The tone in my buddy’s voice told me he was uncomfortable and probably even a bit afraid when he said, “May I ask you something?” The look on my buddy’s face made me fear the worst.

Was he going to ask about brain tumors? Stage-four pancreatic cancer? Early-onset Alzheimer’s?

“I really need to go on a diet . . . again.” After another protracted pause, he explained. “They always work for a while, but then, ‘Katy, bar the door.’ I gain the weight back about twice as fast as I lost it.”

“What’s causing that?” he wanted to know.

I simply said, “The word itself.”

My friend looked confused, so I elaborated. I will now share a version of that with you.

The first definition a dictionary usually lists for “diet” goes something like this: “the foods a person or an animal habitually eats.” The second listed definition addresses how we now usually use the word: “a special restrictive diet employed to lose weight or serve some medical purpose.”

To borrow from the Bard, “Therein lies the rub.”

The mistake my friend, who asked to remain nameless, makes is that he does “definition number two” until he reaches his goal weight, but then reverts back to “definition number one” and the eating habits that caused the weight gain initially. To succeed long-term, he needs to change the foods he habitually eats year-round to eliminate the need to eat a restrictive diet for a portion of it.

A recent study, in fact, verifies that.

Researchers from the University of Florida at Gainesville supervised 75 subjects who attempted to lose weight via a 12-week, internet-based program. The 70 who remained in the program until the end lost an average of 12.7 pounds.

They were then told the study was done, but that’s when the most important part of the study began.

The researchers requested that the 70 weigh themselves daily for the next 36 weeks and made it really easy for them to do so. You would think that such a situation would keep the subjects so aware of their weight that the weight lost would not return.

And that was the case. Initially.

By the 11-week mark, however, all the participants had regained some weight, with the average at about a half pound every month, and that trend continued for the remaining 25 weeks. But regaining the weight lost after ending a diet does not have to be.

Not if you improve the foods you habitually eat.

Kathryn Ross, assistant professor at the University of Florida College of Public Health and Professions who lead the aforementioned study, explained the situation to Medical News Today this way: “There is not a huge difference between the number of calories people are eating when they hit their goal weight [during dieting ] versus what they need to maintain [afterwards].”

Ross concedes, however, it’s rather likely that caloric consumption increases. Because of this, she advises to increase consumption by 100 calories per day and keep checking the scale.

I say this is great in theory but not in practice.

First of all, I have weighed my foods for more than 30 years and believe even when you are intent upon being exact, there’s a margin of error of at least 10 percent — which is 260 calories for me to refuel on a day I do a moderate 60-minute workout. So even if you think you are limiting yourself to Ross’s suggested increase in cals, you may not be.

Second, an increase of 100 calories won’t even register as an increase in your body if you’re eating bad-for-you foods. A single homemade cookie, for example, often contains more than 100 calories.

If you want to treat yourself to a doughnut yet keep to that number, you need to cut a plain, glazed one in half and eat the second piece tomorrow.

But there’s good news lurking behind this gloom.

You can keep the lost weight off if your diet never ends. But when I use the word diet here, I do not mean the aforementioned definition number two — “a special restrictive diet employed to lose weight or serve some medical purpose,” but definition number one.

By the improving upon the foods you habitually eat, a number of good things naturally happen.

Since “better” foods like fruits and vegetables contain more fiber and are mostly water, you satisfy your hunger with fewer calories. Replacing red meats with fish or fowl provided you prepare them properly does the same.

Calorie counting isn’t really needed, according to the research led by Barbara Rolls, PhD, at Penn State that led to the eating strategy called volumetrics. That research determined that we instinctively eat nearly the same amount of food by weight every day.

If you eat calorie-dense junk food, you’ll need to consume far more calories to reach that weight than if you choose healthy foods. “Diet” that way and unwanted weight should dissipate.