight people. The risk of death is 6% lower than that of normal weight people. The higher the BMI of young women, the lower the risk of breast cancer. This “obesity paradox” was recently supported by an alternative breast cancer study conducted by a team of researchers from the University of North Carolina in the United States, which collected data from 19 different studies on nearly 760,000 women under the age of 55 who had been investigated for breast cancer. The analysis showed that the higher the body mass index (BMI), the lower the risk of breast cancer in young women, representing the advantage of obesity in favor of avoiding breast cancer. The results of this study show an interesting association between obesity, age and the risk of breast cancer. The greatest reduction in breast cancer risk was seen in women between the ages of 18 and 24, with a 23% reduction in breast cancer risk for every 5 unit increase in BMI, while women between the ages of 25 and 34 had a 15% reduction in breast cancer risk for every 5 unit increase in BMI, women between the ages of 35 and 44 had a 13% reduction in breast cancer risk for every 5 unit increase in BMI, and women between the ages of 45 and 54 had a 13% reduction in breast cancer risk for every 5 unit increase in BMI. For women in the 45 to 54 age group, a 5 unit increase in BMI is associated with a 12% reduction in breast cancer risk. What is the link between estrogen and breast cancer and BMI? The team hypothesized that there may be several factors that contribute to the association between higher BMI and lower breast cancer risk in younger women, such as hormones (including estrogen), growth factors, or differences in breast density. Among these, estrogen has been shown to be a causal factor in breast cancer, but the levels and sources of estrogen vary before and after menopause, where the source of estrogen is primarily the ovaries, and estrogen produced by adipose tissue may help reduce estrogen produced by the ovaries. Nichols, who led the research team, pointed out that the amount of estrogen produced by the ovaries is driven by the body’s “feedbackloops”. will be higher. The study does not encourage women to gain weight to prevent breast cancer Although the team concluded that younger women who are obese have a lower risk of breast cancer, they cautioned that their study does not support or encourage women to gain weight to prevent breast cancer, and concluded that there are many health benefits to weight control. They also said that the causes of breast cancer in younger women may be different from those in older women, and that further research is needed to understand the specific causes of breast cancer in younger women.