Popular diets review

The Ministry of Health recommends a nutritionally balanced eating pattern consistent with the Eating and Activity Guidelines for New Zealand Adults for good health.

For people wanting to lose weight, the Ministry recommends reducing total energy (calorie) intake by reducing intake of foods and drinks that are energy dense and nutrient poor, for example, sugar-sweetened drinks, alcohol, confectionery and fast food.

For any dietary change to be effective it needs to be sustainable long-term, which usually means making small changes that fit your lifestyle. Physical activity is an important component of any weight loss plan and can help you achieve your weight loss goal and improve your health too.

To help make sense of some of the different dietary approaches out there, the Ministry has reviewed eight popular diets.


Very low calorie diets

A very low calorie diet (VLCD) is a medically supervised diet in which you eat 800 calories or less a day for a short time (usually 6–12 weeks). It usually involves replacing most of your meals with low-calorie, specially formulated shakes, soups or bars. Health professionals sometimes recommend VLCDs to promote rapid weight loss among adults who are obese (that is, those with a body mass index (BMI) over 30 kg/m2) in special circumstances; for example, in preparation for surgery. Most people who need to lose weight should not use a VLCD.

Pros

VLCDs can be effective for weight loss over short periods, under the supervision of a health practitioner.

Cons

VLCDs are hard to follow. They can leave you feeling hungry and low on energy; other side effects can include hair thinning, tiredness, dizziness, cold intolerance, headache, constipation and diarrhoea. Most people tend to put weight they have lost on a VLCD back on soon after coming off the diet as they return to their previous way of eating. VLCDs are not suitable for pregnant or breastfeeding women, children (aged under 16), older people (aged over 65) and those with serious medical and psychological conditions.

Advice

Not recommended without professional advice.

Mediterranean diet

The Mediterranean diet emphasises eating plenty of plant-based foods, such as vegetables and fruits, whole grains, legumes (like lentils, split peas, chickpeas and cooked dried beans, eg, kidney beans and baked beans) and nuts; replacing butter with monounsaturated fats, mainly from olive oil; and eating a moderate amount of fish, poultry and dairy products, with little or no red meat.

Pros

A Mediterranean diet is effective for weight loss when a person follows it for 12 or more months. The diet is consistent with the Ministry of Health’s Eating and Activity Guidelines for New Zealand Adults. Research has shown that the traditional Mediterranean diet reduces the risk of heart disease and stroke, and improves glycaemic (blood sugar) control in people with type 2 diabetes.

Cons

None

Advice

Recommended.

Dietary Approach to Stop Hypertension diet

The Dietary Approach to Stop Hypertension (DASH) diet was developed to help treat and prevent high blood pressure (hypertension). The DASH diet emphasises plenty of vegetables, fruits and low-fat dairy products, and moderate amounts of whole grains, fish, poultry and nuts. It provides a person with a healthy eating pattern that is consistent with the Ministry of Health’s Eating and Activity Guidelines for New Zealand Adults.

Pros

The DASH diet is an effective way to lose weight and become healthier at the same time. Studies have shown that the DASH diet lowers blood pressure, improves glycaemic (blood sugar) control and lowers the risk of heart disease and cancer.

Cons

None

Advice

Recommended.

Very low-carbohydrate diets

Some people see very low-carbohydrate (very low-carb) diets as a better way of losing weight than diets that contain more balanced amounts of carbohydrate and fat. However, research shows that it is not the proportion of macronutrients (carbohydrate, fat and proteins) in a diet that affects weight loss but the total energy (calories).

Pros

Cutting poor-quality carbohydrates (sugar-rich foods and drinks, and food made from refined grains, like white bread, cakes, muffins, and biscuits) from your diet is good for your health.

Cons

Whole-grain and high-fibre grain foods, such as heavy-grain bread and legumes, contain important nutrients, and are good for your health. People can lose weight on very low-carb diets, but they can also do so on other energy-restricted eating plans. Importantly, there is no evidence of the long-term effects or safety of very low-carb diets. The Ministry recommends diets that contain moderate amounts of carbohydrate.

Advice

Not recommended.

Paleo diet

The Paleo diet is an eating pattern claimed to be based on the diet of our ‘hunter-gatherer’ ancestors from the Palaeolithic period (around 2.5 million to 10,000 years BC). It consists of vegetables, some fruit, nuts and seeds, naturally occurring fats and oils, meat, eggs and seafood. While different variations of the Paleo diet exist, the diet usually excludes dairy products, grains, legumes and processed foods, including processed oils, sugar and salt.

Pros

A Paleo diet includes many healthy foods, such as whole and less processed foods, vegetables, fruits, meat, eggs, nuts and seeds.

Cons

The key concern with the Paleo diet is that it excludes entire food groups that are important to healthy eating patterns, including grains, legumes and dairy products.

Also, the diet may encourage eating large amounts of meat, which can be expensive, and runs counter to the Ministry of Health’s recommendation to eat no more than 500 g cooked red meat each week.  

Advice

Not recommended.

Intermittent fasting diets, including the 5-2 diet

Intermittent fasting is a pattern of eating that involves periods of fasting (restricting your energy intake) and non-fasting. The most common example is the 5-2 diet, in which a person eats normally for five days, and then takes in much less energy (usually 500–600 calories per day, which is 25% of recommended requirements) on the remaining two days of the week. Over time, the diet reduces a person’s total energy intake, which leads to weight loss.

Pros

Intermittent fasting diets can be as effective as other energy-restricted diets, and some people may find them easier to stick to.

Cons

Possible side effects from ‘fasting days’ include hunger, low energy levels, light-headedness and poor mental functioning. You still need to make healthy food choices on ‘non-fasting’ days. There has been little research about the long-term effect of intermittent fasting on a person’s weight or health.

Advice

The 5-2 diet may be suitable for some people. Talk to your GP to develop a weight management plan that is best for you. The Ministry does not recommend the 5-2 diet for people with insulin-dependent diabetes.

Commercial weight loss programmes

Commercial weight loss programmes, such as Weight Watchers and Jenny Craig, provide people with eating plans, pre-packaged meals, guidance and support. Programmes typically offer a 1000–1500 calorie-per-day portion-controlled diet plan that produces weight-loss of about 0.5–1 kg per week.  

Pros

Research has found that on average commercial weight loss programmes result in greater weight loss than self-directed programmes do. Many provide counselling, peer support and monitoring.

Cons

Many commercial weight loss programmes exist, and some are better than others. These programmes cost money. To ensure they are effective in the long term, people need to continue to make healthy lifestyle choices after they leave the programme.

Advice

A commercial weight loss programme may provide a more intensive intervention for a person who wishes to achieve more rapid weight loss. It may also provide a more motivating and sustainable option.

Detox diets

Detox diets claim to rid your body of ‘toxins’ resulting from poor diet and lifestyle, improve your energy levels and result in rapid weight loss. They often involve expensive supplements, and require you to cut out whole food groups, typically dairy foods. Some eliminate food all together and allow juice only. The concept of detox diets is unscientific. The body has its own built-in mechanisms to remove waste and toxins. Organs such as the skin, gut, liver and kidney continually ‘detoxify’ the body.

Pros

Cutting out or having a break from alcohol, caffeine or junk food and eating more fruits and vegetables and fewer processed foods is good for your health.

Cons

Detox diets can be expensive. There is no evidence that they actually remove toxins, and they can be harmful. You may lose weight quickly on a detox diet, but this is likely to be because you are losing water and your carbohydrate store, rather than stored fat. You are likely to regain the weight as soon as you start eating normally again.

Advice

Not recommended.

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