About four years ago, a man in his early 20s who had boxed a bit in his teens asked me to recommend a diet that would allow him to shed body fat and add muscle. I explained to him that such a diet truly does not exist because the catabolic and anabolic states cannot occur simultaneously.

Catabolic? Anabolic?

The boxer looked at me as if he had just staggered to his feet and I was wearing a bowtie and counting to 10.

“‘Catabolic’ just means breaking down,” I said. “‘Anabolic’ means building up. When you’re in a catabolic state, you’re breaking down and losing overall mass, both fat and muscle.

“When you’re in an anabolic state, you’re building up or at least maintaining overall mass. It’s why we use ‘anabolic’ to describe steroids.”

While I acknowledged that a few genetically blessed individuals can actually add muscle while losing fat, I explained that most personal trainers will play it safe. They will first create a diet for a client that causes him to lean out and then create another that causes him to bulk up.

A clearly overweight client, for instance, would be advised to focus on aerobic exercise and follow a weight-loss diet until he reduced his body weight to a healthy level. Inevitably, some muscle mass will be lost along with body fat, so the next phase would emphasize weightlifting and a muscle-building diet designed to not only recoup the lost muscle but to add even more.

After a year, the man might only weigh five pounds less, but if that’s because he first lost 20 pounds of fat and then added 15 pounds of muscle, all but the legally blind would notice and many who did notice would be envious. Except the former boxer wasn’t really overweight; in fact, by adding just five pounds of muscle and losing five pounds of fat, he would look as good as any professional middleweight.

To help that happen, I suggested he read up about what many call nutrient partitioning.

It’s not hard to follow, I explained. All it requires is knowledge of the macronutrients and a reworking of the amount of each that you consume so that your body is more likely to build muscle than store fat.

Macronutrients?

Again, he looked as if he had taken a 10-second snooze in a boxing ring. “The macronutrients,” I repeated. “You know, proteins, fats, carbohydrates.”

Either he did or he learned about them because when I saw him a few weeks later, he looked a lot leaner and a bit more muscular. I told him so. He smiled as if he’d just won a bout by TKO and said, “It’s all because of Macros.”

Now I was the one who felt punch drunk. Could Macros be the name of a foreign-born and very effective personal trainer new to the area?

Not even close.

If I wasn’t such a social media hater, I would’ve known that there’s no need to capitalize, that macros is short for macronutrients, the word people use when they post information on Instagram or Facebook or Twitter about what’s become known as the Macro Diet or Flexible Dieting. It’s what the former boxer found on his smart phone while surfing for info about nutrient partitioning.

Which makes sense because the two theories are so closely aligned.

But oh, what irony.

Social media, smart phones, and the apps available for them (Environmental Nutrition suggests using MyFitnessPal, MyMacros+, or IIFYM in their July 2018 article about the Macro Diet) have made dieters willingly do something that they were loathe to do when the job required pencil, paper, a dietary scale, and a calculator.

Count calories.

From the first time I taught a course on personal nutrition, I said something that I’ve detailed dozens of times in print since then and is still true today: Weighing the foods you eat is the only way to really know how many calories you are consuming. (Most people are really poor at eyeballing foods and estimating amounts.)

Knowing how many calories you are consuming is the only way to ensure weight loss.

And I have had dozens of students lose weight doing just that — and far more not even try because they see the process as too much of a hassle. But the use of smart phones and apps lessens the hassle, and social media makes it trendy instead of nerdy to count calories, so the diet — four years after I crawled out from under my rock and encountered it — is still in vogue.

And since the diet concept is flexible enough to be used by both the desperate dieter and the dedicated athlete, next week’s column will focus upon its positives features.

As well as how some people misuse it as a way to eat junk.