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Why Diets Fail and How to Diet Successfully

Updated on November 15, 2016
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Dr John uses his Biochemistry & Physiology research background (PhD) to develop authoritative reviews of dieting, weight loss, obesity, food

People throughout the world spend billions on weight-loss products every year. Governments around the globe spend billions on trying to get people to lose weight because of the staggering cost of the obesity epidemic. TV programs such as 'The Biggest Loser, Excess Baggage, the Weight is Over' are like watching modern gladiators do battle with their bulges, but the advice is misleading - extreme exercise does not work in the long term.

There is so much advice and methods available - low-calorie prepared meals, meal-replacement shakes, supplements, diet books, dieting programs and schemes. But most people are doomed to failure with at least 90% of all people who try to lose weight failing and reverting to their original weight or putting on more weight. Research has shown that dieting makes some people fatter. So what works and what can be done to lose weight and keep it off?

It is hard to lose weight. It takes a long time and too keep it off requires permanent lifestyle changes including regular exercise.


Recent research has identified the cause of the global obesity epidemic as passive over-consumption of modern foods that are too rich in fat and calories. See At Last - Cause of Global Obesity Identified - We Passively Eat Too Many Calories

People everywhere are getting heavier simply by eating normal food and normal meals. But the modern food we eat (since the 1970s) is highly processed and contains many more calories per weight and volume. Modern food processing has increased the calorie density of food so that its much higher than whole foods. This includes white four, bread and biscuits, white rice and packaged foods with added sugars and fats. Now when people eat normal meals, that is not fast foods, but home prepared meals, they passively consume too many calories. The term 'passive' means that people are not deliberately eating high fat and high calorie foods. Additionally both meal frequencies (snacks) and portion sizes increased substantially. Western diets, processed foods and western lifestyles cause obesity in most countries.

So people eat more, they eat more often, and most of what people eat is full of fat and calories for the same volume and weight of the food. Is it any wonder most people get fatter each year and that there is a world wide obesity epidemic?

The persistent increase in weight with age seems to be inevitable for all people including runners and those who exercise regularly.

A research study of some 22,000 men and women over a 5 year period, aged from 20-69 years, showed that their mean annual weight gain was about 400 g in women and 390 g in men.

These weight increases even apply to people who exercise regularly.

A study of 4,769 regular runners, aged from 18 and 50 years, showed that the average male runner gained about 3.3 pounds (1.5 kg ) and increase their waist measurement by 3/4 inch (2cm) every 10 years.

Over a ten year period about 30% of the runners became moderately overweight as they gained weight every year. The study concluded that the only way to stop the inevitable weight gain was to run more and more as they got older. Running distance would have to be increased by 1.4 miles per week. This meant that runners who averaged 10 miles per week as 30 year olds would have to double their weekly distance to about 24 miles by the age of 40 years, just to maintain their original weight.

Clearly exercise helps in a weight loss program but it exercising will not keep the weight off and stop the inevitable gain in weight with age.

As the figures below show, exercising is a very inefficient way to lose weight and must be accompanied by reductions in food and calories eaten.

Calories Burnt for Various Exercises

Most Diets Fail. The Maintenance Phase is the Least Successful

The figure below shows that most diets fail and most people regain some of the weight they have lost.

Many people have unreal expectations of the rate they will lose weight and they become frustrated and give up. People should be realistic and expect to lose no more than 1 lb (0.5 kg) per week.

Successful dieting requires major lifestyle changes and eating habits that develops into the maintenance phase of dieting.

Expected Rate Loss with Various Interventions (kg)
Expected Rate Loss with Various Interventions (kg) | Source
Expected Rate Loss with Various Interventions (lb)
Expected Rate Loss with Various Interventions (lb)

What Calorie Reductions are Required to Lose Weight?

The generally recommended daily calorie intake for men is about 2550 calories per day for men and 1940 calories per day for women. The number of calories needed varies greatly depending on lifestyle, age, weight, your body composition and your basic level of daily activity.

So to lose weight and keep it off people should reduce their calorie intake by a 20 - 25%. This is equivalent to about one meal a day, given that the between-meal snacks and drinks add an extra meal to the three meals most people eat.

This has lead some to suggest not eating lunch or cutting out one of the other daily meals see ( Quickest Way to Lose Weight - Don't Eat Lunch ). Others have suggested reducing portion sizes at every meal by 25% - eating less at every meal ( Desize Me - Diets that Work by Reducing Portion Sizes - Only Eat the Better Half ). The other strategy is to replace what we eat now with whole foods or health foods to generate the same calorie reduction.

Basically what we have to do is eat 25% LESS than we eat now ALL the TIME.

Will-Power and Why Diets Fail

Diets don't work in the long run because:

  • They are meant to be temporary BUT longterm, whole of lifestyle changes are required
  • The weird foods and meals are not designed to be sustained. When people stop the diet they revert to the food and meals they consumed before and put it all back on again.
  • People assume that they can diet without feeling hungry. If you eat 25% less you have to expect you will feel hungry and be prepared for a long battle to cope with the hunger
  • A study of 4129 individual twins in Finland, looked at how the number of weight loss episodes of 5kg affected their final weight. It showed that dieting itself may induce small subsequent weight gain, independent of genetic factors. People who tend to gain weight, diet more frequently, fail and then put on more weight. This creates a positive relationship between dieting and weight gain in the lone term
  • Diets don't deal with willpower and the psychological changes required to change behaviour, habits, eating patterns and lifestyles - permanently.

Metabolic Suppression (Adaptation) in Response to Weight Loss and Dieting

Recent research has suggested that the cause of diet failure may not be willpower, but the body's natural tendency to maintain weight at a predefined 'set point'. This set point weight is determined by genes and life experience. It is related to the starvation response that triggers a decline in metabolic rate. When a person's weight drops below the set point various responses are triggered so that they burn fewer calories, they feel hungry and the brain acts to get the person to eat more food. It is akin to a starvation state of emergency. People who lose weight show a slowing of resting metabolic rate. Studies of participants in the “The Biggest Loser” televised weight loss competition confirmed that the suppression remained 6 years after the weight was lost. The study found that:

  • Mean Resting Metabolic Rate after 6 years was about 500 Cal /day lower than expected.
  • Participants who lost more weight at the end of the competition showed the highest metabolic suppression.
  • People who were the most successful at keeping their weight down after 6 years showed the highest metabolic slowing.

This suggests that the 'set point' persists and may even increase when people put on weight.

Conclusion: The metabolic adaptation or suppression is permanent impediment to weight loss attempts through dieting. This once again stresses the need for long term and permanent life-style changes in eating patterns, activity and exercise.

Does Gastric Lap Band and Other Surgical Interventions Work?

The simple answer is Yes!

But it is very expensive and still requires will power and diet control to be effective in the long term.

It is known that about 5-10% of lap band surgery patients regain weight, largely because the things that caused them to be overweight in the first place remain after surgery.

About 80% of patients an upward creep in weight so that they gain 5-10 pounds.

About 20% of patients continue to increase in weight. The new tiny stomach (about the size of an egg) expands by 10-15% in most patients. Excess eating can stretch the stomach even more.

Eating too much of the wrong foods such as high-sugar and high-fat treats can bring the weight back.

So even surgery patients are required and encouraged to change their eating and exercise habits to maintain their new weight.

Conclusion: How to Lose Weight Successfully and Permanently without Surgery

The answer is simple:

Develop the Willpower to Reduce your Daily Calorie Intake by 20% (300 calories).

Easy to Say! Hard to Do!

Keeping it Off! Reports from people who have succeeded in keeping weight off over a long period of time suggest the following requirements:

=> Exercising regularly and often

=> Putting up with hunger

=> Maintaining constant vigilance

=> Resisting cravings to the best of their ability

=> Keeping a close track of weight - the 'scare graph'

=> Controlling what food is eaten (better diet) and how much (portion size and daily food intake)

=> Making permanent Lifestyle Changes in Eating Patterns ('skip lunch'), Activity and Exercise

© 2012 Dr. John Anderson


Submit a Comment

  • MurciélagoHeart profile image

    MurciélagoHeart 5 years ago from San Francisco

    The title is a little strange, but it's an excellent article.

  • KimmiS profile image

    KimmiS 5 years ago from Vancouver, Canada

    Very long article! Lots of good information.

    An awesome alternative to 'hunger pangs' is filling those gaps in your dinner with fresh vegetables. They are low in calories and in fat. Just keep away from dips dressings and sauces when you do this.

  • BlissfulWriter profile image

    BlissfulWriter 5 years ago

    There is also the theory that is not how much we eat, but it is the type of foods we eat. In particular, excessive sugar is a big part of the obesity epidemic. Just Google "Sugar Obesity" and you will find quite interesting material.

    The body naturally has built in signals and is a fine-tune computer and know exactly how much to eat and when. The problem is that sugar and other environment effects (such as time constraints and mind busy on other things) throws off the body's own balancing mechanism and metabolism.

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