You're overweight and unfit, so you embark on diet of lettuce leaves and skim milk, and start running like a rabbit in the mornings.

Wrong strategy, says Deakin University clinical nutritionist Professor Madeleine Ball. You'll probably experience considerable pain for little gain.

"Some people have picked up an extreme message on diet and exercise," says Professor Ball, who is investigating the links between diet, lifestyle and disease. "They want quick fixes."

Professor Ball is no advocate of radical diets or get-fit-quick exercise programs. Few people persist with such a radical regimen; they might lose a little weight - unfortunately mainly as water, not fat. In the process, they trigger a metabolic "starvation response" that causes the body to store fat, rather than burn it as energy, so they may end up gaining gain weight in the long run.

Moderation and motivation are the keys, according to Professor Ball. Modest changes in diet and lifestyle can yield long-term health benefits, including permanent weight loss.

Professor Ball and her research students are studying the role of nutrition and exercise in preventing and managing the major killers in the general population: cardiovascular disease, hypertension (high blood pressure) and cancer.

They are also investigating how nutrition interacts with genetic factors in people who have been unlucky enough to inherit genes that put them at risk from these diseases much earlier in life than normal. Individuals with an inherited form of hypercholesterolaemia, which causes very high blood cholesterol levels, may be at risk of heart attacks as early as their 30s.

In some places where she has worked, Professor Ball run special clinics for people with hypercholesterolaemia, and was involved in some of the early studies of some of the drugs that are now widely used to reduce high cholesterol.

"Medical practitioners now prescribe a range of drugs to reduced cholesterol levels. Previous research in which she was involved showed that modifying the patient's diet provides additional benefits for people taking these drugs.

But the drugs do little except lower serum cholesterol levels, so if people make no other changes in their diet or lifestyle, they will not gain the additional benefits of losing weight, becoming more active and increasing their intake of antioxidants like vitamins C and A.

"We want to explore the most effective combinations of diet and lifestyle changes, together with drugs, if they are necessary" says Professor Ball.

"We're interested in various aspects of diet and lifestyle because moderate changes that produce small improvements in a range of health parameters can add up to a significant overall benefit.

"For example, if, in losing weight, you also lower your blood pressure and your levels of levels of blood-clotting factors like fibrinogen and factor 7, you reduce your risk of heart attack and stroke. "

The emphasis is on "moderate", says Professor Ball, because most people find it difficult to comply with radical changes. It's important for family doctors be able to offer their patients different combinations of drugs, diet and lifestyle changes that consider long-established habits, cultural differences - and motivation.

Professor Ball says arguments over the relative merits of low fat/high carbohydrate or modified-fat diets may unproductive.

"Rather than argue over the details of what such diets might achieve, and why one is better than another, we should be saying, 'Great, we have two dietary patterns that may both offer benefits, and someone who finds one diet dreadful may find it much easier to comply with the other.'

"Our interest has broadened from a subject like the role of fat in the diet, to the effects of different types of fat, to phytoestrogens, fibre, and antioxidant intake.

"Someone might find it easy to increase their fruit and vegetable intake, whereas someone else will find it difficult. We want to empower people to find something that will be positively better for their health, without making it too difficult - that way, they can move forward.

"That way, they are more likely to adopt a lifestyle with positive benefits - not because their doctor told them so, but because they find their diet enjoyable enough, and they're getting more exercise in acceptable ways."

Professor Ball's research team is investigating the effects of different types of fat - polyunsaturated FAT, and different forms of mono-unsaturated fats, AND omega-3 and omega-6 fatty acids - on health indicators such as levels of serum lipids, glucose, and insulin.

In a joint project with Professor Paul Nestel at the Baker Institute, they have also investigated the effects of these different forms of fat on the flexibility of the carotid artery (arteries clogged by cholesterol deposits lose flexibility).

"We compared two diets, one low fat/high cholesterol, the other a modified-fat diet, high in mono-unsaturates," she said. "There didn't appear to be any difference in artery flexibility, but there were other differences."

The Deakin researchers are now studying the benefits of including the traditional Asian food tofu (soybean curd) in the diet. Tofu is high in phytoestrogens, which have a similar effect in the body to naturally occurring estrogens.

Phytoestrogens, by counteracting the effects of dihydrotestosterone (DHT), the most active form of testosterone in males, is may provide protection against prostate cancer and cardiovascular disease.

"A man's hormone profile influences his risk of developing prostate disease. Caucasian males are at higher risk than Asian males of developing an enlarged prostate as they age, and a risk of developing prostate cancer.

Professor Ball says that introducing phytoestrogens into the diet could modify the metabolic pathways involved not just in prostate disease, but cardiovascular disease - one dietary change could thus reduce the risk of two common causes of morbidity and mortality in men.

"We became interested in prostate cancer partly because of our interest in sex hormones as risk factors in heart disease and obesity, but then the question arose as to whether dietary factors might also influence the risk of prostate cancer.