When it comes to women’s health, the scale alone doesn’t tell the full story. Even your BMI can overlook crucial factors that reveal your true wellness picture. What matters most is body composition—the ratio of muscle to fat in your body—which can directly influence your risk for diseases, including breast cancer.
According to recent research, excess abdominal fat plays a particularly concerning role. A Frontiers in Nutrition meta-analysis of nearly eight million women found that central obesity—measured by waist circumference or waist-to-hip ratio—was significantly linked to higher breast cancer risk in both pre- and postmenopausal women.
How Body Fat Increases Breast Cancer Risk
Fat tissue is more than just stored energy—it’s biologically active. Researchers have identified several key ways that excess fat can elevate breast cancer risk, especially after menopause.
1. Chronic Inflammation
Visceral fat (the fat surrounding internal organs) releases inflammatory molecules called cytokines. These promote low-grade, chronic inflammation that can damage cells and foster cancer growth.
2. Insulin Resistance
Being overweight can make your body less responsive to insulin, forcing it to produce more. Elevated insulin levels can stimulate the growth of breast cancer cells and prevent their natural cell death, according to studies in the Journal of Clinical Oncology.
3. Hormonal Imbalance
After menopause, fat tissue becomes the body’s main source of estrogen. Higher estrogen levels can fuel the growth of hormone-receptor-positive breast cancers, as noted in Scientific Reports.
Why Muscle Mass Matters Too
While reducing fat is vital, maintaining muscle mass is just as important for cancer prevention and survivorship. Research published in Discover Oncology found that women with lower muscle mass (sarcopenia) had significantly worse survival rates compared to those with normal muscle levels.
Healthy muscle mass helps combat inflammation, improves metabolism, and supports hormone balance—all factors that lower cancer risk. Incorporating strength training—like lifting weights or using resistance bands—can help preserve lean muscle while reducing body fat.
Tracking Body Composition for Prevention
Traditional weight or BMI measurements can be misleading. Body composition analysis, such as using an InBody scan, provides a more complete view by distinguishing fat from muscle and showing where fat is distributed.
Monitoring your results over time can help you identify trends, adjust your diet and exercise plan, and track progress toward a healthier balance. For many women, maintaining a waist circumference under 35 inches (88 cm) is a helpful goal.
Postmenopausal women, in particular, benefit from tracking lean mass and fat mass—since both inflammation and estrogen production from fat tissue can influence risk.
Lifestyle Strategies for a Healthier Body Composition
You can take actionable steps to improve your body composition and lower breast cancer risk:
Eat Anti-Inflammatory Foods
Emphasize colorful fruits and vegetables, whole grains, nuts, seeds, olive oil, and fatty fish. These foods calm inflammation and stabilize hormones. Limit alcohol, processed foods, and sugary drinks.
Strength Train Regularly
Combine resistance training with aerobic activity for best results. Aim for at least two strength-training sessions and 150 minutes of moderate exercise per week.
Prioritize Sleep and Stress Management
Poor sleep and chronic stress disrupt hormones and increase inflammation. Aim for 7–9 hours of rest and explore relaxation practices like meditation, yoga, or time outdoors.
The Bottom Line
Improving your muscle-to-fat ratio isn’t just about looking stronger—it’s a key strategy for long-term wellness and reducing breast cancer risk. By tracking your body composition and making sustainable lifestyle changes, you can actively support your health at every stage of life.
Original article by Jimmy Brown, published October 14, 2025. Read the full version on InBody USA’s blog.