If you’re overweight, you probably don’t need someone to tell you that excess weight is bad for your health. But understanding how and why fat affects all the systems of your body can be a powerful motivator for weight loss — particularly when the going gets tough.
So first, what is obesity? A person who has a body mass index of 30 or higher is considered obese and 25 or higher is considered overweight, according to the U.S. Centers for Disease Control and Prevention. BMI is by no means a perfect measure — it does not fully measure body fat, so some people, particularly athletes, might have a BMI that classifies them as overweight when they do not have an unhealthy amount of body fat — but knowing your BMI is a good starting point for any weight-loss program.
Another good measure is waist circumference, says Georgia Giannopoulos, RD, CDN, CNSC who works at New York-Presbyterian Hospital/Weill Cornell Medical Center. “The general guidelines say that a man should keep his waist circumference less than 40 inches, and a woman should keep hers less than or equal to 35 inches,” she says. Waist circumference is key because numerous studies have linked an excess of belly fat to an increased risk of conditions, such as heart disease and diabetes.
“Obesity adds a lot of stress to your body,” Giannopoulos says. “And obesity increases your risk of developing some diseases, including type 2 diabetes, heart disease, and hypertension.”
Fat literally weighs you down, adding additional wear and tear to most of your internal organs, bones, and joints. In addition to type 2 diabetes, heart disease, and hypertension, obesity also raises your risk for:
- Cancer. Colon, breast, and other cancers have been linked to obesity. And once you have cancer, obesity can make your prognosis worse. A study recently published in the journal Cancer Research found that obesity spurs the growth of cancer cells, possibly explaining why obese patients with cancer fare worse than normal-weight patients.
- Sleep apnea. An alarmingly common condition in a sleep-deprived country, sleep apnea causes breathing to temporarily stop during sleep, leading to constant fatigue and daytime sleepiness. The condition has also been linked to type 2 diabetes.
- Arthritis. One in three obese adults have arthritis, CDC data reports, and arthritis rates are projected to worsen as the nation continues to gain weight. It’s because obesity stresses the joints, leading to additional wear and tear and ultimately arthritis.
- High cholesterol. High cholesterol is often hereditary, but it is exacerbated by obesity, particularly in women, studies show. High cholesterol can lead to heart disease and other health problems, such as gallstones.
- Fatty liver disease. Obesity has long been associated with fatty liver disease, the most common liver disease in the world, which is caused by an excess of visceral or internal fat.
- Depression. Depression and obesity go both ways: People with depression have double the risk of obesity as their non-depressed peers while many people who are overweight report self-esteem or emotional health issues.
These reasons and more are why — in a country where two-thirds of adults are overweight or obese, heart disease is the No. 1 cause of death, and 26 million people have diabetes — bringing weight down to a healthy level is so essential for so many people.
“Weight loss might help control diseases that people have that could be worsened by obesity or reduce someone’s risk of different diseases,” Giannopoulos says. She notes that obesity has different causes in different people, and the best approach to weight loss is an individualized plan tailored to your needs.
“There’s not a quick fix out there,” she says. “It’s going to take some time, which is why it’s important to stay motivated throughout using the healthy lifestyle habits that will not only help you lose weight, but also maintain that weight loss for their lifetime.”