You've probably been told the following: Once-fast metabolism slows way down in your 30s.

Over time, the scale tends to rise and our jeans get tighter or stop fitting. You may feel pressured to spend more time at the gym and change your diet to fight back. From a young age, we're taught that our metabolism is a constant uphill battle.

Recent research contradicts that.

Experts believed that a person's metabolism slowed in their 30s, 40s, 50s, and beyond, leading to weight increase. Science research shows that's not true. A 40-year study of 6,500 males and girls aged 8 days to 95 indicated that our metabolisms remain stable from 20 to 60. After age 60, calorie-burning slows by just 7% every decade. A body that burns 1,400 calories per day at 60 will burn 1,300 by 70.

Your body isn't working against you to maintain a healthy weight. Except… Age-related weight gain still happens, as anyone who's glanced at old photos knows. JAMA reports that the average American gains 1 to 2 pounds every year until age 55. But aging isn't to blame. Our behaviors change with age, making it simpler to gain fat, says metabolism researcher and author Herman Pontzer, Ph.D.

So what does this mean? In short, your metabolism isn’t slowing down -- you are. For many people, “aging” really means eating more and moving less. To avoid this trap and support your body's calorie-burning potential at any age, curb unhealthy habits now so that extra calories won’t pack on extra weight. Here are five science-backed ideas to try today.

1. Eat more mindfully

The meals we eat affect our metabolism and body function, but there is no magic food. It's simple to grab snacks when you have them around “just because.” Eating feels good, and hey, they’re there, right? Well, Pontzer believes most of us aren't actually hungry many times -- we’re just eating on autopilot -- and those extra bites can lead to overeating and weight gain. Distracted eating causes people to consume 10% more calories in the moment and 25% more calories at later meals, a study found.

That doesn't mean you have to give up your favorite foods. You only need to consume them more carefully. Mindful eating expert and author Susan Albers, Psy.D., recommends to focus on why you're eating rather than what. "Mindful eating can help you lose weight," she says.

It's as simple as verifying if you're truly hungry before eating.

2. Eat filling foods

Pontzer says choosing foods that keep you full longer can help you lose weight. When you're full after a meal or snack, you're less likely to eat again soon.

What should be on the menu, usually? Focus on protein, fiber, and healthy fats. To understand why, imagine your metabolism and digestion as a fire that needs to be fed properly, explains Seattle nutritionist Liz Wysonick, M.S., R.D.N. Protein, fiber, and healthy fat are like fire-friendly fuel logs because they're processed slowly, she explains.

White bread, white spaghetti, and baked products aren't as useful and may have the opposite impact. Because they're quickly digested, they cause blood sugar to surge and dip, leaving you hungry soon after eating.

Occasional cookies and muffins are fine. Too many refined carbs may fool the brain into thinking the body is fasting by affecting blood sugar levels. A report in the American Journal of Clinical Nutrition reveals that this causes the body to retain carbohydrate calories as fat while encouraging you to consume more.

The solution? Choose fiber-rich whole grains like brown rice or whole wheat pasta over processed alternatives and pair them with a protein (like beans or fish), a healthy fat (like olive oil or avocado), and a dish of veggies or fruit. Wysonick recommends produce-plus-protein snacks. Greek yogurt with berries, hummus and crudite, or apple slices with peanut butter work. Save sweets for special occasions (think once or twice a week instead of every day).

3. Exercise

Regular strength training preserves and builds lean muscle, which burns more calories than fat tissue. Lara Dugas, Ph.D., studies exercise physiology and metabolism at Loyola University Chicago. "The longer you can maintain muscular mass, the longer your metabolism will last."

For example, PLoS Medicine discovered that men and women with normal BMIs who do one to two hours of resistance training each week are 30% less likely to become obese after nearly two decades. The CDC recommends working all main muscle groups twice a week.

Even while calorie-burning doesn't drop until our 60s, you'll receive more benefits by working out in your 20s or 30s. After 60, it's hard to regain lost muscle. Dugas says, "It's easier to maintain than rebuild."

4. Do cardio, but not too much

Aerobic exercise boosts your daily calorie burn, which can help you lose weight when combined with a healthy diet. Physical activity mixed with a balanced diet will help you reach a healthy weight more than either alone.

Thirty minutes of moderate aerobic exercise five days a week (or 75 minutes of intense exercise) is recommended, but don't overdo it for the scale, adds Dugas. Going beyond 150 minutes of physical activity per week doesn't seem to help to weight maintenance or weight loss over the long run, an American Diabetes Association assessment found. Why? Studies show that exercising more may cause you to eat more, leaving you where you started. (One-hour runs make you hungry!)

Walking, cycling, and jogging are good starting points. Dugas advocates working up to high-intensity interval exercise (HIIT). It promotes calorie-burning after exercise, "so it's helpful for weight loss," she explains.

Outside of planned sweat sessions, sit less, stand more, and move more. Even regular exercisers burn fewer calories sitting for long periods. Frequent walking or standing breaks, pacing, or fidgeting can help your body burn extra energy all day, a Mayo Clinic Proceedings review found.

5. Manage stress and sleep

To boost your body's ability to burn calories, think holistically—beyond eating and exercising. Stress and lack of sleep might hinder healthy decision-making. Stress and tiredness can increase sugar cravings and kill your enthusiasm to stay active, leading to weight gain, a 2018 study found.

Stress hormone cortisol rises when we're harried or sleep-deprived (or both), says sleep medicine doctor Thomas Bradley Raper, M.D. Bad sleep won't add pounds, of course. Harvard Medical School says that chronic stress might cause cortisol levels to "stick" high, leading to weight gain.

People's paths to calm can vary. Taking breaks when you're stressed, doing things you enjoy, and putting down your phone or other electronics can all help reduce stress, according to the CDC. Once you're more relaxed, getting the necessary seven to eight hours of sleep and making healthy choices may be simpler.