18 Best Ways to Keep Weight Off If You're Over 40

The body starts to lose muscle mass after the age of 30, and inactive people can lose up to 5% of muscle mass over 10 years. Muscle plays a huge role in controlling your metabolism — you need muscle to burn calories. So if you want to lose weight, or not gain any, as you get older, you need to replace what’s lost. Studies have shown that eating more protein can help maintain or build muscle mass. As for exercise, strength training with weights or using your own body weight (squats, pushups, planks, wall sits) will do the trick, Metcalf, noted.

“Many of my clients are confused, [thinking] that if a workout is not an hour, then it’s not worth it,” Metcalf said. “This cannot be farther from the truth.” Studies have shown that you can get the same benefit in half the time. A study at the University of Copenhagen showed that moderately overweight men who exercised for half an hour a day lost 8 lbs. in three months compared to the 6 lbs. lost by those who exercised for an hour. The key is the intensity of the workout.

High-intensity interval training is the way to get a significant “calorie burn in the shortest amount of time,” Natalie Sandone, fitness instructor, said. Short periods of high-intensity exercise that engage many muscles require the body use a lot of oxygen during both the exercise and rest. And increasing oxygen demands increases calories expenditure during both phases, according to the American Council on Exercise. “You can pick whatever time frames you want, but recover only as long as you need to start pushing hard again,” Sandone added.

Being physically active as often as possible is important to maintaining a healthy weight. Going for a 10-minute walk both before and after dinner is an easy way to get some exercise in, Metcalf suggested. “Before — it may help decrease appetite, and after — it helps with digestion.” A study observing pre-diabetic people found that those who went for a walk after a meal had lower blood sugar spikes. Also, walking boosts metabolism because the body needs more energy.

The small butterfly-shaped gland controls many functions of the body, including metabolism speed. A person with an underactive thyroid could gain between 5 and 10 pounds of body weight, depending on the severity of the hormones deficiency. Thyroid hormones act on cells by increasing their activity, so if there are not enough of them, metabolic function is damaged. Causes for thyroid dysfunction vary from iodine deficiency and inflammation to cancer and even certain medications.

Lack of sleep and weight gain often go hand in hand, according to science. Short sleep durations have been linked to higher levels of ghrelin, commonly known as the “hunger hormone” because it increases one’s appetite, and to lower levels of leptin, a hormone that signals the brain you’re full. Research has shown that sleep-deprived people also consume more calories than usual, mainly from snacks, which tend to be rich in carbs, salt, and sugar. Lack of sleep messes with fat cells’ ability to respond to insulin, which regulates energy, eventually leading to weight gain. In addition, people who sleep less are more tired and less likely to exercise, which is linked to weight gain and obesity.