New research shows that lifestyle factors affecting breast cancer risk change depending on a woman’s age and life stage. A study analyzing data from over 110,000 women in the Breast Cancer Now Generations Study found that risk factors like alcohol use, smoking, physical activity, and weight gain vary throughout a person's life. Published in Scientific Reports, the findings suggest that adolescence and early adulthood are important times to encourage physical activity and avoid rapid weight gain. Meanwhile, early to mid-adulthood—roughly the 30s to 50s—may be a key period for managing body mass index (BMI) and limiting alcohol consumption. The study also found differences in lifestyle patterns between generations. Women born between 1960 and 2003 had higher BMI trends and reached peak smoking and alcohol consumption at younger ages compared to those born between 1908 and 1959. Researchers believe understanding these life stages can help women make long-term lifestyle changes to lower their breast cancer risk. According to the study, up to 23% of breast cancers could be prevented through healthy habits, such as regular exercise, maintaining a healthy weight, and reducing alcohol intake. In a separate study from The University of Manchester and Manchester University NHS Foundation Trust, researchers explored how weight changes over time might influence breast cancer risk. They found that women who were overweight in early adulthood might be less likely to develop breast cancer after menopause, possibly due to long-term changes in breast tissue structure. However, the researchers emphasized that weight gain is not a protective factor against cancer. Excess weight is actually linked to several types of cancer, and high BMI during middle age is associated with an increased risk of breast cancer. The study analyzed data from nearly 58,000 women in the UK PROCAS study, who were aged 46 to 73 when they joined. Researchers collected BMI data from when the women were 20 and compared it to their BMI in later adulthood. They found that those with higher BMI at age 20 had a lower risk of post-menopausal breast cancer, but those with higher BMI in later adulthood and higher breast density had an increased risk. Scientists believe the timing of weight gain matters, as breast tissue development during adolescence and early adulthood may lead to lasting structural changes in the breast.