in weight which seem uncontrollable and inexplicable can be one of the most upsetting symptoms of an undiagnosed underactive thyroid. Many of us place a great deal of importance on our physical appearance; and even if your weight is not of great concern, you probably find it distressing to not be able to explain weight fluctuations.
There is a common stereotype that all those suffering from underactive thyroid are overweight — this is simply not true. If you are under the age of 40 you may in fact be underweight. Sometimes the metabolism is so sluggish that your use of dietary protein and other foods is inefficient and consequently you lose weight.
However, there is a tendency for the majority of middle-aged and elderly patients of both sexes with low grade hypothyroidism to put on unwanted weight. The thyroid does not directly cause obesity, but rather leads to symptoms such as tiredness, lack of energy and sugar cravings which in turn can lead you to become overweight.
Here are some further reasons why weight increase and thyroid are connected:
1 The metabolic sluggishness that results from hypothyroidism can cause digestive inefficiency and constipation.
2 The typical muscle and joint pain and stiffness tends to discourage the regular exercise that many patients rely on to control their weight.
3 The characteristic fatigue does not encourage activity. It is so easy ‘not to bother’ and all types of exercise and activity are usually reduced to a minimum.
4 If food is not converted to energy it is often converted into fat reserves. The poor gut absorption and candidiasis so common in hypothyroid, contributes to this conversion process.
5 Intestinal wind can increase the body size, and although the weight may not change — the appearance certainly can.
6 The efficient digestion of food requires the correct stomach acidity, pancreatic enzyme balance, gut absorption and bowel and bladder efficiency. These important areas of our metabolism can all be adversely affected by a depressed thyroid. The inevitable slowing of our metabolic rate leads to fluid retention, weight increase and a general reduction in our metabolic efficiency.
7 Depression is a common symptom of mild hypothyroidism, and depressed people usually have low self-confidence and suffer from anxiety. Unfortunately when these symptoms are experienced many of us turn to food for comfort, particular chocolate and sugar-rich foods. Alcohol is also taken for relief from anxiety. So a vicious circle can be established, involving the pattern opposite.
8 A decrease in brown fat. Brown fat consists of very specialized fat-burning tissue that is located around the neck, shoulders and upper spine, and around the vital organs including the kidney and heart. When the thyroid is underactive, the heat producing properties of this tissue tend to be reduced.
The Thyroid-Brain Link
We know that an underactive thyroid can contribute to weight increase, depression and anxiety. The depression and mood changes are in part caused by the resulting low levels of the neurotransmitters in the brain. These include serotonin, GABA and noradrenaline. However, you may not realize that these neurotransmitters are also involved in appetite and taste regulation. For example, a decreased level of serotonin in the brain can cause a craving for sugar and carbohydrates. This craving can lead to a pattern of eating that is so frequently — and mistakenly — attributed to low blood sugar.
Figure 2: Hypothyroidism, weight gain and depression
How Many Calories Should I Consume?
Overweight patients frequently ask me for a calorie-controlled diet or a ‘special foods’ diet. Many are convinced that weight-loss would occur if they could only find and follow their ‘ideal diet’. They believe that such a diet exists, and that the appropriate 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
