In my personal and professional experience, I have noticed that both the effects of higher quality diet on a neglected body and of low quality diet on a healthy body, are relatively slow to show.
In many ways it’s down to cellular life span.
Your body is building new cells all the time. And it’s also repairing damaged cells and killing off old cells all the time. It’s making energy and fighting illness. Building materials? The food you eat. Repairing materials? The food you eat. The efficiency of energy production processes, immune response, brain function? The food you eat. The quality of the cells that your body manufactures, its ability to repair the cells that wear out, it’s accuracy at recognising and killing off faulty cells (cancer) are directly dependent on the quality of the food you consume.
So far so good.
Cells don’t live forever. But they do live for a long time. If they’re badly made, they’ll still limp on (unless your body is healthy enough to recognise and repair/replace them). Some cells live longer, some cells live shorter lives. But all in all, it takes about 7 years for all the cells in our body to renew.
Now, some of those cells of yours were built out of high quality food, some out of low quality food. And they will hang around in your body for, on average, 3-7 years.
So, the more high quality meals vs low quality meals you have, the more high quality cells you are building for the next 7 years of your life. And vice versa.
That’s why, after eating better for only 2 months you will be feeling MARGINALLY better, but wont be feeling as good as somebody who had been doing that for 3 years. By the same token, if you’ve been feeding your body well for years and then went on 2 months of less than good quality food, you will feel MARGINALLY worse, but won’t be feeling as crappy as somebody who has been eating poorly for years.
It’s not a ‘bad diet vs good diet’ thing either. If your diet this year is a little better than last year, you’re building a generation of cells that are a little higher quality than the previous generation.
Aging and genetics does affect your cell quality, but your can’t control that. The only thing you can control is the food you eat and your lifestyle. It’s all about either doing the best with what you’ve got or squandering whatever you’ve got. That’s why you can have 70 year olds who, despite being dealt a worse genetic card, take care of themselves and end up looking and performing better than some 30 year olds who were dealt a healthy body but destroyed it.