You might have heard people in their 30s complain that their metabolism isn’t the same after their 20s; but some research suggests the amount of energy our body naturally burns peaks at roughly 20, and stays the same ’til our 60s.
Still, it is true that muscle mass starts to wane in our third decade. Most people will continue to lose as much as 3-5% of lean tissue per decade, which can affect your energy efficiency.
But a paper published in the journal Nature Ageing suggests those changes ― and other signs of ageing ― aren’t spread evenly throughout the years.
Apparently, two ages in particular see enormous bursts of molecular changes which are associated with ageing.
Why, and what are the ages?
The Stanford researchers followed 108 people between the ages of 25 and 75, tracking more than 135,000 molecules and microbes over years.
Writing for Stanford’s site, study author and professor of genetics Dr Michael Snyder said: “We’re not just changing gradually over time; there are some really dramatic changes. It turns out the mid-40s is a time of dramatic change, as is the early 60s. And that’s true no matter what class of molecules you look at.”
A massive 81% of participants saw sudden shifts at certain years, rather than gradual changes. More specifically, molecular changes associated with ageing sped up at approximately 44 and 60 years old.
The changes in our mid-forties seem to affect our cardiovascular health; those seen when we hit 60 may impair our immune system too.
And if you reckon your ability to process alcohol, coffee, and fat has gotten worse since 44, this paper says that’s likely down to metabolic changes that occur at that age.
Those in their 60s may struggle more with carbs and face increased skin, muscle, and kidney risks.
Is there a gender divide?
Interestingly, scientists found that menopause was not the great divider they’d expected in these age groups.
Men seemed to experience the same cluster of changes in their mid-forties as women.
Writing for Stanford’s site, Dr Xiaotao Shen, the study’s lead author, said: “This suggests that while menopause or perimenopause may contribute to the changes observed in women in their mid-40s, there are likely other, more significant factors influencing these changes in both men and women.”
“Identifying and studying these factors should be a priority for future research,” he added.
It’s also worth noting that scientists don’t know how much these clusters are down to lifestyle choices, and how much comes from predestined molecular changes.
So, as Dr Synder says: “I’m a big believer that we should try to adjust our lifestyles while we’re still healthy.”