Dieting Harms: Be Careful

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Obesity is number one enemy of health (Read Obesity Harms: do you know). Losing weight and looking good has been an obsession since ages. Dieting is the most common method adopted for weight loss, other methods being drugs and surgery. Theoretically, the principle of weight reduction is simple. Obesity is caused by storage of excess energy in the body. Weight can be reduced by creating an energy deficit in the body either by reducing intake of food or by increasing the energy expenditure through physical activities. Due to energy deficit the body is forced to utilize body reserves leading to weight loss.

Up to this point, the things are straight. But ask a person who had ever tried losing weight by dieting for a limited period. It is a common experience that after dieting period is over the weight comes back. It often overshoots the previous weight. Repeated attempts to lose weight does not ensure desired weight maintenance over long periods. People often give up efforts to lose weight and in turn expose themselves to obesity hazards. I call this phenomenon as ‘back to square one’. During the Post Graduate Certificate Course in Nutrition from National Institute of Nutrition (NIN), India, I got new insight into weight management pitfalls. In this post I will share the knowledge with you to make you aware about actual events which occur during dieting to help you to plan a strategy for weight loss in future.

 The Body Composition

Before studying dieting, we must know about the body composition and few scientific terms. Our body has two important components. Lean body mass or LBM (consisting of water, proteins,  glycogen and  minerals) and Fat. In normal state the LBM and Fat are maintained at 80% & 20% for males and 75% & 25%  for females respectively. In an obese, this ratio is altered.

Our energy expenditure is related to Basal Metabolic Rate (BMR) and Thermic Effect of Food (TEF). BMR is the energy required to maintain vital & basic body functions like breathing, heart beat, repair of tissues etc during rest/sleep. BMR constitutes 80-85% of the total energy expenditure.  BMR is directly proportional to LBM. More the LBM,  more the BMR and energy utilization. When LBM decreases, BMR also decreases. When we eat food we feel warm. This effect is called TEF, which represents the energy expended for mechanical digestion of food. BMR, TEF and daily activities like walking, doing house hold works etc comprise our total daily energy expenditure.

What Happens When We Diet?

To understand dieting dangers, we will examine two hypothetical case studies as under:-

Hypothetical Case Study No 1

To understand the body responses to dieting, lets us take a hypothetical example of a 80 kg individual, who has been subjected to dieting to reduce weight. Before dieting, his body weight is 80 kg, (50 kg LBM and 30 kg fat). His calorie expenditure is the sum of BMR (1250 Kcal), TEF (150 Kcal) and daily activity (500 Kcal) totalling to 1900 Kcal. His Kcal intake and expenditure are balanced.  There is no weight gain or loss. For dieting, he is now subjected to 1000 Kcal diet for two months (period 2 & 3). After two months (period 4), normal diet is resumed.

Dieting Dynamics

Period 1234
Weight (kg)80747272
LBM (Kg)504746.546.5
Fat (kg)302725.525.5
BMR (cal)1250104710231163
TEF (cal)15010095150
Daily activity (cal)500400380450
Daily expenditure (cal)1900154714981763

It can be seen that after dieting for one month his weight has reduced by 6 kg (3 kg each reduction in LBM and Fat). Encouraging indeed! He continues to diet for next 30 days with same diet regime. Now there is  a problem. His weight has reduced by  two kg only against the expected loss of 6 kg in spite of complete adherence to the diet schedule. A reason for disappointment.

How this has happened?  Let us look  at rows BMR, TEF, daily activity and total calorie expenditure again. In the column period 1, the calorie intake and expenditure are balancing each other at 1900 Kcal without any weight gain or loss. In the period 2 and 3, BMR, TEF, daily activity expenditure and total calorie expenditure have decreased from period 1 (1900 Kcal) to period 2 (1547 Kcal) and period 3 (1498 Kcal). Since the calorie intake is same (1000 Kcal), it can be seen that the calorie deficit has reduced leading to lesser weight loss.  Further in  the  column period 4, when normal diet  is resumed (1900 Kcal), the person is spending only 1763 Kcal against intake of 1900 Kcal. He is taking an excess of 137 Kcal per day which will cause immediate weight gain to earlier level or may exceed the original value. The lessons learnt are:-

dieting Photo by klf_bdf
After dieting weight comes back once normal diet resumed Photo by klf_bdf
  • The longer you diet, the lesser is the weight loss
  • When you resume normal diet, weight gain occurs
  • Once a nibbler, always a nibbler. You can’t go back to your original diet

The question arises why it happens? Human body has evolved from hunter days, when regular food supply was not available. Human civilization has seen famines and droughts. The body has adapted to fight adverse times by reducing its energy expenditure to maintain essential body functions. Whenever food shortage occurs, the body tries to counter it by reducing BMR and other energy expenditures (as seen in the table). When food is available, calories are stored for bad times. This is termed as Adaptive Thermogenesis (AT). It is seen that  during re-feeding phase, most of the subjects feel extremely hungry and overeat. This genetic code is functional in the human beings even in the twenty-first century. Dieting is perceived as bad times by the body and this code is activated. It is easy to imagine the frustration and anger of a dieter after adhering to a difficult program for four to eight weeks with minimal weight loss and weight gain later.

If AT is kept in mind then most of the crash diet programs are futile. Even weight loss by surgery is also worthless. As soon as the intake is reduced (by whatever means; dieting, drugs and surgery), the AT is activated. BMR and TEF are gradually reduced to preserve energy. The body metabolism becomes more efficient and loss of energy is minimized nullifying all the efforts.

Hypothetical Case study No 2

Let us take another hypothetical example of a woman undergoing repeated dieting. Miss IM Beauty is 23 years old with 52 kg weight. Her LBM is 39 kg (75%) and Fat is 13 kg (25%). After four years, she gains about 9 kg. Her weight is now 61 kg. Due to weight gain her body composition has changed to 34% fat  and 66% LBM. Summers are nearby and she wants to look attractive in her swimming suit. To reduce her weight, she joins a crash diet plan. She is put on a  650 Kcal/per day crash diet regime. She expects to attain her original weight of 52 kg after 10-12 weeks. She adheres to plan and reaches her original weight of 52 kg. So far so good. Now there is a catch. Of the 9 kg she has lost, 4.5 kg were fat, 2.2 kg water and 2.3 kg muscle. Though she has attained her original weight of 52 kg, she is now fatter with the same weight. Her body composition has changed to LBM-35 kg (68%), Fat 16 Kg (31%) from earlier LBM-39 kg (75%) and Fat 13 kg (25%). After attaining successful weight loss, she reverts back to her original diet. Over a period of time, she regains 9 kg and comes back to the pre-dieting weight of 61 kg. But something drastic has happened to her. The 9 kg she regained is not what she has shed, rather she had gained 6.8 kg fat and 2.2 kg water. Now her body fat composition is 38%. If same cycle is repeated for 3 more years with various diets, she might again weigh 52 kg, but her body composition will be altered to 60% LBM and 40% fat.

Miss IM Beauty, our slightly overweight female dieter is now 31 years old. Due to repeated dieting, her fat percentage has increased over time reducing the BMR. Reduced BMR has made her a metabolically reduced body system requiring fewer calories to maintain itself. If she consumes the same amount of calories as earlier, she may gain about 5 kg per year! Now she is no longer simply overweight, she is clinically obese. Her reduced amount of active lean tissue and slowed metabolic rate have plunged her into a vicious cycle of weight gain. She watches herself getting heavier even as she consciously controls her calorie intake. At this point she might say ” I can’t avoid gaining weight. My metabolism is low. I am not as lucky as other people who can eat and not gain weight”. She is correct.

obese female photo
Repeated dieting leads to YO YO syndrome        Photo by Tobyotter

Why this has happened? It has happened because during the initial phase of dieting, the weight loss is primarily due LBM loss (water, glycogen, minerals and proteins). Later, the fats are lost. In this phase, fat cells are only depleted, not destroyed. When normal feeding is resorted to, fats are replenished faster than LBM, altering the LBM:Fat ratio in the favour of fat. Increase in body fat reduces BMR, which in turn reduces the energy expenditure of body. This state is called as Yo-Yo Syndrome. At this stage weight loss becomes extremely difficult. It will lead to increase in weight even with routine normal diet as per age and activity. The lessons learnt are:-

  • Repeated episodes of dieting will progressively increase fat percentage in the body.
  • Increased fat percentage will reduce BMR and make weight loss difficult.

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Weight loss clinics are common Photo by Patrick Feller

Overweight people are aware of the consequences of obesity and want to reduce their weight. Encashing the sentiments of people, the weight loss services & products have become a multi-billion dollar industry nowadays. Internet is full of innumerable products; herbal teas, self styles secret remedies, weight loss recipes, sauna belts, electric walkers, gym equipments etc, each claiming weight loss in record time. Markets are full of dietitians, obesity clinics, crash diets and proprietary preparations claiming successful weight loss from their diet plans. Advertisements like “I lost twenty kg weight in just one month” are highly lucrative. As discussed earlier, people often try them and get disappointed and frustrated later on.

Weight reduction through crash dieting plans works only for initial one to two months. This phenomenon is exploited by crash diet planners, obesity clinics to propagate their  product or services. There are large number of crash diet plans available in the market. There are thousands of videos in YouTube claiming quick weight reduction. Readers can search internet for such videos and write ups. Whether these work or not I don’t know, since I have not tested them. But one thing is sure. The weight is regained quickly. We don’t see advertisements like I am still slim after ten years” or “Our therapy maintains weight even after one year. It is simply not possible.

Further, most of the crash diets are harmful. They do not cater for requirement of vitamins and minerals essential for good health. It is not possible to maintain nutrition with a diet less than 700-800 calories. Repeated dieting increases efficiency of adaptation mechanisms, making weight loss more difficult. It also alters the fat and LBM ratio, reducing BMR and causing weight gain even with small amount of food.


Obesity is harmful and one of the main obstacles for health investment (Read: Health is Investment: Do You Know).  The centenarians all over the world are lean and thin (refer to centenarians secrets). In this post we have learnt the following lessons:-

  • The longer one diets, the lesser is the weight loss.
  • Re-feeding results in weight gain.
  • Repeated dieting leads to yo-yo syndrome making weight loss difficult.

Dieting is harmful and must not be resorted as a quick method for weight reduction. Dieting amounts to penny wise pound foolish approach. You may win a battle in the short-term but will lose the war in the long-term. So never, never, never, never  and never diet to reduce weight.

In reality, weight reduction is a long-term commitment by you to your self. The weight reduction industry is flourishing, because everyone wants quick results. One must know that in health investment, there are no shortcuts. There are no magic remedies. Losing weight requires a total change in life style. Only those people who will change their lifestyle totally will be able to maintain weight and live long and live healthy. Until this truth is kept in mind, weight reduction by dieting alone will be a futile attempt all the times.

Remember: Dieting is harmful; Never diet cares for your health. We aspire to make you a healthy, disease and disability free centenarian. In the next post, how to reduce and maintain weight on  a long-term basis will be discussed. I will also share with you my own story of reducing my weight from 80 kg to 70 kg in 2005 and maintaining it till date. Don’t miss it.

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