Pounding away on the treadmill at the gym and nibbling on lettuce leaves is not the secret to feeling fab for summer. According to nutrition specialist Dr Libby Weaver, it's a lot deeper - and a lot more rewarding.

I used to run furiously every day and I've always had a fantastic diet," explains holistic nutrition specialist Dr Libby Weaver. "But when my lifestyle changed and I started setting up retreats in Australia, there was no time to run. Instead I taught t'ai chi classes and took clients walking and the weight just started to fall off me.

"I couldn't work it out so, being the science geek that I am, I asked 'what else is going on?"'

The Australian-born Weaver, who has a PhD in biochemistry, began to explore the power of stress hormones and what encourages women - and men - to store body fat. "It is so much more than just calories and exercise."

Burn fat not sugar

"It is our nervous system that makes the decision whether we are going to burn fat or sugar," explains Weaver. "Within that there is the sympathetic nervous system, which is designed for the primal 'flight or fight' response. The other part is the parasympathetic nervous system, which is all about rest and repair.

"Most women spend a lot of time in what I call 'sympathetic dominance'; we may know we are safe, but because we have a to-do list that's pages long, we're juggling work, families ... there is the perception of pressure to your body that is similar to being chased by a tiger. This 'stress' means your body is burning sugar because this is what will fuel your escape, and you're not burning fat which is what most of us want to do."

Weaver, who now lives in Auckland and whose Newmarket practice is booked out until the middle of next year, doesn't deny food is part of our weight problem, but for most women she says, it all comes down to chemistry - particularly that which is driven by hormonal factors and, all importantly, our thoughts.

Be kind to yourself

"A lot of us present a calm face to the outside world but don't realise how worked up we are on the inside - like a mouse on a treadmill that's spinning very quickly," she laughs.

"So many women are trying to please everybody and make everyone happy. The key here is, that you can do this from a place of calm or a place of panic - hence the burning sugar instead of fat. But how great is that, if we can turn our lives to coming from a place of peace and the byproduct is a healthy body and mind?

"I meet a lot of women who do all the right things but their weight won't shift, so that's when concentrating on the psychology is just as important as much as their estrogen, progesterone, cortisol, insulin and hormones.

"We have to be realistic, we can't all live in a zen-like space but it's about self-awareness and accessing that space. I think for many New Zealand women it's about being kinder to themselves and bringing more rituals into their lives. We have to schedule them in."

Love your liver and your adrenals

By being kinder to ourselves it means being kinder to our adrenal glands, which are responsible for our stress hormones, our sleep hormones and drive our immune functions.

From an energy perspective, says Weaver, they are vital. "If you have a tendency to having flat moods it will be because your adrenals need support. Likewise, if you're low on energy it could be that your liver is congested. Often you will have a roll of fat just under your bra which can come and go, this is a sign your liver needs some love. Likewise, cellulite is an indication of what's happening with your liver and lymphatic system."

A liver person, says Weaver, is someone who is tired, full stop, while with the adrenals you can be tired but also wired.

"These people might come across as calm but when you delve a little deeper chances are they've been through some tough times or big change. Classic signs of functioning under stress or pressure, is using caffeine in the morning to get you going and then wine in the evening to unwind."

Liver "loaders" are alcohol, caffeine, refined sugars, deep-fried foods and synthetic substances. "We have to be mindful of what we put on our skin, "says Weaver. "As products can be absorbed through the skin directly to the blood."

Weaver encourages clients to eat plenty of fresh food, especially fruit and vegetables, to avoid processed food where possible and not too much alcohol. "If you actually cut out caffeine, you'll be amazed at how much more energy you have. But if you have to have it, that's okay. It's not about depriving yourself of the things you love, but most people know if they eat that chocolate, overeat, or drink too much wine, the consequence is they are going to feel lousy. So just don't do it every day. What I try to teach people is that it's what you do every day that impacts on your health, not what you do sometimes."

Check your estrogen and progesterone levels

There are many key patterns in women's biology and, says Weaver, for menstruating women estrogen plays a big part. For half our monthly cycle, estrogen is dominant laying the lining of the uterus in preparation for pregnancy (whether that's what's on your agenda or not).

"Because it wants our body to be prepared - a form of survival - it wants us to have a decent amount of fat. If your body is creating too much estrogen, then a sluggish liver won't be able to process it and it will be stored up, along with fat."

Meanwhile, progesterone, which is made from the adrenal glands, is working to hold the lining in place. Biologically it's a powerful anti-depression, anti-anxiety, anti-ageing mechanism as well as being a diuretic, so helps get rid of excess fluid. It's very important in fat metabolism. If your adrenals are under pressure, progesterone will drop."

This can all lead to PMT which, recent statistics have shown, affects 90 per cent of women in the Western world.

Explore your emotions

"While our biochemistry is the same, our psychology is very personal. We are governed by how we feel," says Weaver. "If you can change your perception of how you see life - see it as an adventure rather than a struggle - how does that change the way you run it? People eat in an unresourceful way when they are touching on emotions that are really uncomfortable for them to feel, but they are subconscious feelings so they don't realise they are doing it. The key is to tap into what you really want at that moment, it's not often the food, it's the feeling."

Nourish your soul

"I don't believe in living a puritanical life - drinking bubbles with a friend or having a treat of chocolate cake nourishes the soul, which is an imperative form of nourishment. But asking what role food plays in your life can be a key clue to your eating habits. If food, coffee and alcohol is a pleasure for you, then maybe you need to think about what other things in your life bring you pleasure and then you can turn to those more. Ask yourself what else you love. Is it reading, gardening, going to the movies, dancing ...

"I had one client, she overate every night after dinner and she knew she wasn't hungry. I got her to identify what she wanted to feel at that time. She had two little children, didn't have a partner and she was missing feeling loved ... I said 'do you ever go and stand in the doorway and watch your children sleep?' And that works for her, she's stopped overeating. It's that kind of stuff. We race through our days and we miss the precious stuff."

Weaver, who holds regular workshops and seminars around the country, is about to launch her first book, Accidentally Overweight, next month. Its title, she says, is based on the reality that no one sets out to be overweight. "So many people have been raised to think that as long as you exercise harder or eat less, then you will lose weight. For some that happens, but it is not a pleasurable way to live. And it can actually be an unhealthy way to live - thinking you have to push yourself more and more or live on lettuce. This is not healthy for the mind or body. I want to show that calories are just one piece of the puzzle. Of course, you can't eat like a piglet and expect it to all fall into place, but you also shouldn't have to starve yourself."

Respect yourself

"In any given moment in an adult human body, there are an estimated 10 trillion cells with the potential to communicate with one of the 76 organs," enthuses Weaver. "Your body is extraordinary and you will get the best out of it by cracking its fat-burning, energy-producing code. Making small changes on a daily basis can have huge results and allow you to live that healthy, vital life you want."

* For more information, see drlibby.co.nz.

To pre-order a copy of Dr Libby's new book Accidentally Overweight (on sale next month), go to accidentallyoverweight.com for a special Viva discount.