Obesity risk factors: habits, sleep, medicines and genes

What obesity is

Obesity is a disease that means having too much body fat. It is different from being overweight, which means weighing too much. Both terms mean that your weight is greater than what's considered healthy for your height (MedlinePlus).

Body mass index (BMI) measures how much you weigh compared to how tall you are. An adult who has a BMI of 30 or more is considered to have obesity, and severe obesity is having a BMI of 40 or higher (MedlinePlus). You can work out your BMI with our BMI calculator or look it up on the BMI chart. BMI does not distinguish between fat, muscle, and bone mass, and a large waistline, with more body fat around your belly rather than your hips, increases your risk for weight-related health problems (MedlinePlus).

How obesity develops

Overweight and obesity can develop over time when you consume more calories than you use, an energy imbalance that causes your body to store more fat than it can use (NHLBI). But your risk is determined by more than how much you eat. It also includes the types and amount of food and drinks you consume each day, your level of physical activity, and how much good-quality sleep you get each night (NHLBI).

Some risk factors are individual factors like knowledge, skills, and behaviors. Others are in your environment, such as school, workplace, and neighborhood. Food industry practices and marketing, as well as social and cultural norms and values, can also affect your risk (NHLBI).

What raises the risk of obesity

MedlinePlus lists certain medicines or medical conditions, and your genetic makeup, eating habits, sex, race or ethnicity, and physical activity level (MedlinePlus). The NHLBI and NIDDK describe these factors:

• Lack of physical activity: lack of physical activity, combined with high amounts of TV, computer, video game, or other screen time, has been associated with a high BMI (NHLBI). Spending a lot of time sitting or lying down is a habit that may lead to weight gain (NIDDK).
• Eating habits: eating more calories than you use, eating too much saturated fat, and eating foods high in added sugar (NHLBI), and drinking a lot of beverages that are high in added sugars (NIDDK).
• Not getting enough good-quality sleep: regularly getting less than 7 hours of sleep per night can affect the hormones that control hunger urges (NHLBI). Not getting enough sleep may make you feel hungrier, consume more calories, and be more likely to choose unhealthy foods and beverages (NIDDK).
• Stress: long-term and even short-term stress can trigger your body to make hormones, such as cortisol, that can make you eat more and store more fat (NHLBI).
• Health problems: some endocrine diseases, such as polycystic ovary syndrome (PCOS), Cushing's syndrome, and hypothyroidism; damage to the hypothalamus; depression; and long-term stress. Some eating disorders, such as binge-eating disorder and bulimia nervosa, may also lead to obesity or weight gain (NIDDK). The NHLBI also names metabolic syndrome (NHLBI).
• Genes and family history: researchers have found at least 15 genes that influence obesity (NHLBI). Your chances of having overweight or obesity are greater if one or both of your parents have overweight or obesity, and genes may also affect how much fat you store, where on your body you carry it, your appetite, and how physically active you are (NIDDK).
• Where you live and work: people living in neighborhoods with more fast food restaurants and inaccessible or no sidewalks or bike paths are more likely to be overweight or obese, while access to sidewalks, green spaces, grocery stores and farmers markets can help people be more active and eat healthier (NHLBI).

Medicines that can cause weight gain

Some medicines cause weight gain by disrupting the chemical signals that tell your brain you are hungry, or by making your body burn fewer calories (NHLBI) (NIDDK). The NHLBI and NIDDK lists include:

• some medicines for depression, epilepsy, or psychotic disorders
• corticosteroids (glucocorticoids)
• some diabetes medicines, such as insulin and sulfonylureas
• some blood pressure medicines, such as beta-blockers, alpha-blockers, and calcium channel blockers
• birth control
• some antihistamine medicines used to treat allergy symptoms

Talk to your provider if you notice weight gain while you are using one of these medicines. Ask whether there are other forms of the same medicine or other medicines that can treat your condition but have less of an effect on your weight (NHLBI).

Obesity in pregnancy and childhood

Children whose mothers had obesity during pregnancy are more likely to have obesity themselves, and children and adolescents who have obesity are more likely to have obesity as adults (NIDDK). MedlinePlus lists pregnancy problems and fertility problems among the health problems obesity may raise the risk of (MedlinePlus).

Health problems obesity can cause

Having a larger body size can make your heart work harder, put extra pressure on your joints, and may increase your risk for many health conditions, including (MedlinePlus):

• type 2 diabetes
• heart disease
• high blood pressure
• stroke
• metabolic syndrome
• osteoarthritis
• sleep apnea
• pregnancy problems and fertility problems
• some cancers

If you have obesity, losing even 5 to 10% of your weight can delay or prevent some of these diseases. For example, that means losing 10 to 20 pounds if you weigh 200 pounds (MedlinePlus).

Lowering your risk

You may not be able to change all of your risk factors for overweight or obesity, but knowing your risk is important to help you take steps toward a healthy weight (NHLBI). For people with a genetic high risk for obesity, making healthy lifestyle changes can help lower that risk (NHLBI). Most adults need at least 150 minutes of aerobic activity a week, and children should get 60 minutes of aerobic activity each day (NHLBI). Experts recommend that adults ages 18 to 64 get 7 to 9 hours of sleep a night, and adults 65 and older 7 to 8 hours (NIDDK).

Common questions

Is obesity genetic?

Partly. Researchers have found at least 15 genes that influence obesity, and genetics may play a more important role in people with obesity than in people who are overweight (NHLBI). Lifestyle habits, sleep, medicines, health problems and where you live also affect weight (NIDDK).

What BMI counts as obesity?

For adults, a BMI of 30 or more is considered obesity, and 40 or higher is severe obesity (MedlinePlus).

Does lack of sleep cause weight gain?

Not getting enough sleep is linked to weight gain (NIDDK). Regularly getting less than 7 hours a night can affect the hormones that control hunger (NHLBI).