Excess body weight, including both overweight and obesity, is linked to an increased risk of several types of cancer. The primary distinction between the two is based on body mass index (BMI): overweight is defined by a BMI of 25-29.9, while obesity is defined by a BMI of 30 or more. Studies have shown that excess weight can significantly raise the likelihood of developing certain cancers, including:
- Breast cancer (in women post-menopause)
- Colon and rectal cancer
- Endometrial (uterine) cancer
- Esophageal cancer
- Gallbladder cancer
- Kidney cancer
- Liver cancer
- Ovarian cancer
- Pancreatic cancer
- Stomach cancer
- Thyroid cancer
- Multiple myeloma
- Meningioma (a tumor of the brain and spinal cord lining)
In addition to these, excess body weight is also associated with other cancers such as non-Hodgkin lymphoma, male breast cancer, cancers of the mouth, throat, and voice box, and aggressive forms of prostate cancer. The link between excess weight and cancer is stronger for some types, such as endometrial cancer, where more than half of cases are thought to be related to excess weight, while the association is less pronounced for other cancers.
How Does Excess Body Weight Increase Cancer Risk?
Excess body weight might increase cancer risk through various mechanisms, some of which may be specific to certain types of cancer. These include:
- Inflammation: Chronic low-level inflammation associated with excess body fat can contribute to the development of cancer.
- Hormonal imbalances: Elevated levels of insulin and estrogen in those with excess weight can fuel cancer cell growth.
- Growth factors: High levels of insulin-like growth factor-1 (IGF-1), which is associated with cell growth, may play a role.
- Blood vessel growth (angiogenesis): Excess weight may encourage the growth of new blood vessels that tumors need to spread.
- Immune response changes: Alterations in the immune system can make the body more vulnerable to cancer.
In some cases, the timing of weight gain matters. For instance, women who are overweight as teenagers might face a higher risk of developing ovarian cancer before menopause, compared to those who gain weight later in life.
Does Losing Weight Reduce Cancer Risk?
While research on how losing weight specifically reduces cancer risk is still limited, there is growing evidence suggesting that intentional weight loss may lower the risk for certain cancers, such as breast and endometrial cancer. Studies indicate that weight loss can reduce levels of hormones like insulin and estrogen, which are linked to cancer development.
Even a modest amount of weight loss can provide health benefits beyond cancer risk reduction. It can improve heart health, reduce the risk of diabetes, and lower overall mortality. However, unintentional weight loss, which may signal an underlying health issue like cancer, should be taken seriously and investigated.
Other Health Risks of Excess Body Weight
Excess body weight not only raises the risk of cancer but also contributes to several other serious health conditions, such as:
- Heart disease
- Type 2 diabetes
- High blood pressure
- Stroke
- Gallbladder disease
- Sleep apnea
- Arthritis
- Mental health issues like depression and anxiety
Individuals with excess weight tend to have a lower quality of life and may not live as long as those who maintain a healthy weight.
How Common is Excess Body Weight?
In the United States, the rise in excess body weight can be attributed to poor eating habits, larger portion sizes, and decreased physical activity. About 40% of adults now have obesity, and this problem is affecting children as well, with 1 in 5 children and teens being classified as obese. This marks a significant increase over previous decades, although the rate has leveled off in recent years.
Excess body weight in children and teens can lead to the same health problems seen in adults, including heart disease risk factors, type 2 diabetes, and mental health issues like anxiety and depression. Children with obesity are also more likely to carry excess weight into adulthood, raising their future risk for health complications.
Recommendations for Maintaining a Healthy Weight
The American Cancer Society recommends that individuals aim to reach and maintain a healthy weight throughout their lives. The best approach to maintaining a healthy weight is balancing calorie intake with physical activity. If someone is already overweight, focusing on healthy eating and increasing physical activity can help them achieve a healthier weight.
A healthy eating pattern includes:
- Reducing calorie intake by eating more nutrient-dense foods like vegetables, fruits, whole grains, and beans
- Avoiding foods high in calories, fats, and sugars, such as fried foods, cookies, and sugary drinks
- Eating smaller portion sizes and limiting snacking between meals
The American Cancer Society also recommends adults get at least 150 to 300 minutes of moderate-intensity exercise per week, or 75 to 150 minutes of vigorous-intensity activity. This can help reduce the risk of cancer and improve overall health.
For Those Already Diagnosed with Cancer
Excess body weight is also linked to a higher risk of cancer recurrence and can negatively impact survival. Therefore, maintaining a healthy weight during and after cancer treatment is crucial. If a person with cancer is overweight, working towards a healthier weight can improve their health outcomes. In cases where malnutrition is a concern, such as during cancer treatment, gaining or maintaining weight through proper nutrition may be more important.
If weight loss is part of the goal, it should be done in a safe, controlled manner through a balanced diet and increased physical activity. Even modest weight loss can yield significant health benefits, particularly in terms of improving survival rates and overall well-being.
In conclusion, maintaining a healthy weight throughout life is crucial for reducing the risk of cancer, improving treatment outcomes, and enhancing overall health. Encouraging healthier eating habits, increasing physical activity, and supporting weight loss efforts are essential strategies in the fight against cancer and other chronic diseases.