“Metabolic rate is really stable all through adult life, 20 to 60 years old,” said study author Herman Pontzer, an associate professor of evolutionary anthropology at Duke University and author of “Burn,” a new book about metabolism. “There's no effect of menopause that we can see, for example.
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.
As you age, your metabolism tends to decelerate by about 5% for every decade of life past age 40, so that if your resting metabolic rate is, say, 1,200 calories per day at age 40, it will be around 1,140 at age 50.
Less muscle, more fat: Women naturally lose lean body mass – or muscle – as they get older. Men do too, but women have less to begin with, so hanging on to it takes more effort. Having less muscle decreases your metabolic rate.
A slow metabolism has many symptoms, and you're likely to have one if you find it difficult to lose weight and easy to gain weight. Other symptoms include fatigue, poor digestion, constipation, low mood, and a colder than average body temperature. All of these are caused by the lower production of energy and heat.
Fat-burning ingredients like protein, spicy peppers and green tea have been proven to bump up metabolism. Eat some form of these foods, especially protein, at every meal. Protein is especially important: It takes more calories to digest than other foods and also helps the body build fat-burning lean muscle tissue.
Epidemiologists have observed that the average person typically puts on 1 to 2 pounds a year from early adulthood through middle age. The CDC's numbers show that much of the increase is concentrated in the 20s, for men and women.
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.
To boost your metabolism, try strength training and lifting weights. Building muscle mass also helps your body burn more calories, so you don't convert them to fat as easily. Weights, resistance bands, and body weight exercises can all help build muscle.
Loss of lean muscle – Around your 40s, and especially when you hit menopause, you'll likely start to lose muscle mass due to lower estrogen and testosterone levels. This can lead to weight gain due to the fact that muscle mass is one of the largest components of how many calories you burn each day.
As you get older, you lose muscle mass, which slows your metabolism and causes weight gain. So if your diet doesn't change, you are likely to gain weight.
The amount of body fat goes up steadily after age 30. Older people may have almost one third more fat compared to when they were younger. Fat tissue builds up toward the center of the body, including around the internal organs.
The finding of the study suggests that people in middle age certainly gain weight and it is harder for them to lose it, but slow metabolism is not the real reason behind it. It was revealed that from the 20s to the 50s the energy expenditure is the most stable.
As people gain weight, excess fat tends to be centered around the abdomen, generally starting at the lower abdominal area and working up. This results in a large belly or gut protruding out from the rest of your body.
Calcium, vitamin B5, vitamin B6, vitamin B12, vitamin B complex, and vitamin C: These provide nutrients that help you function better all around. These also improve metabolism to assist your weight loss: Green tea: Caffeine and catechins in green tea and other products may help with weight management.