In June 2013, the American Medical Association declared obesity—defined as having a body mass index (BMI) of 30 or higher—as a disease requiring multiple interventions for treatment and prevention. These can include behavioral modifications, medications and possibly surgery.

The numbers are jarring. According to statistics from the Centers for Disease Control and Prevention, more than one-third (36.5 percent) of US adults are obese, with more middle-aged (40.2 percent) and older adults (37 percent) being affected compared to younger adults (32.3 percent). On a global level, the World Health Organization states that obesity has more than doubled since 1980.

People who are obese have a higher risk of numerous conditions, such as:

• Diabetes
• Stroke
• Cardiovascular issues, including high cholesterol, lower levels of HDL [good] cholesterol, high blood pressure and heart disease
• Multiple types of cancer, including that of the colon, rectum, endometrium, kidney, pancreas and gallbladder—as well as breast cancer in women who have been through menopause

You probably know that overeating and a lack of physical activity contribute to obesity—but there are other risk factors that may not be as apparent.

While everyone gets anxious at times, ongoing mental and physiologic stress can cause the number on the scale to move in the wrong direction. A 2017 study published in the journal Obesity showed that chronic stress can lead to elevated levels of cortisol, a hormone that affects metabolism and helps the body manage stress. After taking a strand of hair that represented two months of hair growth from 2,527 adults aged 54 and older, scientists found that the volunteers with higher cortisol levels were also more likely to have a larger waist circumference, a higher weight and a higher BMI.

Obesity is connected to inadequate slumber. One review of sleep studies published in The American Journal of Human Biology detailed the links between inadequate sleep (defined as less than six hours) and increased BMI. Researchers found that a lack of shut-eye disrupted two hormones: ghrelin, which increases appetite, and leptin, which signals you're full. This disruption may lead you to eat more than you normally would, contributing to weight problems.