This is the first in a series of eight posts detailing concepts and attitudes for sustainable personal change. As one would expect of someone maintaining a 155-pound loss for more than 20 years, my examples have to do with food and weight, but their point is to provide concepts and their practical outgrowths to help anyone achieve and maintain healthy change. Today’s concept: “It’s all one thing.”

Over the past 10 years or so, I have involved myself in two discussions professionally: causes and remedies of obesity, and saving the planet from global climate change.

Most people would say they have little to do with each other, and I used to say it as well. Now I see them as profoundly connected, and my case for that is the subject of this post.

First, the obesity thread: I was a fat kid, and obese adolescent by the time I lost more than a hundred pounds the first time. I lost about the same amount, upwards of 130 actually, in my 20s, and still, I approached my 30s rocketing toward 365.

Now, I’ve been in a normal-sized body for more than 20 years. Many things changed for that to happen, but a key difference is that I stopped thinking that my weight problem was “the” problem. Being that heavy was clearly a problem that I would have to overcome if I wanted to avoid the health issues that would likely ensue, but obesity was still only a subset of the problem.

Once I got that, my life began to alter so dramatically, well beyond mere body size, that I eventually gave in to suggestions, two in particular, that I write a book about my experiences, a process that took five years from first keystroke to release party.

During that time, my wife and I moved into a house and substantially remodeled it. My employer, the Boston Globe, put me in charge of a section, but later downsized the section into oblivion and reassigned me to night work. I accepted a buyout from my employer. And we welcomed an adopted baby into our family.

The idea was that the baby would arrive soon after the buyout, so I was going to take a couple months off and then become a stay-at-home dad. But Joseph took years longer than expected to arrive, which leads to the climate-change thread of this yarn.

When it became clear I’d need to find something else to occupy my time — something I could jettison on as little as a week’s notice, once the baby arrived — I settled on advocating against climate change, not only through activism but by writing stories and blog posts that would highlight “green” people and projects.

Calling it “green” wasn’t very specific, but the topic needed some kind of shorthand. Others referred to it as the sustainability movement, so sometimes, so did I. But it took me quite a while to see that that was selling sustainability appallingly short.

Green-building techniques, energy efficiency, and many other disciplines are important changes the world needs to adopt if we are to escape the worst effects of climate change, but they are only a subset of sustainability.

This is where the two threads merged, for me: In both arenas, I had focused on an outcome and considered that the problem. Even if the outcomes are bad, both likely to lead to premature death — of a person, or the planet — they are indications of the problem, rather than the problem itself.

I had already learned this about my obesity: When I tried to solve the problem by losing weight, I had lost weight, dramatically and more than a few times. But the problem — which included self-centeredness, low self-esteem, and inadequate connection to others and the natural world — had always remained, even while the weight remained off, however temporarily.

I had learned it, but not sufficiently to recognize it in a form that could apply to other parts of my experience, or relate it to the experience of others. I now contend the better way to express my condition was that it was unsustainable: That is, I could not continue in the same fashion without contributing to my ruin.

That definition easily scales to planet-level: If we continue doing it this way, will it contribute to our health or degrade it? Modern life is full of such questions that, so far, we’ve chosen to ignore. It is a wonder of ingenuity that we can traverse the globe in hours, not months, but only via a process that contributes strongly to climate change. We have engineered a system of agriculture that spews its waste everywhere: animal excrement concentrated in vast Midwest feedlots; aquatic dead zones that result from pesticide and fertilizer runoff; the outright reliance on fossil fuels via several avenues.

Obesity is an excellent illustration of how planetary and personal sustainability are very often the same thing. Most obesity arises from processed foods — do you know a lot of people who eat mostly whole foods who are terribly overweight? — which are a prime product of industrial agriculture. Deciding to eat more healthfully has not only contributed to my personal health but also to the planet’s.

Rarely does choosing to be more personally healthful require choices that would injure the planet, but it’s true that the overlap of individual and collective sustainability might not be as intense for other personal challenges: wanting to sustain better study habits, or to procrastinate less, or to overcome shyness, as examples.

But this fact — that one standard can reliably point us in the right direction, no matter the details — shows that it’s all one thing.