By now, you know that to reach and maintain a healthy weight, you need to eat right and exercise. But ongoing research suggests that two other factors may also play a large role in how many pounds you carry: sleep and stress. Experts recommend 7 to 9 hours of sleep per night for adults, but many people get less than six hours. And as the amount of sleep Americans get has gone down in the past few decades, the obesity rate has gone up. Research even shows that persistent stress increases the amount of food people eat and may promote fat accumulation. How exactly do sleep and stress affect the number you see on your scale? Here’s what scientists know so far. When You’re Sleep Deprived… Your hunger hormones get out of whack. Not getting enough sleep can affect two hormones that regulate your appetite. Levels of leptin, the hormone that helps you feel full, go down. Meanwhile ghrelin, the hormone that makes you feel hungry, goes up. These changes may make you eat more food than you need, causing you to gain weight. You move less. Some studies suggest that people who don’t sleep well are less physically active during the day. Because you’re less active, you burn fewer calories. You have the nighttime munchies. When people are sleep deprived, they tend to eat smaller breakfasts but then overeat later in the day. In one study, sleep-deprived subjects ate more calories after dinner than they ate at any single meal. These late-night snack choices also tend to be high in carbohydrates and saturated fats, research shows. You’re more likely to give in to food temptations. Do you find it nearly impossible to resist food that’s in front of you? If so, you may be especially susceptible to the waist-expanding effects of short sleep. A study in the journal SLEEP found that people who sleep for short amounts of time who eat impulsively gained a significant amount of weight over time. A few extra hours awake at night often means a few extra hours munching on junk food, the researchers say. When You’re Stressed… Your body releases fat-storing hormones. In response to stress, your body releases the hormone cortisol. Cortisol promotes visceral fat, the dangerous type of fat that surrounds your organs. If you’re stressed too often, your body can release very high amounts of cortisol, which may play a role in weight gain. You soothe yourself with food. Delicious foods light up your brain’s reward systems and may help you feel better temporarily. But when stress is constant, some people cope by eating junk food regularly. It becomes a learned behavior. This can make it easy to consume more calories than you need. You have a hard time sleeping. Stress and worrying can make it hard to fall asleep at night. If this happens regularly, stress can cause sleep deprivation and all its waist-expanding consequences. Keep your bedroom a peaceful retreat free of work projects and other stress triggers. To fall asleep easier, make sure to relax before bedtime. A hot bath or shower is a good option. Not only is a shower relaxing, but it will also cause a sleepiness-inducing drop in your body temperature when you get out. If you have trouble sleeping for more than three weeks, talk with your doctor. Key Takeaways Poor sleep and persistent stress may cause you to gain weight. Not getting enough sleep can affect hormones that regulate your appetite, making you eat more food than you need. Some people cope with stress by eating junk food regularly. In response to stress, your body releases a hormone that promotes visceral fat. If you’re stressed too often, this can cause weight gain.