Your Health Is More in Your Control Than You Think.
We tend to think of ageing as something that happens to us later. A problem for our sixties and seventies. Something to deal with when it finally arrives.
The science says otherwise.
How you feel at 70 is shaped, to a surprising degree, by the choices you are making in your twenties and thirties. Not all of it. Genes matter. Luck matters. But a large share of it is being decided right now, in the background, by how you eat, how you move, and whether you actually know what is going on inside your body.
This article is about that last part. Because the single most useful thing you can do for your future health is not a supplement or a diet. It is information. And it is far easier to get than most people realise.
Ageing starts earlier than you think
Here is something that surprises most people. The decline does not begin in old age. It begins in your thirties.
After the age of 30, most people lose roughly 3 to 8% of their muscle mass per decade, and the loss speeds up later in life. Bone density tells a similar story. You reach your peak bone mass in your late twenties, and from then on it is a slow drift downwards. Visceral fat, the fat that sits deep around your organs, tends to accumulate across the same years.
None of this is dramatic in the moment. You do not feel a percentage of muscle leaving. You do not notice a slow change in bone. That is exactly why it matters. The slope you are on in your thirties is the slope you carry into your seventies. A small difference in direction now becomes a very large difference in outcome later.
The good news is that almost all of it responds to action. Muscle can be built at any age. Bone responds to load. Visceral fat responds to diet and movement. But you cannot act on a problem you cannot see.
“But isn’t it mostly genetics?”
This is the question people use to let themselves off the hook.
For years the accepted view was that genes account for roughly a quarter of how long you live, leaving the other three quarters to lifestyle and environment. A major twin study published in Science in January 2026 challenged that, arguing the genetic contribution may be closer to half once you strip out deaths from accidents and infection.
So the debate is live. But here is what both sides agree on. Even the authors who raised the genetic estimate were clear that lifestyle still matters, and that diet, exercise and sleep can add ten years or more to a life. Your genes set a range. How you live decides where inside that range you land. That part is yours.
You cannot change what you cannot see
Most people go through their twenties and thirties flying blind. They feel fine, so they assume all is well. They wait for a symptom to tell them something is wrong.
The problem is that the things that shape your health at 70 rarely announce themselves early. Rising blood sugar, creeping cholesterol, low-grade inflammation, thinning bone, accumulating visceral fat. By the time any of these produces a symptom, it has usually been building for years.
You do not have to wait. You can simply look.
What a blood test actually tells you
A blood test is the fastest window into your body that exists. You give a small sample, and for routine markers the results come back within 24 to 48 hours.
In that one test you can see your cholesterol, your blood sugar control, your vitamin levels, your thyroid, your liver and kidney function, and your inflammation markers. Together they give you a clear snapshot of what is happening inside you right now, and a baseline you can measure everything against in future.
One honest caveat. Not everything is fast. Some specialist tests, certain hormones and allergy panels among them, take three to five working days. But the core picture of your metabolic health is available to you within a couple of days of deciding to look.
What a body scan adds
A blood test cannot tell you everything. It cannot tell you how much muscle you are carrying, how dense your bones are, or where your body is storing fat. For that you need a DEXA scan.
DEXA measures body composition to within one to two percent. In one short appointment it shows your muscle mass, your bone density, and your visceral fat.
That last number is the one worth paying attention to. Visceral fat is the deep fat wrapped around your organs. You cannot see it in the mirror, a set of scales will not catch it, and BMI ignores it entirely. Yet research has found that the amount of visceral fat you carry in your thirties and forties predicts arterial plaque, type 2 diabetes and early death decades later. It is one of the strongest long-term risk signals we have, and it is invisible until you measure it.
A DEXA scan turns the slow, silent changes of ageing into numbers on a page. Are you losing muscle. Is your bone thinning. Are you storing dangerous fat. Once you can see it, you can do something about it.
It does not take long. The hard part is deciding to look.
When you add it up, the whole thing is remarkably quick. A blood draw takes a few minutes. A body scan takes a few minutes. Most results are back within 48 hours.
The barrier was never time. It is the quiet fear of finding something. But that logic runs backwards. The earlier you find something, the more easily you can change it. A number you do not like at 30 is an opportunity. The same number discovered at 60 is a diagnosis.
So where do you start
Get a baseline. A blood test and a body composition scan together will tell you more about your future health than any wearable or supplement. Know your numbers, not just your weight.
Then act on what you find. Lift weights. Eat enough protein. Sleep properly. Build your meals around whole foods. None of this is new, but it is far easier to stay consistent when you can see it working.
Then measure again. That is the whole loop. Look, act, look again.
Your health at 70 is not fixed. It is being written now, one ordinary decision at a time. The first decision is simply to find out where you stand.
If this was useful, share it with someone in their twenties or thirties who thinks they have plenty of time. And if you are not yet subscribed, you can join below for free.