Over time, studies have shown that metabolic rate (how fast we burn calories) starts to slow down by 2 to 3 percent each decade, beginning in our 20s. It becomes more noticeable between ages 40 and 60.
Your metabolic rate does change during your early life, but it plateaus between the ages of 20 and 60, and only decreases by around 1% per year after that. Your total daily energy expenditure also depends on your weight.
Your metabolic rate peaks in your early 20s, according to Women's Health Magazine. At this age, you tend to have a higher muscle mass and have a fair amount of physical activity built into your day. As early as age 30, however, men and women begin noticing a dip in their ability to lose weight.
Hormones
A shift in your hormones can put the brakes on your body's energy use. That can make you tired. Some conditions, like an underactive or overactive thyroid and diabetes, are hormonal diseases that affect your metabolism. Stress also releases hormones that can trigger a slow-down.
Luckily, a slow metabolism isn't permanent, and with the right changes to your diet and lifestyle, you can rev up your metabolism — and get back to feeling better in the process.
But another 120-pound person may have a lot less lean mass and more body fat and therefore a “slow” metabolism. In fact, it is possible to have “normal-weight obesity” – a term used when referring to a person who appears thin but who is not very active and therefore has very little muscle mass, Majumdar explained.
As we age, our metabolism slows and the rate at which we break down food decreases by 10 percent each decade after age 20. Metabolism is the amount of energy (calories) your body uses to maintain itself.
The rate of living theory postulates that the faster an organism's metabolism, the shorter its lifespan.
Study shows that younger people and women are more likely to put on extra pounds. A study that examined the long-term weight gain of more than 13,800 U.S. adults found that on average, people gained about 17 pounds between their twenties and thirties.
Aerobic activity can help control weight and can lower your risk of heart disease, diabetes, and many other conditions. Muscle-strengthening exercises are important for the same reasons but will also boost your metabolism.
Two common signs that you may be experiencing metabolic damage are dieting and exercising but not seeing any change in weight. Or, you may have been making progress with a diet or an exercise program but suddenly this progress stops.
The higher your metabolic rate, the more calories you burn performing these chemical processes. A fast metabolism can help with weight loss, as it means you can eat more calories while still burning fat and dropping weight. But having a slow metabolism isn't necessarily a bad thing.
Water is the key to life, and it turns out it's also one of the easiest ways to help your metabolism. Drinking water increases your metabolism by up to 25% for nearly an hour after drinking it. That means if you drink a few cups of water every hour, you'll keep your metabolism at peak performance all day.
Coffee Can Increase Your Metabolic Rate
Studies show that caffeine can increase RMR by 3–11%, with larger doses having a greater effect ( 11 , 12 ). Interestingly, most of the increase in metabolism is caused by an increase in fat burning ( 13 ). Unfortunately, the effect is less pronounced in those who are obese.
It simply takes time. Another common reason why people report not losing weight despite reducing their calories is that they don't give it enough time. Our bodies will do their utmost to hold on to our fat reserves and you often have to be in a calorie deficit for a while before you will see any meaningful weight loss.
You've gained muscle.
And here's an often overlooked fact: Muscle tissue is more dense than fat tissue. So as you gain more muscle and lose fat, you change your overall body composition, which can result in a higher weight, but a smaller figure and better health.