If you've tried the motivation tricks and still can't shed kilos, it may be time to get help from the big guns. Here, who they are and what they can do.

Weight-loss coach

She tackles fat with positive talk and develops personalised weight-loss programs based on lifestyle and behaviourial changes. But be warned: anyone could call themselves this.

TRY HER IF You need a kick to put down the chips and get moving.

WHAT SHE'LL DO Ask you to keep a log to pinpoint the emotions triggering you to overeat or be lazy, then teach you to counter negative thoughts.

TOP TIP "Pre-plan your meals so you can pre-plan your shopping and always have cupboards stocked with food and drinks that support your weight loss," says Jamie Hayes, managing director of Healthy Inspirations weight-loss centres for women.

COST Varies from $30 per week to $200 an hour.

FIND HER See au.local.yahoo.com and type in weight-loss coach.

Accredited practising dietitian

A university-qualified pro who can provide expert and up-to-date nutrition and dietary advice.

TRY HER IF You're confused about what kind of eating plan to follow. Or if you've hit a plateau.

WHAT SHE'LL DO Analyse everything you put in your mouth so she can find out what, when, where and why you're eating. Then she'll create a meal plan.

TOP TIP "Keep a food diary," says dietitian Dr Clare Collins. "You'll realise either how much you're eating or you'll discover how many kilojoules are in each food. Either way, if you're honest, a food diary is an excellent way to educate yourself and see where you're tripping up."

COST About $70 to $100 for the initial consultation, then approx. $40 to $60 for every session after.

FIND HER Go to daa.asn.au

Nutritionist

In theory, anyone can call themselves a nutritionist as there are no rules governing the use of the term, but an "Accredited Nutritionist" is a tertiary-qualified nutrition professional who has expertise in a range of nutrition services. To make sure you're getting the right advice, always ask about qualifications and credentials.

TRY HER IF You suspect there's an underlying reason why you can't lose weight. "Any contributing factors to weight gain such as underactive thyroid and hormonal imbalances such as polycystic ovarian syndrome or high insulin levels can be corrected," says LeVity Health nutritionist Sarah Luck.

WHAT SHE'LL DO Take your health history, combined with tests to identify nutritional deficiencies, areas of toxicity and cellular health.

TOP TIP "Skipping breakfast is disastrous for your waistline," says Luck. "Eating a good quality breakfast sets you up for the day, and you're more likely to make healthy choices for the rest of the day."

COST About $80 to $150 per session. Health fund rebates are available.

FIND HER Go to naturaltherapypages.com.au

Weight-loss psychologist

Someone with a PhD in clinical psychology who specialises in eating disorders and weight control.

TRY HER IF "You know what you're supposed to do to lose weight but just can't make yourself do it," says Dr Ed Abramson, a professor of psychology.

WHAT SHE'LL DO Ask you to talk to find out whether you overeat because of boredom anger, stress...

TOP TIP "Even mild physical activity will lift your mood and give you energy to do more," says Dr Abramson.

COST About $150 per 50-minute sesh (might be covered by health fund).

FIND HER Ask your GP for a referral or go to psychology.org.au