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volume, variety and combining of foods will solve their weight problem. This view has contributed to a vast array of diet books by celebrity authors, each of whom offers their own unique programme for weight loss. Unfortunately, effective and lasting weight loss depends on three elements. These being:

      1 An efficient and healthy metabolism.

      2 Regular activity and/or exercise.

      3 A nutritionally balanced diet that is appropriate to our age, our lifestyle and our health history.

      I find that many patients with mild hypothyroidism have great difficulty losing weight and perhaps more significantly, maintaining any new found slimness. Their metabolism can be so inefficient that I have known patients to increase weight even when following a low calorie diet plan consisting of no more than 800 calories daily.

      Very low calorie diets tend to depress the metabolism and if the thyroid is already underactive, any weight loss on such a diet can only be very temporary. The weight loss-weight gain pattern so common to ‘crash’ dieting often tends to lower self-esteem, self-confidence and general vitality. The consequent frustration can lead to comfort eating and further depression, guilt and despair.

       What Happens When you Diet?

      Your body initially interprets dieting as a potential threat to its fuel supply. A need for emergency energy is therefore quickly recognized by the body. This energy is not obtained from fat, as the body is not able to rapidly utilize fat as energy. This role falls to a substance that is rarely discussed in diet books: Glycogen or animal starch. This is the chief carbohydrate reserve in humans, being stored primarily in liver and muscle tissue. Glycogen exists chiefly in solution with water, and our total reserves only amount to approximately 7-8lb. Although its energy value is less than half that of fat, glycogen converts to energy much more rapidly than fat. As a very small amount of energy is required to release water from the body’s cells, dieting and the response to dieting leads to water loss and glycogen loss that is in solution in the water. This phenomena is well known to sportsmen, marathon runners can lose 10 or more pounds in one race. However, athletes prepare for such occurrences by following a very special pre-race diet for six or seven days. This involves a ‘carbohydrate bleeding’ phase for three days, which depletes the stores of glycogen by eating mainly protein-rich foods. This is then followed by three days of high carbohydrate eating, which serves to provide maximum starch reserves to be utilized during the race.

      The rapid glycogen draining that occurs with many diets (particularly the low starch diets), coupled with the water loss, has two effects that can be very disturbing to the dieter:

      1 A loss of glycogen can lower the body’s blood sugar levels. This hypoglycaemia can cause fatigue, mood changes, dizziness and even faintness. Glucose is the main fuel for the nervous system. The brain, unlike our muscles, does not have a glucose reserve, so it is not surprising that many dieters experience depression, fatigue and mood changes.

      2 Low levels of glycogen can trigger hunger pangs. Carbohydrate foods supply the glycogen stores and raise the blood sugar, providing us with a feeling of fullness and contentment. A high protein, low carbohydrate diet can cause a dieter to become ravenously hungry. Strict diets often lead to food craving.

      Geoffrey Cannon has written:

      

       In our minds we know the difference between going on a diet and being subjected to famine or starvation. But our bodies do not know the difference. When we go on a diet regime we activate the mechanisms in the body that protect us and preserves us in times of famine. And what does the body need to keep it going between times of famine? — Fat. The more often people diet, the more their bodies will protect the stores of fat. ¹

      When discussing water loss in the context of dieting, it is worth noting that over 50 per cent of our weight consists of water.

      Body fat contains very little water. For this reason women’s bodies contain less water than men’s. This is because the average woman has more body fat than the average man. Consequently an overweight person will hold less water than a lean person of similar weight. The proportion of water, fat and fat-free tissue lost with dieting varies from person to person according to their sex and the diet they followed.

       Exercise and Dieting

      Dieting can trigger your innate self-protection responses. Your body will adjust to deal with lifestyle changes, and what we do not use or need will take second place to the essential. An example being a sedentary, non-active person who does not use his/her muscles will tend to lose lean tissue (particularly muscle) when on a diet. This occurs simply because the dieter’s body-wisdom does not recognize muscle tissue as being essential. Conversely an overweight individual’s body will tend to preserve the fat it has become used to. If, however, the dieter is an active, sporting individual who makes use of his/her muscles, the muscle tissue will be seen by the metabolism as essential, and the lean muscle tissue loss will be minimal, but with more fat loss occurring.

       The Thyroid and Weight Loss

      I hope now it is becoming clear that the typical low carbohydrate, calorie-controlled diet is not ideal for you to lose weight.

      Glycogen loss, temporary water loss and possible unwanted loss of lean muscle tissue can occur. The blood sugar can be reduced causing the many symptoms of hypoglycaemia that dieters can experience.

      Essentially dieting slows the metabolism and mentally and physically we become more lethargic. This is our body’s response to a reduced fuel supply.

      To summarize, our metabolism can respond in six ways to a low calorie or low carbohydrate diet.

      1 Glycogen loss occurs from muscle and liver tissue.

      2 Water loss occurs.

      3 Lean tissue (muscle) loss occurs.

      4 Brown fat activity increases with complex carbohydrate food and decreases with high fat or protein foods

      5 The metabolism slows in response to the reduced fuel obtained from food.

      6 Our metabolic rate, largely controlled by the thyroid, slows down through long-term dieting.

      Many chronic dieters learn to recognize that their metabolism has adjusted to their dieting. Initial weight loss is usually followed by a period of static weight, even when the same reduced calorie or carbohydrate diet is being followed. Unfortunately the return to a ‘normal’ diet for non-active dieters, often leads to a rapid return to their original weight or even to a heavier weight. Although the dieting may have ended, their new reduced metabolic rate or tempo is still operating and using calories at a slower rate. The reduction in lean body mass as a result of the dieting causes a fall in the calories used for energy and a vicious circle is established.

      You may be thinking: ‘well yes, very interesting, but what about the thyroid?’. As discussed in other sections of this book, the thyroid is our metabolic clock. Therefore a metabolic slowing as a result of dieting can influence the thyroid. Conversely an existing under-active thyroid will lower metabolic activity, making dieting unsuccessful.

       Brown Fat and the Thyroid

      Research has been done over the last 20 years

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