Dieting not only can make you fat it can also kill you, or make you ill
The slimming industry is worth well over lb1 billion in the UK alone, yet there is no evidence that diets, drugs, products andorganizations specifically designed to help people lose weight work
in the long-term. There is, however, evidence showing they can be detrimental to our health, even life threatening. Nevertheless, around two-thirds of women and 30 per cent of men are trying to lose weight at any one time despite, as a UK television documentary revealed, the fact is that 95 per cent of dieters fail to lose weight long-term.
Weight is a balance between energy intake (kcalories) and energy expenditure (activity), and if you cut intake below expenditure, or increase expenditure above intake, you will initially lose weight. Diets focus on reducing energy intake, but the initial weight lost is not fat, but a mixture of glycogen (a form of glucose stored in the muscles and liver, which is the most immediately available energy needed by the body and the brain) and water. As soon as the dieter stops dieting, the glycogen and water are replaced. Lack of glycogen causes low blood-sugar levels, resulting in tiredness, irritability, depression and sometimes dizziness and fainting-symptoms many dieters will be familiar with. After the body has reduced its reserves of glycogen and water, it tends to lose the tissue it needs least which, in the body of a sedentary dieter, is lean tissue such as muscle. (You Don't Have To Diet, by Dr Tom Sanders & Peter Bazalgette, Bantam, 1994).
Logically, low glycogen levels result in reduced energy expenditure, which the body achieves by slowing its metabolic rate, ie, the rate at which our bodies use energy. The human body is responding to its own built-in survival instinct.
A recent study looking at the physiological effects of reducing a group of people's weight by 10-20 per cent, and the effects of increasing another group's weight by 10 per cent, found that energy expenditure automatically increased with weight gain and decreased with weight loss in an apparent effort to return the subject to his or her initial weight. The study concluded that: "Maintenance of a reduced or elevated body weight is associated with compensatory changes in energy expenditure, which oppose the maintenance of a body weight that is different from the usual weight. These compensatory changes may account for the poor long-term efficacy of treatments for obesity" (N Eng J Med, 1995; 332:621-8).
Other studies of weight loss have revealed that even after four years the body will still be trying to return to its initial weight (BMJ, March 18, 1995; 310:750).
"Almost anyone can temporarily lose weight," says Professor David Garner from Michigan State University. "It's like holding your breath anybody can hold their breath for 20 seconds, but the implications of holding your breath for two weeks are very different. The same applies to dieting. The dieting industry has capitalized on that ephemeral weight loss, but in fact almost everyone gains the weight back."
The common response to metabolic compensatory change among dieters is to stop and start diets, causing their weight to continually fluctuate, or yo-yo. Both the psychological effects (anxiety, depression, compulsive eating, anorexia and bulimia) and the physical effects are potentially life-threatening. The health risks are particularly high in those who lose a lot of weight suddenly, which is particularly common with "crash diets" and fasts, or in those who are very overweight.
In 1993 the British government's Health of the Nation programme defined being excessively overweight as a body mass index of 30-plus (weight in kilograms divided by height in metres, squared).
Ironically, a perfect example of this was the premature death of Richard Weston, co-founder of the slimming organization Weight Watchers UK. Richard crash dieted several times a year and was warned by his brother-in-law, a cardiologist, that he was unlikely to reach the age of 30 if he continued yo-yo dieting. He did continue, and eventually died from a heart attack, aged 44.
In 1992 the British Heart Foundation was sufficiently concerned about dieting increasing the risk of heart disease to produce and distribute a booklet alerting GPs to the danger.
In addition to coronary disease and heart attacks, there are a number of other health problems associated with yo-yo dieting. These include the previously mentioned decrease in lean tissue (including heart muscle); loss of bone minerals; gout or gallstones; hair loss; fibrosis and tissue scarring; high blood pressure when returning to a normal diet; depression; harmful side effects of appetite-depressant drugs; and shortened lifespan.
Reduced metabolic rate also means that when you start eating normally again you put on weight more easily as your body needs fewer calories.
Women are more at risk from dieting than men because they naturally have, and need, more body fat. Despite an average, healthy woman having up to 30 per cent body fat compared to up to 20 per cent in an average, healthy man, women still live four to five years longer than men, so the extra body fat certainly isn't doing them any harm.
Women need a certain level of body fat for reproductive purposes, as it is involved in the production of the sex hormone estrogen. Between 15-18 per cent is needed for fertility and development of secondary sexual characteristics such as development of breasts and suppression of hair growth on limbs and face. If a woman has less than 15 per cent body fat, she is likely to stop menstruating. The body's own estrogen also helps prevent loss of calcium from bones, reducing the risk of osteoporosis (brittle bones).
Of course, being grossly overweight is also bad for your health, increasing your risk of disease and premature death. The risk of medical disorders such as diabetes, high blood pressure, gout and heart disease increases with increasing body weight, but the health risks of being underweight are often greater than being hugely obese (Sanders & Bazalgette).
There have been remarkably few scientific studies made of slimming techniques. We do, however, know something about the effects of specific types of diets, such as low-fat and low-carbohydrate.
From a health point of view, most people in the western world would benefit from reducing their fat intake, but very low levels can be harmful. We need fat for the provision of essential fatty acids and the provision and absorption of fat-soluble vitamins. A letter in The Lancet in 1990 reported that vitamin A levels in many young women were inadequate because they were switching to low-fat dairy products and avoiding foods such as liver, and another study published in the New England Journal of Medicine in 1993 found that women with low intakes of vitamin A were at increased risk of breast cancer (Sanders & Bazalgette).
Research has also suggested that a low-fat diet may increase aggressive and suicidal tendencies. Following a study of 25,000 Americans, Dr Hyman Engelberg said people who switched to a low-fat diet may have an inability to absorb seratonin, a brain chemical which suppresses aggressive impulses.
In his study, Dr Engelberg reported that he'd also found monkeys on a diet low in saturated fat and cholestrol to be significantly more aggressive than animals on a normal diet (The Lancet, January 9, 1993).
Although British experts were sceptical, Michigan State University's Professor David Garner agreed that dieting does disrupt brain chemistry and lower blood sugar levels, which can lead to emotional changes and mood swings.
Carbohydrate is the best source of energy, therefore it stands to reason that low-carbohydrate diets will result in tiredness, weakness and probably depression. Sufficient carbohydrate in our diet is also essential for brain function.
Meal replacements which are usually in the form of milkshakes, biscuits, snack bars and even chocolate are potentially extremely dangerous. Apart from doing nothing to encourage healthier, long-term eating habits, they may not provide all the nutrients we require and could therefore lead to malnutrition and excessive weight loss, the dangers of which have already been noted.
In May 1992 Food magazine analyzed 14 popular calorie-counted ready meals promoted as slimming aids. They found they were all lacking in salt, eight in fibre and three in fat.
Bulking agents, which are usually in tablet form, are designed to take before meals to fill you up and reduce your appetite. These may cause wind or constipation.
Sea kelp, in the form of tablets, creams, gels and slow-release patches, has long been promoted as a simple, "painless" way to lose weight. Sea kelp contains iodine, which stimulates the thyroid and, it has been claimed, speeds up metabolic rate. While this has not been proven, Dr John Stevenson, consultant endocrinologist at London's Wynn Institute for Metabolic Research, warns that as our thyroid gland produces and regulates the amount of thyroxin we need, stimulating it to produce more could result in increased heartbeat or angina (The European, May 20, 1994).
Sick (often literally) of unsuccessful slimming techniques, an increasing number of people are turning to surgery. If all else fails, cut it off or suck it out. Liposuction is perhaps the most common. It literally sucks out fat from under the skin, but there have been a number of cases of post-operative pain, infection and disfigurement. The fat sometimes grows back in lumps and middle-aged and older people may be left with flabby, sagging skin.
There is the additional risk of blood clots, permanent numbness in the area, severe bruising, loss of blood and lowered immunity to infection, and it can't be used to suck out fat from inside the belly without the risk of damaging internal organs.
Other operations include banded gastroplasty, which aims to make the stomach smaller; ileal bypass, or circumvention of the small intestine, which can cause malabsorption of nutrients and gastrointestinal discomfort; jaw wiring, which prevents eating; the insertion of an inflatable balloon in the stomach to limit the amount of food that can be eaten; and removal of sections of the small intestine to prevent food being digested properly.
As with the majority of other slimming techniques, what the long-term effects of this type of mutilation are is anybody's guess. . .