Yes. In the Nurses' Health Study of more than 115,000 women, as a woman's BMI increased, so did her risk of dying from heart disease.21 In this study, obese women had about 4 times the risk of dying from heart disease as normal-weight women. Overweight and obesity can also affect your risk of heart disease indirectly by increasing your likelihood of developing risk factors for heart disease. These risk factors include 22, 23:
- High blood pressure: Obese women are nearly 3 times as likely to have high blood pressure as those who are at a healthy weight. Overweight women are nearly twice as likely. Weight loss can lower your blood pressure if you are overweight or obese.22, 23
- Diabetes: Diabetes is a condition where a person's body either doesn't make enough, or doesn't respond to insulin—the chemical in the body that regulates how sugar is used and stored. Overweight women are more than twice as likely to develop type 2 diabetes as people who are not overweight.22, 23 Weight loss can lower your risk of developing diabetes if you are overweight or obese.
- High cholesterol: Excess fat sends chemical signals that affect how we digest our food. It raises our LDL (bad) cholesterol and lowers our HDL (good) cholesterol, causing fatty plaques to build-up along the walls of blood vessels and lead to heart disease. Weight loss can improve your cholesterol levels if you are overweight or obese.22 23
Being overweight is one step towards developing the metabolic syndrome.23, 24 Metabolic syndrome is a group of risk factors for heart disease that tend to occur together. These include a large waistline, and higher than normal blood sugar, blood pressure, and triglyceride levels.24, 25 Obesity can also activate parts of the inflammatory response—the body's response to injury—which increases the level of a chemical called C-reactive protein (CRP) in your blood.26, 27 Having high levels of CRP may increase your risk of heart disease.
Overweight and obesity also increase the risk of many other health problems such as breast, colon, and uterine cancer, osteoarthritis, and breathing problems.28
Why does the excess weight have such unhealthy effects on my heart?
Overweight and obesity can lead to risk factors for heart disease, but the extra pounds also take their toll on the heart directly. When a body becomes larger, the heart has to work much harder to move the blood around the body. Like an overworked pump, the hearts of overweight and obese people can simply wear out more quickly.29,30
Didn't a recent study show that being overweight isn't that bad?
You may have heard about a 2005 study that suggested there were actually a lot fewer deaths due to obesity than previously thought and that being overweight was really not so bad for your health.31 Several flaws in this study have since been pointed out: for example, the researchers did not properly account for smokers who tend to be slim but have greater health risks and they included people in the study who were possibly thin because of a serious illness. In reality, many more studies have shown that being overweight increases your chances of developing serious health problems and dying young, particularly from heart disease.21, 3, 22