What are fad diets?

Fad diets are weight loss diets that promise fast results, often without any scientific basis. These type of diets frequently involve eliminating whole food groups, which starves your body of important nutrients. They can generally provide short-term weight loss results, but are not sustainable in the long-term and can lead to weight gain after the diet is finished.

Identifying fad diets

Fad diets can generally be identified by some of the following features, which can include:

  • Promising quick weight loss results in a short amount of time;
  • Promoting certain foods, or food combinations;
  • Excluding particular food groups (e.g. carbohydrates);
  • Claiming that you do not need to exercise;
  • Basing diets on single testimonials, and;
  • Basing diets on studies that are not scientifically proven.

Examples of fad diets

Some examples of fad diets include:

  • Cabbage soup diet, which involves eating predominantly large amounts of cabbage soup over seven days;
  • Atkins diet, which involves limiting the consumption of carbohydrates and eating high amounts of protein;
  • Blood type diet, which involves eating certain foods based on your blood type;
  • Five and two diet, which involves intermittent fasting. This diet allows consumption of unlimited calories for five consecutive days, followed by a limited calorie intake for the next two days;
  • Grapefruit diet, also known as the Hollywood diet, which claims that grapefruit has a special fat-burning enzyme;
  • Lemon detox diet, also known as 'master cleanse', which involves eating no food and only drinking lemon tea or lemonade made from lemon juice, maple syrup and cayenne pepper;
  • Slim-fast and other liquid diets, and;
  • Specific diet and supplement pill diets.

Health risks of fad diets

Fad diets commonly restrict certain food groups, which means that there can be inadequate vitamin and mineral intake. This can lead to the occurrence of short-term health problems, which can include:

As fad diets vary in many ways and can restrict many foods, the long-term health implications of each fad diet remain unclear.

Fad diets are not sustainable

Although fad diets may give some weight loss results in the short-term, they are generally not sustainable. This means you can not follow them forever and when you stop the diet and return to your old lifestyle habits, your body weight is likely to increase again. Fad diets are not sustainable due to the limitations placed on the food variety and amount, which can cause cravings and hunger. In the long-term, fad diets that restrict the intake of certain food groups can prevent you from getting adequate amounts of nutrients to healthily sustain your body.

Energy balance

In a healthy balanced diet, an important aspect to monitor is the amount of energy you consume, compared to the amount of energy your body uses up. If you consistently take in more energy than your body uses, over time your body will store the excess energy as fat, leading to weight gain. To lose weight, the total amount of energy that your body uses must be more than the amount of energy taken in.

Energy in food

Energy in food is measured in kilojoules or calories (1 calorie = 4.2 kilojoules). Different foods vary in the amount of energy they provide because they contain different amounts of the three macronutrients which are fats, proteins and carbohydrates. Fats are the most energy-rich macronutrient, supplying about 38 kilojoules per gram. Proteins and carbohydrates supply around 17 kilojoules per gram. All three macronutrients contribute to the healthy maintenance of your body -  fats help with nutrient absorption, proteins are important in the building of new cells and carbohydrates provide long lasting energy.


Substances in foods that are necessary for the body to function and grow. They include macronutrients, which provide energy and micronutrients, which are substances needed in small amounts such as vitamins, minerals and trace elements.


1. One of the three macronutrients in foods that supply the body with energy. Food rich in proteins include meats, legumes and dairy foods. 2. Large molecules, such as antibodies and albumin, that are found in the blood.

Healthy eating and exercise

To successfully maintain a healthy weight lifestyle changes, that are sustainable in the long term, will need to be adopted. This can involve eating smaller portion sizes, exercising more or eating healthy alternatives. The most important thing to remember when trying to lose weight is the amount of energy consumed needs to be less than the amount of energy used up. Exercising and being active is a great way to burn any extra kilojoules.

To reduce weight, the amount of energy used up must be more than the amount of energy consumed. 

Eating a balanced diet, including the five major food groups, provides your body with all the required nutrients. A healthy diet includes:

  • Vegetables and legumes (which include beans, peas and tofu);
  • Grain or cereal-based foods, such as breads, rice, breakfast cereals and pasta;
  • Lean meats, fish, poultry and eggs, legumes, nuts and seeds;
  • Fruits, and;
  • Dairy and dairy substitutes (such as non-dairy milks fortified with calcium).

The Australian Dietary Guidelines [1]  also provide advice about required kilojoule intake, the various dietary fats and limitations of processed foods.

1. Australian dietary guidelines 1-5. Australian Government - National Health and Medical Research Council. Accessed 19 June 2015, from

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