What Is Flexible Dieting?

It’s time to set things straight

“Flexible dieting.”

The term is thrown around a hell of a lot these days, yet 10 years ago, you’d have been forgiven for thinking that flexible dieting meant eating a stick of celery whilst doing the splits.

While the majority of us involved in the health and fitness industry have a good grasp of what flexible dieting is, there are still a number of folk who either don’t understand it, don’t get how it works, or take it to extremes, bastardising the principles that it stands for.

It’s time to set things straight.

We’ll talk through the history of flexible dieting and IIFYM (If It Fits Your Macros,) discuss why and how it works, go into the pros and cons, as well as clearing up a few myths.

Whether you’re a seasoned flexible dieter, or a newbie to this world of pop tarts and macro counting, this article is for you.

Flexible Dieting:

A Definition It’s tough to give flexible dieting a firm definition.

People tend to have differing views and opinions over what exactly is involved, and what you need to do to be classed as a flexible dieter.

This is hardly surprising though – think about the “arch nemesis” of flexible dieting – the ever-present clean eating – and you’ll realise that quite often in the nutrition game, it’s impossible to perfectly define any eating style or concept.

That being said, I think the closest we can get to a definition of flexible dieting is something along these lines:

“A diet that doesn’t impose any restrictions on food sources or choices, and employs a monitoring system that looks at quantitative data – i.e. calories and macronutrients.

The degree and strictness of the monitoring can be altered and changed depending on the individual’s goals, preferences and lifestyle.”

To me, that works pretty well.

Flexible dieting doesn’t ban any foods, and it doesn’t even judge foods or food groups as good or bad. Each individual item can only be viewed in the context of a diet as a whole.

For instance, let’s look at a couple of foods –

Ice cream and broccoli.

Ask someone on the street which is the healthier food, and they’d respond with broccoli.

But what if that broccoli only made up a tiny portion if a person’s diet?

If they were already over-consuming calories and getting fat, and adding the broccoli only took them further into a calorie surplus?

Or the ice cream?

What if having a small bowl of ice cream every few days helped a dieter avoid binging on a whole tub of ice cream once a week?

Or, the dieter had already eaten enough protein one day, got in plenty of vitamins, minerals and fiber, yet had carbs and fats left to eat – would having a bowl of ice cream within their calorie allowance be unhealthy or cause them to gain fat?

Answer = No.

“Hold on, So You’re Telling Me I Should Stop Eating Broccoli and go for Ice Cream Instead?”

If only!


That’s taking a slightly short-sighted view, as, unfortunately, many clean eaters, or those from outside of the industry tend to do.

All we’re saying is that flexible dieting doesn’t demonise any foods, and that you take a view of your diet as a whole before looking at the semantics, and tiny, minute, often insignificant details.

One of the main concepts behind flexible dieting is that you get better results from being less strict.

Ask yourself this – how many times have you tried to diet?

A lot, right?

And why did you fail?

I could be wrong, but I’m guessing it’s because you felt the diet was just too restrictive.

You went for something – whether it was low-carb, clean eating, a fasting diet, Atkins, South Beach, or a shake-based plan – and got sick of having to avoid foods you enjoyed.

At the start of diets like these, your motivation and willpower are high, so you don’t mind giving up your favourite meals, or eating bland, boring, dry foods, as you feel like it’s a sacrifice worth making to achieve the body beautiful.

Pretty soon though, that motivation starts to dwindle. You either consciously decide to break your diet, maybe as a reward, or perhaps because you just can’t be bothered with it, or you go to extremes.

A good example is eating out.

What happens, if, say, you’re following a Paleo diet, and eating virtually nothing but meat, fish, vegetables, fruits, nuts and oils and get asked to go out for a meal with friends?

At home, you’re perfectly happy sticking to your diet guidelines, when you’re in control of cooking and what goes in your cupboards, but your friends want to go out to a burger bar.

All of a sudden, there’s NOTHING on the menu you can eat.

So what do you do?

Not go? Sit there and don’t eat? Order a plain chicken breast and side salad?

Or, do you do what most do, and think –

“Well, if I can’t stick to my diet, I may as well have a blow-out” and indulge in a high-calorie, all-out binge, which results in you feeling guilty, bloated, stuffed and inevitably leads to fat gain.

With flexible dieting, you would be able to go out for that meal and avoid these situations.

If you’re in a strict fat loss phase, you’d find a way of picking a dish that could be worked into your daily calorie or macronutrient allowance, and eat that. Or, if you were just dieting for general health and fat loss, then you might have it as a free meal, where you eat what you fancy, yet due to the unrestrictive nature of your diet, you wouldn’t feel the need to binge, and so would eat until satisfaction, rather than sickness.

Going Back … and Going Forward

People often ask who “invented” flexible dieting, or where the concept came from.

Well, really – it’s science!

Our bodies have always worked in this way, responding to calories and macronutrients, NOT specific foods. And that’s what I’m going to talk about a lot more next time round.

For now though, we’ll end with how flexible dieting hit the mainstream –

The first instance was Lyle McDonald’s book “A Guide to Flexible Dieting” which was published in 2005.

And it reached the realms of bodybuilders and physique athletes via the Bodybuilding.com forums.

A poster would often ask –

“Can I eat X, Y. Z food”

To which a knowledgeable forum member would respond with –

“I.I.F.Y.M – If It Fits Your Macros”

Next time, I’ll be back to talk more about the science, and take you through setting up your own flexible diet so you can eat cookies, cake and chips and get shredded.

Looking for daily tips & motivation?

Follow Nick on Instagram @nickcheadlefitness