"The biggest thing people do that slows their metabolism down is eating too few calories," said Fiore. 1200 calories per day is roughly the amount you need to perform basic functions, she suggested, and when a person eats fewer than that, the metabolism slows down to conserve energy.
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.
Factors that may increase a person's metabolic rate include consuming an appropriate number of calories, favoring protein over carbohydrates and fat, getting enough sleep, and some types of exercise, such as resistance training.
A prolonged 1,200 calorie-per-day diet can slow metabolism, so it is best to only do it short-term. There are risks to consuming too few calories, including: Not getting adequate nutrition. Anxiety.
Metabolic rate remains stable all through adult life, from age 20 to 60 years old.
Caffeine increases your resting metabolic rate, which means it increases the number of calories you burn at rest.
Cardiovascular exercise (running, swimming, aerobics, walking) stimulates your metabolism, helps you burn calories and can even temporarily suppress your appetite post-workout.
Eating too few calories can be the start of a vicious cycle that causes diet distress. When you cut your calories so low that your metabolism slows and you stop losing weight, you probably will become frustrated that your efforts are not paying off. This can lead you to overeat and ultimately gain weight.
As a general rule, people need a minimum of 1,200 calories daily to stay healthy. People who have a strenuous fitness routine or perform many daily activities need more calories. If you have reduced your calorie intake below 1,200 calories a day, you could be hurting your body in addition to your weight-loss plans.
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.
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.
Poor sleep, sedentary activities, and eating too many processed or sugary foods are just some of the habits that may increase your risk of weight gain. Yet, a few simple steps — such as mindful eating, exercise, and focusing on whole foods — can help you reach your weight loss goals and improve your overall health.
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.
If you're consuming too few calories your body essentially goes into starvation mode and receives the message that it needs to protect itself. This means holding onto weight for protection's sake. The body perceives reduced calorie intake as a stressor.
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.
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.