Some research suggests that susceptibility to permanent weight gain seems to be highest during adolescence, pregnancy, and midlife for women and the period after marriage for men.
A new study released by the CDC shows that adults over 60 years old were more likely to be obese than younger adults.
That may be due to a decades-long slow and steady "energy imbalance. The concept of energy imbalance is easy: Eat more calories than you burn and you will gain weight. Eat fewer and you will lose weight. It could be as little as a two extra sodas every month or a few too many neglected minute evening walks. It turns out that for most people, age-related weight gain is due in large part to a dramatic decrease in calories burned. While lower levels of physical activity play a large role in the decreased energy expenditure, an age-related decline in metabolic rate is also to blame.
A study evaluating total energy expenditure TEE — the sum of calories burned from the basal metabolic rate metabolism , the energy required to digest and absorb food, and physical activity — confirmed what most people already know: energy expenditure decreases with age. Basal metabolic rate, which accounts for about 50 to 70 percent of TEE, is thought to decrease about one to two percent per decade. That is, after a person reaches 20 years old, daily energy expenditure decreases about calories per decade.
The decline is probably due to decreased muscle mass which is highly metabolically-active and increased fat mass which is relatively metabolically-inactive. Some studies have also found that, even when controlling for fat-free mass, basal metabolic rate is five percent lower in older compared with younger adults.
It is not clear why, but some researchers speculate that it may be due to an unavoidable loss of very metabolically-active organ tissue, or a decreased metabolic rate within muscle tissues. Decline seems to be most rapid after 40 years old in men and 50 years old in women. In sum, the number of calories burned per day decreases with age. This reality is widely accepted and is even built in to formulas that estimate resting energy expenditure. And this was the first time that we had the ability to do this with a really big data set that would allow us to pull apart the effects of body size and age and gender and all these things on our energy expenditures over the day.
Take, for instance, the finding that metabolic rate declines in seniors, which might have been expected. We can say, 'No, no, no, it's more than that. Results did not show that metabolic rates spiked upward during the teen years or pregnancy, as commonly thought, or that there were specific differences between men and women after accounting for body size and composition.
Registered dietitian Colleen Tewksbury, a senior research investigator at the University of Pennsylvania and a spokesperson for the Academy of Nutrition and Dietetics, said the new study is surprising.
But if changing metabolism is not playing a role in weight gain at certain points in adult life, there could be other contributing factors, she said. It's more likely a much more complex web of lots of different changes happening at once. So that could be changes to food intake. Surprisingly, the growth spurts of adolescence didn't generate an increase in daily calorie needs after researchers took body size into account.
Another surprise? People's metabolisms were most stable from their 20s through their 50s. Calorie needs during pregnancy grew no more than expected. The data suggest that our metabolisms don't really start to decline again until after age The slowdown is gradual, only 0. But a person in their 90s needs 26 percent fewer calories each day than someone in midlife.
Lost muscle mass as we get older may be partly to blame, the researchers say, since muscle burns more calories than fat. But it's not the whole picture. After 60, a person's cells slow down," Dr.
Ravussin said. Aging goes hand in hand with so many other physiological changes that it has been difficult to parse what drives the shifts in energy expenditure. But the new research supports the idea that it's more than age-related changes in lifestyle or body composition.
But massive data sets like the one we collaborated on allow us to answer questions we couldn't address," Dr. It is shown that glucose tolerance decreases with age. Although age contributes independently to the deterioration in glucose tolerance, the decrease in glucose tolerance may be partly prevented through changes of life-style variables, energy metabolism is essential for the physiological functions.
It may also be possible to delay the aging process of various physiological functions by change of dietary habits, stopping smoking, and physical activity.
Abstract Age is one of the most important factor of changes in energy metabolism.
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