For the last 15 years, Pete Gaffney and the team at PGPT have been among London's best personal trainers helping high-achieving professionals look and feel fitter without wasting their time, energy, or resources.

They have kept royals, politicians, and chief executives of FTSE-listed and Fortune 500 businesses in peak physical condition by completing their programme.

It has given them the energy to lead their high-pressure lifestyles effortlessly.

The team has 65 years of combined experience gained from over 60,000 hours of personal training, having delivered more than 1,350 total body transformations.

According to the Institute of Personal Trainers, Pete Gaffney is one of the world's leading online personal trainers, so we asked him: why does it get harder for men to lose weight when they reach 40?

He explained that when men reach the age of around 40, they begin to undergo a host of metabolic and hormonal changes that need to be accounted for to lose weight effectively.

The fad and crash diets that may have worked in the  past will likely no longer be as effective, as your lifestyle has now changed, and sustainability in your habits has become vital to your success.

At 40, it's time to look at far more than just diet, as the five points below explain:

The 5 quick rules of weight loss at 40

1. Poor Sleep can Beat a Good Diet

Common thought would say exercise and diet are the first port of call for weight loss, no matter our age. Well, it's essential, but not where we should begin…

It's time to ensure you get six-to-seven hours of sleep every night. Missing sleep destroys the hormonal environment your body needs to lose weight. Sleep is foundational!

You are in a fight against changing hormones now. We want to ensure muscle growth or retention while we lose weight, which requires adequate growth hormone.

A study from the University of Chicago showed that men trying to lose weight with inadequate sleep ended up experiencing muscle loss with little to no fat loss. This is not what we're looking for!

2. Our 'WHY' Becomes Vital to Stay On Track

The older we get, the more challenging change becomes, but changing habits is now vital. So we need to get our mindset right.

Motivation is the most powerful tool in our arsenal. So it's time to figure out your 'WHY'; the profound emotional reason you want to achieve this.

It is your 'WHY' that will keep you on track when things get challenging, or you are feeling weak.

A good tip is to write it down; constantly remind yourself by sticking it to a mirror, or on the background of your phone.

3. Don't Go Hungry; It's Not Sustainable

Once we have our hormones balanced, our diet accounts for 80% of our weight loss results.

An effective meal plan does not mean cutting out all carbs and going to bed hungry… Crash diets that we don't sustain can do more harm than good.

Getting on to a sustainable eating plan that includes habits and rules you can stick to forever is essential.

We typically introduce some simple do's and don'ts and adopt an 80:20 approach that accounts for real-life events.

4. Daily Activity is as Important as Exercise

At PGPT, we talk about 'NEAT' (Non-Exercise Activity Thermogenesis). This is our daily activity that burns energy out with exercise.

A common issue we find with the men we work with is that they live a sedentary lifestyle; a lot of sitting down: whether that's behind a desk, in the car, or at the end of a long hard day flaked out on the couch.

So it's important to start 30-45 minutes of daily activity — NOT exercise. Your body must hit its 'Daily Required Movement Threshold' to properly regular your hunger levels.

So take the stairs, not the lift; walk around the office when on the phone; stand up and cook… You get the picture.

5. Time to Begin a Formal Exercise Programme

Once these first four steps are in place, you can begin a formal exercise programme, ideally designed for your condition and requirements.

The most effective exercise options are high-intensity intervals and strength training combined into a time-efficient routine. Life is busy, so it's essential to be efficient and effective.

You invested in your career, now invest in your life.

Get in touch with PGPT, mobile and online personal training for CEOs, senior executives and professionals in London and worldwide.