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What's the fuss about Fad Diets?


‘Diets don’t work’ – how many times have you read and heard that? Yet this one simple statement has stood the test of time. At any time, a large proportion of the population is on some form of diet, yet waistlines are still expanding. With new fad diets emerging all the time, it is time to tackle just what makes a diet a ‘fad’, and what are the downsides to jumping on the latest bandwagon. And most importantly: if fad diets do not work, what does?

How to spot a fad diet

The definition of a fad diet is very subjective. Perhaps the simplest definition of a fad diet is a weight loss diet that becomes very popular quickly, and then falls out of favour just as quickly. Looking at the scope of a whole range of fad diets including such classics as The Atkins’ Diet, The Cabbage Soup Diet, and The Eat Right for your Blood Type Diet, key themes appear that make them a fad rather than a sensible weight loss program. A checklist for a fad diet includes:

  • Promises quick, dramatic or miraculous results
  • Bans or severely restricts specific foods or food groups (carbohydrates are the usual favourite)
  • Focusses on short-term changes to eating and exercise habits
  • Has rigid rules that need to be followed
  • Encourages ‘miracle’ pills, potions and supplements
  • Makes claims based on a single study or individual testimonials

Why fad diets are a problem

Fad diets are popular because they offer the promise of quick and easy weight loss. The truth is that the rapid weight loss is mostly from water and carbohydrate stores, not body fat. This weight loss quickly returns once a person starts to eat and drink normally again.

By cutting out key foods, fad diets can cause a range of problems including:

  • Weakness and fatigue
  • Nausea and headaches
  • Dehydration
  • Constipation
  • Inadequate vitamin and mineral intake.

Fad diets often encourage a short-term change in eating behaviour, rather than encouraging healthy changes that can be sustained in the long-term.

Detox diets: a case study

Detox diets are high on the list of dieting fads. Detox diets make amazing promises, including dramatic weight loss and more energy – all achieved by ‘flushing’ toxins from the body. Weight loss seen on such diets though is entirely due to their restrictive nature, and has little to do with the ‘elimination of toxins’. The idea that we need to follow a special diet to help our body eliminate toxins is not supported by medical science. Our lungs, kidneys, liver, gastrointestinal tract, and immune system remove or neutralise toxic substances within hours after we eat them and work 24 hours a day.

Apart from the false belief that a detox diet is actually ‘detoxifying’ the body, these diets have many well-described downsides including:

  • Feelings of tiredness and lack of energy
  • Expense of buying organic food
  • Cost of the detox kit if a commercial program is followed
  • Purchasing of supplements if recommended by the diet
  • Stomach and bowel upsets
  • Difficulties eating out and socialising as most restaurants and social occasions do not involve ‘detox-friendly’ meals.

Very restrictive detox diets such as water or juice only fasting are not the safest way to lose weight and should not be used for more than a few days. These diets, if done improperly or for too long, may result in nutrient deficiencies.

Many people do feel better for following a detox diet, yet this has little to do with the elimination of toxins from the body. Any person, especially someone who has a poor food habits and lifestyle to start with, who eats more fruits and vegetables, drinks more water and eats less foods high in fat, salt or added sugar, and drinks less alcohol and caffeine will usually feel better feel better.

The detox fad encourages the idea that a person can lead an unhealthy lifestyle for most of the year and then undo the damage in a few days with a rapid detox.  A theory that simply does not work.

Popular diets put under the scientific microscope

No matter what the fad diet or the pseudo-scientific claims behind it, they all achieve weight loss by restricting energy (kilojoule) intake. This is done by either changes in portion size, eating frequency or reductions in either the amount of fat or carbohydrates eaten. Despite the common factor of restricting energy, an amazing diversity of diets exists.

The scientific jury is now firmly in, with dozens of high-quality, randomised controlled trials showing that no one dieting option is the magic solution for everyone. Apart from some short-term success for particular diets – mostly low-carbohydrate diets – all of the popular fad dieting approaches fare poorly for weight loss and sustainability after the ‘honeymoon period’ of the first few months is over.

If diets don’t work, then what does?

The weight loss literature is a minefield for diets that result in poor adherence and weight rebound. The path to successful weight management includes lifestyle changes together with a focussed and realistic strategy. Observing the nutrition and lifestyle habits of people who are successful at taking weight off, and importantly keeping it off, can provide some important clues to ‘what works’.

Long-term successful ‘weight losers’ make a conscious effort to adopt a range of weight-loss strategies from the list following.

  • Eating a low-fat, high-carbohydrate diet which is high in fibre
  • Being physically active for at least 60 minutes per day
  • Eating breakfast everyday
  • Frequent weighing to monitor weight changes
  • Decreasing food portion sizes
  • Eating less sweets and take-away food.

Adding to the habits of successful weight losers, a comprehensive review of the scientific evidence has found common themes and strategies that predict the ability of someone to maintain their weight loss. These include :

  • Having regular and ongoing support, through a community based weight loss group, a dietitian or GP, on the internet, or through friends
  • Using behaviour change techniques including goal setting, self-monitoring of weight, relapse prevention and of course sensible food and physical activity changes
  • Becoming (and staying) more active in addition with moderately reducing total energy intake by around 2500 kJ (600 Calories) less than your usual total energy needs per day. That’s equivalent to cutting out one large hamburger, two sandwiches, or 1.5 litres of soft drink from your diet, or alternatively running for about 40 minutes
  • Eating less fat (which is high in kilojoules) and more protein (which may help reduce appetite and preserve muscle mass)

For most people, fad diets are not the way to achieve long-term weight loss. The key to long-term success lies in learning from those people who are successful in losing and keeping weight off. Small and realistic lifestyle changes appear to be the best formula, combined with ongoing support and advice, and perseverance.

Key Points

  • Most people who go on a diet will regain the weight soon after
  • Of the popular fad diets, none of them can be considered superior to the others – weight loss is far from spectacular and they are all hard to stick to
  • The messages given by fad diets can dramatically change people’s perception of which foods are healthy
  • There is no one diet that works for everyone
  • Gradual and sensible lifestyle changes are the only realistic way to achieve long-term weight loss success.


Confused about the mixed soup of nutrition messages being stirred through the media? Tim maintains an active nutrition blog at where you’ll find the latest nutrition research and controversies discussed in straight forward language, distilling out what you need to know for your better health.

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