Some diets promise weight loss, while others claim to help you live a longer, healthier life. We’ve put the most popular under the microscope: what’s the science behind them and which one will work best for you?







DASH
It stands for Dietary Approaches To Stop Hypertension.
What it is: The salt-restricted diet – developed to counteract high blood pressure – emphasises fruits, vegetables and whole grains, and includes low-fat or non-fat dairy, plus sweets in moderation.
What happens in the body: DASH is heavy on foods with minerals linked to blood pressure regulation, while cutting salt. Reducing sodium optimises blood flow throughout your body, while the antioxidants you munch work to protect you from disease.
Pros: DASH is simple to follow because it uses everyday foods and isn’t overly restrictive. The plan is easily modifiable for weight loss (one study found an average of 1.4kg lost over eight to 24 weeks).
Cons: None, unless you hate to track and count. “This diet has specific nutrition targets and servings, which can be a turnoff for some people,” dietitian Jaclyn London says.
Intermittent Fasting
Eating very few kilojoules for all or part of a day.
What it is: One of the most popular variations of intermittent fasting is the 5:2 plan – you eat normally five days a week, then limit your intake to about 2000kJ (500cal) on the other two days.
What happens in the body: There’s growing scientific evidence to show that fasting can improve your health, from helping with weight loss, to protecting your brain, and even improving diabetes control.
Pros: Fasting focuses on how you eat, rather than what you eat, so it’s less of a ‘diet’ and more of a lifestyle.
Cons: Some feel deprived on fast days and ‘feast’ on the other days, making up any kilojoule deficit. The risks include fatigue and low blood sugar on fasting days, says nutritionist Jaclyn London, and some daily medications need to be taken with food, so diabetics should give it a miss. “Everyone should double-check with their doctor before starting,” she adds.
Keto Diet
A very high-fat, very low-carb diet for weight loss.
What it is: From 70 to 90 per cent of kilojoules come from fat and just 10 per cent or less from carbs. A keto meal might be steak and salad, that’s it. Rice, pasta, bread and starchy vegies (spuds, peas, corn), along with dairy and most fruit (with the exception of ‘allowed’ low-carb fruit like berries) are forbidden. Meat and other high-sat fat foods are abundant.
What happens in the body: This diet puts you into a state of ketosis, where your body burns fat instead of carbs for energy.
Pros: You can drop weight fast, and fans say they aren’t hungry – the pseudo-starvation state triggers hormones that quell hunger cues.
Cons: Much of the initial weight loss is water. “For every gram of carbs not eaten, three grams of water are lost,” says nutritionist Kristine Clark.
The water and electrolyte loss can also raise your risk of dehydration, which contributes to the ‘keto flu’ some get when first starting. “You’ll suffer from headaches, muscle soreness and constipation, and feel moody and fatigued,” she says. You’ll probably need dietary supplements for all the vitamins and minerals you aren’t eating, which adds cost and raises your risk of health problems.
Paleo Diet
You eat as our hunter-gatherer ancestors are thought to have eaten - so only foods found in nature, and nothing packaged, processed or farmed.
What it is: A strict Paleo diet is meat (preferably wild game), fish, eggs, nuts, and wild plants, with no processed food, sugar, salt, dairy, grains, legumes and few starchy vegies. The theory is that most of our modern health woes (cancer, diabetes, heart disease) started when agriculture did.
What happens in the body: Avoiding processed food automatically spares you the blood-sugar roller-coaster from refined carbs and sweets, and eating less sodium may mean lower blood pressure. Consuming only whole foods “can help with weight loss as well as chronic-disease risk,” says nutritionist Jaclyn London.
Pros: The focus on fresh produce scores a lot of points. You can eat as much as you want of permissible foods. Limited studies have confirmed that people can lose weight on Paleo. One found that women lost significant fat mass and waist circumference and lowered their triglyceride levels in six months, although they regained some of the weight later.
Cons: By avoiding whole grains and legumes, you skip vitamins and phytochemicals, potentially raising your risk of heart disease, cancer and diabetes, Jaclyn says, while avoiding dairy leaves out protein and calcium.
Vegan
Followers don't eat any foods from animals, including eggs, dairy or even honey.
What it is: Many vegans choose to eat this way for either animal welfare or environmental reasons.
What happens in the body: By cutting out meat and dairy products, you may eat fewer kilojoules that come from saturated fat, says Jaclyn London. You may also add more fibre-rich foods to your daily meals, which helps your heart and aids digestion.
Pros: When done right (lots of fruits, vegetables, nuts, grains and legumes), a vegan diet tends to be high in vitamins and phytochemicals, and low in saturated fat. This means lower rates of heart disease, some cancers and diabetes.
Cons: Eating a balanced diet as a vegan can require a load of planning to get the nutrients you need – especially vitamins B12 and D and omega-3 fatty acids, Jaclyn says.
Mediterranean Diet
A style of eating in keeping with the traditional diet of villagers living around the mediterranean sea.
What it is: The Mediterranean diet emphasises healthy fats in foods such as nuts, olives and plant-based oils; seafood; legumes such as chickpeas, beans and lentils; fruit and leafy greens; and whole grains. You can even have a daily glass of wine. Modest amounts of dairy are encouraged, but red meat is limited.
What happens in the body: Because it’s heavy on fresh produce, whole grains and healthy fats, you’ll get loads of B vitamins for energy, plus disease-fighting antioxidants, Jaclyn says. Many of
the foods you’ll fill up on are linked to improved heart health and reduced risk of chronic disease.
Pros: Reams of data have shown that people who eat the Med diet live longer, healthier lives. One large study found that women who ate this way had a 46 per cent higher chance of ageing without major chronic diseases or significant impairments in brain health. The wealth of high-fibre foods supports gut health and can keep you feeling satisfied, which is important when trying to lose weight.
Cons: There aren’t any, Jaclyn says – just go heavy on the vegies and light on the prosciutto! “It’s a lifestyle, not a diet,” she says.
Whole30
A month-long elimination diet.
What it is: For 30 days you cut out added sugars, grains, dairy, alcohol, baked goods and legumes from your diet; then you add them back one group at a time, as a way to ‘reset’ your health.
What happens in the body: Elimination diets are used by doctors to diagnose food intolerances because they help identify what may be causing discomfort or allergy-like symptoms as you pay attention to how you feel when you add back a food.
Pros: Proponents find that they lose weight, have more energy and/or improved mood, or simply enjoy being conscious of what they’re eating.
Cons: There are no independent studies on Whole30 and how it affects long-term health and weight loss, but it’s highly restrictive, which is never a good thing, says nutritionist Kristine Clark.