I weighed 325 pounds at my heaviest. I lost almost half my weight by cutting down portions and moving more.

Stephen McKenna, pictured with his son, also named Stephen, before and after his weight loss.

This as-told-to essay is based on a conversation with Stephen McKenna, 66, of Boston. It has been edited for length and clarity.

In 2019, at 5ft 8in tall and 325 pounds, I was diagnosed with pre-diabetes and fatty liver, and my blood pressure was out of control.

My doctor, who had advised me to lose weight for years, said I had reached the point when I might consider lap band surgery.

“Wait a minute,” I thought. It was a lightning bolt moment. I didn’t want to have such a serious surgery, but if I didn’t turn things around, they wouldn’t end well.

I knew what I had to do — simply eat less and exercise more. I’d been trying and failing to stick to a regimen since the 1990s, but this time, I had to succeed.

I’d always loved food. Sports weren’t my thing as a kid. And, as I got older, I got bigger. I couldn’t walk down the street on a cold day without sweating.

These uncomfortable feelings motivated me to lose weight. I monitored calories under the supervision of a weight management center. They taught me about the kinds of healthy foods I should include in my diet, and I paid attention to them, but I didn’t exercise.

I ate what I liked — but in moderation

Nevertheless, I lost weight and felt in better shape. People started to compliment me. Instead of spurring me on, the compliments gave me permission to forget what I was doing and go back to my old ways. “Oh, I look really good,” I’d say to myself, “I can do whatever I want again.”

I’d start ballooning back up. I’d regularly go to an Italian restaurant twice a week and have my favorite dish, lasagna. It was large enough to divide into three different servings, but I’d eat the whole thing plus the bread that came with it.

My other passion was desserts. A nearby bakery sold beautiful cannolis, eclairs, and Italian cookies. I’d eat anything with a nice custard filling.

My weight yo-yoed — until that scary wake-up call five years ago. I knew I still needed to be able to eat what I liked but in moderation. So I drastically cut portions — eating one-and-a-half ounces of pasta at a time, not the usual eight ounces, for example — and ate plenty of interesting salads and vegetables, often pickled or roasted with olive oil. I reduced my sodium intake to avoid water retention.

I take at least 7,000 steps every day

Meanwhile, I logged my calorie intake on the MyFitnessPal app, which also tracked exercise. My son, also called Stephen, encouraged me to go outside and walk. He kept it realistic for a guy who was very overweight and didn’t like or want to exercise.

I started with 10 minutes a day and added an extra five minutes each week. The increase was incremental. I now do a minimum of 7,000 steps daily.

It really made a difference. I dropped 30 pounds, then 50 pounds, then 100 pounds. The ups and downs were a thing of the past. Blood tests showed I’d reversed my pre-diabetes, and my blood pressure was good. I am no longer being monitored for fatty liver.

I reached my goal weight of 185 pounds last year. I finally stuck to my guns and felt like an entirely different person.