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Are Fad Diets Worth Their Weight?

Fad diet

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

By Tim Crowe

Fad diets continue to attract public attention with their promises of quick and easy weight loss, but the truth is that these diets are just a large serving size of smoke and mirrors.

How many times have you read and heard that diets don’t work? 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”, examine the downsides to jumping on the latest bandwagon and finally ask: if fad diets don’t 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);
  • focuses on short-term changes to eating and exercise habits;
  • has rigid rules that need to be followed;
  • encourages miracle pills, potions and supplements; and
  • 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 weight loss is mostly from water and carbohydrate stores, not body fat, so the weight 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, headaches, dehydration, constipation, and inadequate vitamin and mineral intake.

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

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. However, weight loss through 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 per day.

Apart from the false belief that a detox diet detoxifies the body, these diets have many well-described downsides including:

  • feelings of tiredness and lack of energy;
  • the expense of buying organic food;
  • the cost of the detox kit if a commercial program is followed;
  • purchasing of supplements if recommended by the diet;
  • difficulties eating out and socialising, as most restaurants and social occasions do not involve detox-friendly meals; and
  • stomach and bowel upsets.

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 by following a detox diet, but this has little to do with the elimination of toxins from the body. Any person who eats more fruit 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.

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. This theory simply doesn’t work.

Popular Diets under the Scientific Microscope

No matter what the fad diet or the pseudoscientific claims behind it, they all achieve weight loss by restricting energy intake through 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 and controlled trials showing that no single 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 focused 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, such as:

  • eating a low-fat, high-carbohydrate diet that is high in fibre;
  • being physically active for at least 60 minutes per day;
  • eating breakfast every day;
  • frequent weighing to monitor weight changes;
  • decreasing food portion sizes; and
  • 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 sensible food and physical activity changes;
  • becoming (and staying) more active while moderately reducing total energy intake by around 2500 kJ (600 calories) – which is equivalent to cutting out one large hamburger, two sandwiches or 1.5 litres of soft drink from your diet, or running for about 40 minutes; and
  • 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 at 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 single diet that works for everyone.
  • Gradual and sensible lifestyle changes are the only realistic way to achieve long-term weight loss success.

Associate Professor Tim Crowe is a nutrition scientist and Accredited Practising Dietitian in the School of Exercise and Nutrition Sciences at Deakin University.