Apart from meaning he was about as cuddly as a cardboard box, he pointed out that tucking into a sliver of cheese and a glass of wine on a date was a rare "cheat" night for him.

Wild rebellion aside, every other day of his regimented life included a couple of workouts along with tightly portion- and macronutrient-controlled meals, consisting mainly of a bit of grilled chicken or fish with some steamed greens and steamed sweet potato. Throw in an olive if he was being crayyzee. Hold the salt. Hold the oil. Hold the spontaneity and flavour of life.

I admired his discipline and knew instantly we were utterly incompatible.

Becoming a freak of nature is hard work. So, for many mere mortals is losing the final five kilos.

Google it and you'll get about 650,000 results. Like that wasn't enough to convince you of the enormity of this "stubborn" problem on a world scale, Michelle Bridges has written a book about it.

"It takes a fair bit of nous, determination, willpower and discipline to push out that last little hurdle, to get those last few kilos off. You've really got to want to do it," Bridges said.

In a recent blog on the subject, the boys from Precision Nutrition explore the trade-off between lifestyle and being super lean.

So what does it cost?

"The process that helps you lose 'the first 10 pounds' isn't the same one that'll help you lose 'the last 10 pounds'," dietitian and strength coaches Ryan Andrews and Brian St Pierre admit. "Indeed, it usually takes a lot more work as you get leaner."

A healthy body fat percentage is between 10 and 15 per cent for men and 18 and 25 per cent for women.

Most of us are not in this range.

In the US, the average man is about 28 per cent fat, and the average woman is 40 per cent fat. There are no statistics for average fat percentage in Australia, but as the third fattest country in the developed world, we are hot on their sedentary heels.

Stepping from overweight into a healthier weight and body

Starting the process towards the healthier range is not too hard.

It involves simple steps such as cutting down on alcohol or sugary drinks, swapping your apple juice for an apple, not overeating sweets or fast foods (but not necessarily cutting them out entirely) and going for a daily walk.

"If you make a few small changes like these, and do them consistently, in six months to a year, your body fat percentage will drop and fall into a much healthier range," the Precision Nutrition coaches advise.

Stepping into a healthy weight and body

This is when we need to step it up a gear.

It involves upping the intensity of exercise, including 30 minutes of moderate intensity, five days a week or 75 minutes of high intensity scattered across the week, doubling these numbers for additional benefits.

As well as this, it involves consciously eating more vegetables and whole foods, learning to eat only when we're hungry and stop when we're comfortable (not full) about three-quarters of the time, prioritise sleep and consume less junk (three to five times a week max) and booze.

"Many folks will decide that these changes are worth making. They want to look and feel better, get a good night's sleep, get off medications, and so forth. So they're ready to compromise," the coaches say.

"Other folks will decide that they're not yet ready to make more adjustments. And that's fine too.

"The most important thing is that you realise: In order to change … you have to change."

Stepping into super-lean

The trade-off starts to become significant here for most people. Of course genetics play a part - one "cut" male friend of mine exercises like a freak but lives off Maggi noodles and Ben and Jerry's.

Despite being lean, taking advantage of his metabolism by eating rubbish means he risks the dangers of skinny fat and could set himself up for health problems down the track.

For the rest of us, dedication to staying super-lean can start to eat into socialising time; it requires planning and certain sacrifices.

You'll need to exercise and break a sweat for 60 to 75 minutes a day, five days a week, eat only until you're comfortable 95 per cent of the time, limit carbs to post workouts and limit fast-food and booze to once a week.

Getting into the territory of my fitness model friend ups the ante even more and requires complete dedication/fanaticism to fitness, allowing minimal room for error.

"This process is not for the faint of heart," Andrews and St Pierre say.

"It goes against biological cues. It requires exercising when exhausted. It demands ignoring their desire for food in the face of powerful hunger cues. It involves intense focus and dedication."

This level of dedication does not necessarily mark good health. In fact, the pursuit of being super lean can tip people over the edge of health into obsessive, dangerous territory.

"Having a six-pack doesn't automatically make you healthy. In fact, getting too clean can be actively unhealthy," Andrews and St Pierre say.

"You might end up with amenorrhea, low libido, disordered eating, bones like Swiss cheese, social isolation, and a host of other problems."

A little trade-off for health and happiness is worth it, but if you ever find yourself looking longingly at the fitness model on the cover of a magazine, it's worth weighing up the costs to your health (and happiness).